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Dojnov B, Božić N, Nenadović V, Ivanović J, Vujčić Z. Purification and properties of midgut α-amylase isolated from Morimus funereus (Coleoptera: Cerambycidae) larvae. Comp Biochem Physiol B Biochem Mol Biol 2008; 149:153-60. [DOI: 10.1016/j.cbpb.2007.09.009] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2007] [Revised: 09/05/2007] [Accepted: 09/05/2007] [Indexed: 10/22/2022]
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53
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Abstract
The major alpha-amylase in honey was characterized. The optimum pH range and temperature were determined for the enzyme as 4.6 to 5.3 and 55 degrees C, respectively. The enzyme was stable at pH values from 7 to 8. The half-lives of the purified enzyme at different temperatures were determined. The activation energy for heat inactivation of honey amylase was 114.6 kJ/mol. The enzyme exhibited Michaelis-Menten kinetics with soluble starch and gave KM and Vmax values of 0.72 mg/mL and 0.018 units/mL, respectively. The enzyme was inhibited by CuCl (34.3%), MgCl2 (22.4%), and HgCl2 (13.4%), while CaCl2, MnCl2, and ZnSO4 did not have any effect. Starch had a protective effect on thermal stability of honey amylase. Therefore, it might be critical to process or control the amylase in honey before incorporation into starch-containing foods to aid in the preservation of starch functionality. One step could involve heat treating honey with other ingredients, especially those that dilute and acidify the honey environment.
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Affiliation(s)
- Sibel Babacan
- Food Science Research Center, Univ. of Rhode Island, 530 Liberty Lane, West Kingston, RI 02892, USA
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54
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Buckow R, Weiss U, Heinz V, Knorr D. Stability and catalytic activity of alpha-amylase from barley malt at different pressure-temperature conditions. Biotechnol Bioeng 2007; 97:1-11. [PMID: 17013936 DOI: 10.1002/bit.21209] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The impact of high hydrostatic pressure and temperature on the stability and catalytic activity of alpha-amylase from barley malt has been investigated. Inactivation experiments with alpha-amylase in the presence and absence of calcium ions have been carried out under combined pressure-temperature treatments in the range of 0.1-800 MPa and 30-75 degrees C. A stabilizing effect of Ca(2+) ions on the enzyme was found at all pressure-temperature combinations investigated. Kinetic analysis showed deviations of simple first-order reactions which were attributed to the presence of isoenzyme fractions. Polynomial models were used to describe the pressure-temperature dependence of the inactivation rate constants. Derived from that, pressure-temperature isokinetic diagrams were constructed, indicating synergistic and antagonistic effects of pressure and temperature on the inactivation of alpha-amylase. Pressure up to 200 MPa significantly stabilized the enzyme against temperature-induced inactivation. On the other hand, pressure also hampers the catalytic activity of alpha-amylase and a progressive deceleration of the conversion rate was detected at all temperatures investigated. However, for the overall reaction of blocked p-nitrophenyl maltoheptaoside cleavage and simultaneous occurring enzyme inactivation in ACES buffer (0.1 M, pH 5.6, 3.8 mM CaCl(2)), a maximum of substrate cleavage was identified at 152 MPa and 64 degrees C, yielding approximately 25% higher substrate conversion after 30 min, as compared to the maximum at ambient pressure and 59 degrees C.
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Affiliation(s)
- Roman Buckow
- Department of Food Biotechnology and Food Process Engineering, Berlin University of Technology, Koenigin-Luise-Str. 22, D-14195 Berlin, Germany
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55
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Vallee BL, Galdes A. The metallobiochemistry of zinc enzymes. ADVANCES IN ENZYMOLOGY AND RELATED AREAS OF MOLECULAR BIOLOGY 2006; 56:283-430. [PMID: 6364704 DOI: 10.1002/9780470123027.ch5] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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56
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57
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Bautista LF, Martínez M, Aracil J. Adsorption of α-amylase in a fixed bed: Operating efficiency and kinetic modeling. AIChE J 2006. [DOI: 10.1002/aic.690491016] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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58
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Tanaka A, Hoshino E. Secondary calcium-binding parameter of Bacillus amyloliquefaciens alpha-amylase obtained from inhibition kinetics. J Biosci Bioeng 2005; 96:262-7. [PMID: 16233519 DOI: 10.1016/s1389-1723(03)80191-3] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2003] [Accepted: 06/09/2003] [Indexed: 11/21/2022]
Abstract
Calcium is required for the stabilization of alpha-amylase because of primary binding (essential binding), but has been shown to inhibit hydrolytic catalysis due to secondary binding at the catalytic site in the enzyme. The role of calcium in the hydrolysis of soluble amylose by Bacillus amyloliquefaciens alpha-amylase was characterized using the equilibrium dissociation constant (K(m)) and k(cat) for the hydrolytic catalysis. The enzymatic hydrolysis was inhibited by a relatively high concentration of calcium ions ([Ca2+] > or = 2.0 mM). The dissociation constant (Km) was increased with increasing calcium ion concentration. Because k(cat) was practically constant at the high calcium concentration range, a competitive inhibition kinetic model was applied to calculate the inhibition parameters in terms of the secondary calcium binding to the alpha-amylase. The enthalpy and entropy changes for the secondary binding were 54.8 kJ/mol and 215 J/mol.K, respectively, and these values suggest a strong entropic affinity for the bivalent ion binding to the enzyme. The thermodynamical analysis clearly shows the conformational changes in this a-amylase during the primary and secondary calcium ion binding.
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Affiliation(s)
- Atsushi Tanaka
- Wakayama Research Laboratories, Kao Corporation, 1334 Minato, Wakayama-shi, Wakayama 640-8580, Japan.
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59
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Hashim SO, Kaul RH, Andersson M, Mulaa FJ, Mattiasson B. Differential scanning calorimetric studies of a Bacillus halodurans α-amylase. Biochim Biophys Acta Gen Subj 2005; 1723:184-91. [PMID: 15826839 DOI: 10.1016/j.bbagen.2005.03.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2004] [Revised: 02/26/2005] [Accepted: 03/03/2005] [Indexed: 10/25/2022]
Abstract
The thermal unfolding of Amy 34, a recombinant alpha-amylase from Bacillus halodurans, has been investigated using differential scanning calorimetry (DSC). The denaturation of Amy 34 involves irreversible processes with an apparent denaturation temperature (T(m)) of 70.8 degrees C at pH 9.0, with four transitions, as determined using multiple Gaussian curves. The T(m) increased by 5 degrees C in the presence of 100-fold molar excess of CaCl2 while the aggregation of Amy 34 was observed in the presence of 1000-fold molar excess of CaCl2. Increase in the calcium ion concentration from 1- to 5-fold molar excess resulted in an increase in calorimetric enthalpy (DeltaH(cal)), however, at higher concentrations of CaCl2 (up to 100-fold), DeltaH(cal) was found to decrease, accompanied by a decrease in entropy change (DeltaS), while the T(m) steadily increased. The presence of 100-fold excess of metal chelator, EDTA, resulted in a decrease in T(m) by 10.4 degrees C. T(m) was also decreased to 61.1 degrees C and 65.9 degrees C at pH 6.0 and pH 11.0, respectively.
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Affiliation(s)
- Suhaila O Hashim
- Department of Biotechnology, Center for Chemistry and Chemical Engineering, Lund University, Box 124, SE-221 00 Lund, Sweden.
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60
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Hagihara H. An Oxidation Stable and Chelator-resistant, Calcium-free .ALPHA.-Amylase from the Alkaliphilic Bacillus Isolate KSM-K38. J Appl Glycosci (1999) 2005. [DOI: 10.5458/jag.52.51] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022] Open
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61
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Nielsen AD, Pusey ML, Fuglsang CC, Westh P. A proposed mechanism for the thermal denaturation of a recombinant Bacillus halmapalus α-amylase—the effect of calcium ions. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2003; 1652:52-63. [PMID: 14580996 DOI: 10.1016/j.bbapap.2003.08.002] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The thermal stability of a recombinant alpha-amylase from Bacillus halmapalus alpha-amylase (BHA) has been investigated using circular dichroism spectroscopy (CD) and differential scanning calorimetry (DSC). This alpha-amylase is homologous to other Bacillus alpha-amylases where crystallographic studies have identified the existence of three calcium binding sites in the structure. Denaturation of BHA is irreversible with a T(m) of approximately 89 degrees C and DSC thermograms can be described using a one-step irreversible model. A 5 degrees C increase in T(m) in the presence of 10-fold excess CaCl(2) was observed. However, a concomitant increase in the tendency to aggregate was also observed. The presence of 30-40-fold excess calcium chelator (ethylenediaminetetraacetic acid (EDTA) or ethylene glycol-bis[beta-aminoethyl ether] N,N,N',N'-tetraacetic acid (EGTA)) results in a large destabilization of BHA, corresponding to about 40 degrees C lower T(m) as determined by both CD and DSC. Ten-fold excess EGTA reveals complex DSC thermograms corresponding to both reversible and irreversible transitions, which probably originate from different populations of BHA/calcium complexes. Combined interpretation of these observations and structural information on homologous alpha-amylases forms the basis for a suggested mechanism underlying the inactivation mechanism of BHA. The mechanism includes irreversible thermal denaturation of different BHA/calcium complexes and the calcium binding equilibria. Furthermore, the model accounts for a temperature-induced reversible structural change associated with calcium binding.
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Affiliation(s)
- Anders D Nielsen
- Department of Life Sciences and Chemistry, Roskilde University, P.O. Box 260, 1-Universitetsvej, DK-4000 Roskilde, Denmark
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62
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Nonaka T, Fujihashi M, Kita A, Hagihara H, Ozaki K, Ito S, Miki K. Crystal structure of calcium-free alpha-amylase from Bacillus sp. strain KSM-K38 (AmyK38) and its sodium ion binding sites. J Biol Chem 2003; 278:24818-24. [PMID: 12719434 DOI: 10.1074/jbc.m212763200] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The crystal structure of a calcium-free alpha-amylase (AmyK38) from Bacillus sp. strain KSM-K38, which resists chelating reagents and chemical oxidants, has been determined by the molecular replacement method and refined to a crystallographic R-factor of 19.9% (R-free of 23.2%) at 2.13-A resolution. The main chain folding of AmyK38 is almost homologous to that of Bacillus licheniformis alpha-amylase. However, neither a highly conserved calcium ion, which is located at the interface between domains A and B, nor any other calcium ions appear to exist in the AmyK38 molecule, although three sodium ions were found, one of which is located at the position corresponding to that of a highly conserved calcium ion of other alpha-amylases. The existence of these sodium ions was crystallographically confirmed by the structures of three metal-exchanged and mutated enzymes. This is the first case in which the structure of the calcium-free alpha-amylase has been determined by crystallography, and it was suggested that these sodium ions, instead of calcium ions, are used to retain the structure and function of AmyK38.
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Affiliation(s)
- Tsuyoshi Nonaka
- Department of Chemistry, Graduate School of Science, Kyoto University, Sakyo-ku, Japan
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63
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64
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Linden A, Mayans O, Meyer-Klaucke W, Antranikian G, Wilmanns M. Differential regulation of a hyperthermophilic alpha-amylase with a novel (Ca,Zn) two-metal center by zinc. J Biol Chem 2003; 278:9875-84. [PMID: 12482867 DOI: 10.1074/jbc.m211339200] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The crystal structure of the alpha-amylase from the hyperthermophilic archaeon Pyrococcus woesei was solved in the presence of three inhibitors: acarbose, Tris, and zinc. In the absence of exogenous metals, this alpha-amylase bound 1 and 4 molar eq of zinc and calcium, respectively. The structure reveals a novel, activating, two-metal (Ca,Zn)-binding site and a second inhibitory zinc-binding site that is found in the -1 sugar-binding pocket within the active site. The data resolve the apparent paradox between the zinc requirement for catalytic activity and its strong inhibitory effect when added in molar excess. They provide a rationale as to why this alpha-amylase, in contrast to commercially available alpha-amylases, does not require the addition of metal ions for full catalytic activity, suggesting it as an ideal target to maximize the efficiency of industrial processes like liquefaction of starch.
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Affiliation(s)
- Anni Linden
- European Molecular Biology Laboratory, Notkestrasse 85, D-22603 Hamburg, Germany
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65
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TANAKA ATSUSHI, HOSHINO EIICHI. Secondary Calcium-Binding Parameter of Bacillus amyloliquefaciens .ALPHA.-Amylase Obtained from Inhibition Kinetics. J Biosci Bioeng 2003. [DOI: 10.1263/jbb.96.262] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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66
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Franco OL, Rigden DJ, Melo FR, Grossi-De-Sá MF. Plant alpha-amylase inhibitors and their interaction with insect alpha-amylases. EUROPEAN JOURNAL OF BIOCHEMISTRY 2002; 269:397-412. [PMID: 11856298 DOI: 10.1046/j.0014-2956.2001.02656.x] [Citation(s) in RCA: 248] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Insect pests and pathogens (fungi, bacteria and viruses) are responsible for severe crop losses. Insects feed directly on the plant tissues, while the pathogens lead to damage or death of the plant. Plants have evolved a certain degree of resistance through the production of defence compounds, which may be aproteic, e.g. antibiotics, alkaloids, terpenes, cyanogenic glucosides or proteic, e.g. chitinases, beta-1,3-glucanases, lectins, arcelins, vicilins, systemins and enzyme inhibitors. The enzyme inhibitors impede digestion through their action on insect gut digestive alpha-amylases and proteinases, which play a key role in the digestion of plant starch and proteins. The natural defences of crop plants may be improved through the use of transgenic technology. Current research in the area focuses particularly on weevils as these are highly dependent on starch for their energy supply. Six different alpha-amylase inhibitor classes, lectin-like, knottin-like, cereal-type, Kunitz-like, gamma-purothionin-like and thaumatin-like could be used in pest control. These classes of inhibitors show remarkable structural variety leading to different modes of inhibition and different specificity profiles against diverse alpha-amylases. Specificity of inhibition is an important issue as the introduced inhibitor must not adversely affect the plant's own alpha-amylases, nor the nutritional value of the crop. Of particular interest are some bifunctional inhibitors with additional favourable properties, such as proteinase inhibitory activity or chitinase activity. The area has benefited from the recent determination of many structures of alpha-amylases, inhibitors and complexes. These structures highlight the remarkable variety in structural modes of alpha-amylase inhibition. The continuing discovery of new classes of alpha-amylase inhibitor ensures that exciting discoveries remain to be made. In this review, we summarize existing knowledge of insect alpha-amylases, plant alpha-amylase inhibitors and their interaction. Positive results recently obtained for transgenic plants and future prospects in the area are reviewed.
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Affiliation(s)
- Octávio L Franco
- Centro Nacional de Recursos Genéticos e Biotecnologia, Cenargen/Embrapa, Brasília-DF, Brazil.
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67
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Hagihara H, Hayashi Y, Endo K, Igarashi K, Ozawa T, Kawai S, Ozaki K, Ito S. Deduced amino-acid sequence of a calcium-free alpha-amylase from a strain of Bacillus: implications from molecular modeling of high oxidation stability and chelator resistance of the enzyme. EUROPEAN JOURNAL OF BIOCHEMISTRY 2001; 268:3974-82. [PMID: 11453991 DOI: 10.1046/j.1432-1327.2001.02308.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Alkaline alpha-amylase (AmyK38) from the alkaliphilic Bacillus sp. strain KSM-K38 is a unique enzyme in that it is highly chelator-resistant and oxidatively stable [Hagihara, H., Igarashi, K., Hayashi, Y., Endo, K., Ikawa-Kitayama, K., Ozaki, K., Kawai, S. & Ito, S. (2001) Appl. Environ. Microbiol. 67, 1744-1750]. This enzyme was found to contain no Ca and require Na (or monovalent cations) for manifestation of activity. The nucleotide sequence of the gene for the novel enzyme was determined, and it harbored an ORF of 1503 bp encoding the enzyme of 501 amino acids, including a 21-amino-acid signal peptide. The deduced amino-acid sequence of the mature enzyme (55 097 Da) showed moderate homology to those of alpha-amylases from Bacillus licheniformis, Bacillus stearothermophilus and Bacillus amyloliquefaciens, with approximately 63% identity. A methionine residue, which is conserved and susceptible to chemical oxidation, was replaced with leucine in AmyK38. Moreover, many conserved residues that are crucial ligands for Ca were replaced with other amino acids, thereby leading to loss of the Ca coordination geometries. By building a molecular model, we showed the calcium-independent, oxidatively stable active-site topology and structural integrity of AmyK38.
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Affiliation(s)
- H Hagihara
- Tochigi Research Laboratories of Kao Corporation, Ichikai, Haga, Japan
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68
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Hagihara H, Igarashi K, Hayashi Y, Endo K, Ikawa-Kitayama K, Ozaki K, Kawai S, Ito S. Novel alpha-amylase that is highly resistant to chelating reagents and chemical oxidants from the alkaliphilic Bacillus isolate KSM-K38. Appl Environ Microbiol 2001; 67:1744-50. [PMID: 11282629 PMCID: PMC92793 DOI: 10.1128/aem.67.4.1744-1750.2001] [Citation(s) in RCA: 93] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2000] [Accepted: 02/02/2001] [Indexed: 11/20/2022] Open
Abstract
A novel alpha-amylase (AmyK38) was found in cultures of an alkaliphilic Bacillus isolate designated KSM-K38. Based on the morphological and physiological characteristics and phylogenetic position as determined by 16S ribosomal DNA gene sequencing and DNA-DNA reassociation analysis, it was suggested that the isolate was a new species of the genus Bacillus. The enzyme had an optimal pH of 8.0 to 9.5 and displayed maximum catalytic activity at 55 to 60 degrees C. The apparent molecular mass was approximately 55 kDa, as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and the isoelectric point was around pH 4.2. This enzyme efficiently hydrolyzed various carbohydrates to yield maltotriose, maltohexaose, maltoheptaose, and, in addition, maltose as major end products after completion of the reaction. The activity was not prevented at all by EDTA and EGTA at concentrations as high as 100 mM. Moreover, AmyK38 was highly resistant to chemical oxidation and maintained more than 80% of its original activity even after incubation for 1 h in the presence of excess H2O2 (1.8 M).
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Affiliation(s)
- H Hagihara
- Tochigi Research Laboratories of Kao Corporation, 2606 Akabane, Ichikai, Haga, Tochigi 321-3497, Japan.
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69
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Nielsen JE, Borchert TV. Protein engineering of bacterial alpha-amylases. BIOCHIMICA ET BIOPHYSICA ACTA 2000; 1543:253-274. [PMID: 11150610 DOI: 10.1016/s0167-4838(00)00240-5] [Citation(s) in RCA: 169] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
alpha-Amylases constitute a very diverse family of glycosyl hydrolases that cleave alpha1-->4 linkages in amylose and related polymers. Recent structural and mutagenic studies of archeael, mammalian and bacterial alpha-amylases have resulted in a wealth of information on the catalytic mechanism and on the structural features of this enzyme class. Because of their high thermo-stability, the Bacillus alpha-amylases have found widespread use in industrial processes, and much attention has been devoted to optimising these enzymes for the very harsh conditions encountered there. Stability has been a major area of focus in this respect, and several remarkably stable bacterial alpha-amylases have been produced by bioengineering techniques. Protein engineering studies of pH-activity profiles and of substrate specificities have also been initiated, although without much success. In the coming years it is likely, however, that the focus of alpha-amylase engineering will shift from engineering stability to these new areas.
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Affiliation(s)
- J E Nielsen
- EMBL, Meyerhofstrasse 1, 69117 Heidelber, Germany
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70
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Bautista LF, Martínez M, Aracil J. Modeling of the Adsorption of α-Amylase in Batch Stirred Tank. Ind Eng Chem Res 2000. [DOI: 10.1021/ie000262+] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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71
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Declerck N, Machius M, Wiegand G, Huber R, Gaillardin C. Probing structural determinants specifying high thermostability in Bacillus licheniformis alpha-amylase. J Mol Biol 2000; 301:1041-57. [PMID: 10966804 DOI: 10.1006/jmbi.2000.4025] [Citation(s) in RCA: 108] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Bacillus licheniformis alpha-amylase (BLA) is a starch-degrading enzyme that is highly thermostable although it is produced by a rather mesophilic organism. Over the last decade, the origin of BLA thermal properties has been extensively investigated in both academic and industrial laboratories, yet it is poorly understood. Here, we have used structure-based mutagenesis in order to probe the role of amino acid residues previously proposed as being important for BLA thermostability. Residues involved in salt-bridges, calcium binding or potential deamidation processes have been selected and replaced with various amino acids using a site-directed mutagenesis method, based on informational suppression. A total of 175 amylase variants were created and analysed in vitro. Active amylase variants were tested for thermostability by measuring residual activities after incubation at high temperature. Out of the 15 target residues, seven (Asp121, Asn126, Asp164, Asn192, Asp200, Asp204 and Ala269) were found to be particularly intolerant to any amino acid substitutions, some of which lead to very unstable mutant enzymes. By contrast, three asparagine residues (Asn172, Asn188 and Asn190) could be replaced with amino acid residues that significantly increase the thermostability compared to the wild-type enzyme. The highest stabilization event resulted from the substitution of phenylalanine in place of asparagine at position 190, leading to a sixfold increase of the enzyme's half-life at 80 degrees C (pH 5.6, 0.1 mM CaCl(2)). These results, combined with those of previous mutational analyses, show that the structural determinants contributing to the overall thermostability of BLA concentrate in domain B and at its interface with the central A domain. This region contains a triadic Ca-Na-Ca metal-binding site that appears extremely sensitive to any modification that may alter or reinforce the network of electrostatic interactions entrapping the metal ions. In particular, a loop spanning from residue 178 to 199, which undergoes pronounced conformational changes upon removal of calcium, appears to be the key feature for maintaining the enzyme structural integrity. Outside this region, most salt-bridges that were destroyed by mutations were found to be dispensable, except for an Asp121-Arg127 salt-bridge that contributes to the enhanced thermostability of BLA compared to other homologous bacterial alpha-amylases. Finally, our studies demonstrate that the natural resistance of BLA against high temperature is not optimized and can be enhanced further through various means, including the removal of possibly deamidating residues.
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Affiliation(s)
- N Declerck
- Génétique Moléculaire et Cellulaire, INRA-UMR216 and CNRS-URA1925 INA-PG, Thiverval-Grignon, F-78850, France.
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72
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Mohamed SA. alpha-Amylase from developing embryos of the camel tick Hyalomma dromedarii. Comp Biochem Physiol B Biochem Mol Biol 2000; 126:99-108. [PMID: 10825669 DOI: 10.1016/s0305-0491(00)00165-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
alpha-Amylase activity in the camel tick Hyalomma dromedarii was followed throughout embryogenesis. During purification of alpha-amylase III to homogeneity, ion exchange chromatography lead to four separate forms (termed I, II, III and IV). alpha-Amylase III with the highest specific activity was pure after chromatography on Sephacryl S-300. The molecular mass of alpha-amylase III was 106 kDa for the native enzyme, composed of two subunits of 43 and 66 kDa, respectively. alpha-Amylase had a value of 10 mg starch/ml. Varying alpha-amylase activity was detected when supplied with various substrates. alpha-Amylase III had a temperature optimum at 40 degrees C with heat stability up to 50 degrees C, and a pH optimum of 7.0. The enzyme activity was activated by CaCl2, MgCl2 and NaNO3, but not activated by NaCl, p-CMB, N-ethylmaleimide and iodoacetamide. EDTA and beta-mercaptoethanol strongly inhibited activity.
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Affiliation(s)
- S A Mohamed
- Molecular Biology Department, National Research Centre, Dokki, Cairo, Egypt
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73
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Lauer I, Bonnewitz B, Meunier A, Beverini M. New approach for separating Bacillus subtilis metalloprotease and alpha-amylase by affinity chromatography and for purifying neutral protease by hydrophobic chromatography. JOURNAL OF CHROMATOGRAPHY. B, BIOMEDICAL SCIENCES AND APPLICATIONS 2000; 737:277-84. [PMID: 10681065 DOI: 10.1016/s0378-4347(99)00482-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Proteases are commonly used in the biscuit and cracker industry as processing aids. They cause moderate hydrolysis of gluten proteins and improve dough rheology to better control product texture and crunchiness. Commercial bacterial proteases are derived from Bacillus fermentation broth. As filtration and ultrafiltration are carried out as the only recovery steps, these preparations contain also alpha-amylase and beta-glucanase as the main side activities. The aim of this study is to purify and characterize the Bacillus subtilis metalloprotease from a commercial preparation, in order to study separately the impact of the protease activity with regards to its functionality on biscuit properties. Purification was achieved by means of affinity chromatography on Cibacron Blue and HIC as a polishing step. Affinity appeared to be the most appropriate matrix for large scale purification while ion exchange chromatography was inefficient in terms of recovery yields. The crude product was first loaded on a Hi Trap Blue column (34 microm, Pharmacia Biotech); elution was carried out with a gradient of NaCl in the presence of 1 mM ZnCl2. This step was only efficient in the presence of Zn cations, because this salt promoted both protease stabilization resulting in high recovery yields and also complexation of amylase units into dimers resulting in amylase retention on the column and a better separation of the 3 activities. Beta-glucanase was mostly non retained on the column and a part was coeluted with the protease. This protease fraction was then loaded on a Resource Phe column (15 microm, Pharmacia Biotech) in a last step of polishing. Elution was carried out with a linear gradient of 100-0% ammonium sulfate 1.3 M; protease was eluted at the beginning of the gradient and well separated from amylase and glucanase trace impurities. The homogeneity of the purified protease was confirmed by SDS-PAGE, which showed that its MW was about 38. pH and temperature optima were also determined on the fraction.
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Affiliation(s)
- I Lauer
- Centre de Recherche TEPRAL, Branche Boissons du Groupe Danone, Strasbourg, France.
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74
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SRI RAM J, BIER M, MAURER PH. Chemical modifications of proteins and their significance in enzymology, immunochemistry, and related subjects. ACTA ACUST UNITED AC 1998; 24:105-60. [PMID: 13915994 DOI: 10.1002/9780470124888.ch3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/24/2023]
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75
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WATSON PR, JEANES A. Problems involved in dialyzing low concentrations of inorganic pyrophosphate. Anal Biochem 1998; 4:505-8. [PMID: 13999216 DOI: 10.1016/0003-2697(62)90130-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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76
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Stephenson K, Harwood CR. Influence of a cell-wall-associated protease on production of alpha-amylase by Bacillus subtilis. Appl Environ Microbiol 1998; 64:2875-81. [PMID: 9687444 PMCID: PMC106786 DOI: 10.1128/aem.64.8.2875-2881.1998] [Citation(s) in RCA: 69] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
AmyL, an extracellular alpha-amylase from Bacillus licheniformis, is resistant to extracellular proteases secreted by Bacillus subtilis during growth. Nevertheless, when AmyL is produced and secreted by B. subtilis, it is subject to considerable cell-associated proteolysis. Cell-wall-bound proteins CWBP52 and CWBP23 are the processed products of the B. subtilis wprA gene. Although no activity has been ascribed to CWBP23, CWBP52 exhibits serine protease activity. Using a strain encoding an inducible wprA gene, we show that a product of wprA, most likely CWBP52, is involved in the posttranslocational stability of AmyL. A construct in which wprA is not expressed exhibits an increased yield of alpha-amylase. The potential role of wprA in protein secretion is discussed, together with implications for the use of B. subtilis and related bacteria as hosts for the secretion of heterologous proteins.
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Affiliation(s)
- K Stephenson
- School of Microbiological, Immunological, and Virological Sciences, The Medical School, University of Newcastle upon Tyne, Newcastle upon Tyne, NE2 4HH, United Kingdom
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77
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Igarashi K, Hatada Y, Ikawa K, Araki H, Ozawa T, Kobayashi T, Ozaki K, Ito S. Improved thermostability of a Bacillus alpha-amylase by deletion of an arginine-glycine residue is caused by enhanced calcium binding. Biochem Biophys Res Commun 1998; 248:372-7. [PMID: 9675143 DOI: 10.1006/bbrc.1998.8970] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
alpha-Amylase from alkaliphilic Bacillus KSM-1378 (LAMY) is a novel semi-alkaline enzyme which has a high specific activity, a value 5-fold higher than that of a Bacillus licheniformis enzyme at alkaline pH. Thermostability of this enzyme could be improved by deletion of the Arg181-Gly182 residue by means of site-directed mutagenesis. The wild-type and engineered LAMYs were very similar with respect to specific activity, pH-activity curve, temperature-activity curve, susceptibility to inhibitors, and pattern of hydrolysis products from soluble starch and maltooligosaccharides. However, the engineered enzyme also acquired increased pH stability and resistance to sodium dodecyl sulfate and especially chelating reagents, such as ethylenediaminetetraacetate and ethyleneglycol-bis (beta-aminoethylether)tetraacetate. This is the first report that thermostability of alpha-amylase is improved by enhanced calcium binding to the enzyme molecule.
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Affiliation(s)
- K Igarashi
- Tochigi Research Laboratories of Kao Corporation, 2606 Akabane, Ichikai, Haga, Tochigi, 321-3497, Japan
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78
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Strobl S, Maskos K, Betz M, Wiegand G, Huber R, Gomis-Rüth FX, Glockshuber R. Crystal structure of yellow meal worm alpha-amylase at 1.64 A resolution. J Mol Biol 1998; 278:617-28. [PMID: 9600843 DOI: 10.1006/jmbi.1998.1667] [Citation(s) in RCA: 86] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The three-dimensional structure of the alpha-amylase from Tenebrio molitor larvae (TMA) has been determined by molecular replacement techniques using diffraction data of a crystal of space group P212121 (a=51.24 A; b=93.46 A; c=96.95 A). The structure has been refined to a crystallographic R-factor of 17.7% for 58,219 independent reflections in the 7.0 to 1.64 A resolution range, with root-mean-square deviations of 0.008 A for bond lengths and 1.482 degrees for bond angles. The final model comprises all 471 residues of TMA, 261 water molecules, one calcium cation and one chloride anion. The electron density confirms that the N-terminal glutamine residue has undergone a post-transitional modification resulting in a stable 5-oxo-proline residue. The X-ray structure of TMA provides the first three-dimensional model of an insect alpha-amylase. The monomeric enzyme exhibits an elongated shape approximately 75 Ax46 Ax40 A and consists of three distinct domains, in line with models for alpha-amylases from microbial, plant and mammalian origin. However, the structure of TMA reflects in the substrate and inhibitor binding region a remarkable difference from mammalian alpha-amylases: the lack of a highly flexible, glycine-rich loop, which has been proposed to be involved in a "trap-release" mechanism of substrate hydrolysis by mammalian alpha-amylases. The structural differences between alpha-amylases of various origins might explain the specificity of inhibitors directed exclusively against insect alpha-amylases.
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Affiliation(s)
- S Strobl
- Institut für Molekularbiologie und Biophysik, Eidenössische Technische Hochschule Hönggerberg, Zürich, CH-8093, Switzerland
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79
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Machius M, Declerck N, Huber R, Wiegand G. Activation of Bacillus licheniformis alpha-amylase through a disorder-->order transition of the substrate-binding site mediated by a calcium-sodium-calcium metal triad. Structure 1998; 6:281-92. [PMID: 9551551 DOI: 10.1016/s0969-2126(98)00032-x] [Citation(s) in RCA: 164] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
BACKGROUND The structural basis as to how metals regulate the functional state of a protein by altering or stabilizing its conformation has been characterized in relatively few cases because the metal-free form of the protein is often partially disordered and unsuitable for crystallographic analysis. This is not the case, however, for Bacillus licheniformis alpha-amylase (BLA) for which the structure of the metal-free form is available. BLA is a hyperthermostable enzyme which is widely used in biotechnology, for example in the breakdown of starch or as a component of detergents. The determination of the structure of BLA in the metal-containing form, together with comparisons to the apo enzyme, will help us to understand the way in which metal ions can regulate enzyme activity. RESULTS We report here the crystal structure of native, metal-containing BLA. The structure shows that the calcium-binding site which is conserved in all alpha-amylases forms part of an unprecedented linear triadic metal array, with two calcium ions flanking a central sodium ion. A region around the metal triad comprising 21 residues exhibits a conformational change involving a helix unwinding and a disorder-->order transition compared to the structure of metal-free BLA. Another calcium ion, not previously observed in alpha-amylases, is located at the interface between domains A and C. CONCLUSIONS We present a structural description of a major conformational rearrangement mediated by metal ions. The metal induced disorder-->order transition observed in BLA leads to the formation of the extended substrate-binding site and explains on a structural level the calcium dependency of alpha-amylases. Sequence comparisons indicate that the unique Ca-Na-Ca metal triad and the additional calcium ion located between domains A and C might be found exclusively in bacterial alpha-amylases which show increased thermostability. The information presented here may help in the rational design of mutants with enhanced performance in biotechnological applications.
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Affiliation(s)
- M Machius
- Max-Planck-Institut für Biochemie, Planegg-Martinsried, Germany.
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80
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Lorentz K. Approved recommendation on IFCC methods for the measurement of catalytic concentration of enzymes. Part 9. IFCC method for alpha-amylase (1,4-alpha-D-glucan 4-glucanohydrolase, EC 3.2.1.1). International Federation of Clinical Chemistry and Laboratory Medicine (IFCC). Committee on Enzymes. Clin Chem Lab Med 1998; 36:185-203. [PMID: 9589808 DOI: 10.1515/cclm.1998.034] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- K Lorentz
- Institut für Klinische Chemie, Medizinische Universität Lübeck, Germany
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81
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Abstract
The presence of unique zinc-binding proteins in human saliva is well documented. These observations have not, however, been extended to other species. The rat has been used extensively to study the salivary gland and its secretion, and it is therefore important to determine if the spectrum of zinc-binding proteins in this experimental model resembles that found in humans. To begin the analysis of zinc-binding proteins in stimulated rat parotid saliva, the saliva was fractionated by DEAE Sephadex and Sepharose 6B chaelate chromatography and the protein patterns analysed by electrophoresis. Zinc-binding proteins from the parotid saliva were identified by incubating Western blots with 65Zn and identifying any bound zinc by autoradiography. Comparison of the autoradiograms with the Coomassie blue-stained filter revealed several proteins with zinc-binding capacity. Isolation of the major zinc-binding proteins revealed an amino acid composition of proline 28%, glutamine 19% and glycine 15%, which is consistent with the amino acid composition of rat salivary acidic proline-rich protein. In addition to the proline-rich proteins, one other zinc-binding protein was analysed. The N-terminal sequence of this protein was found to bear a striking similarity (16 out of 20 amino acids) to secreted carbonic anhydrase VI of the mouse, a known zinc-binding protein. These data demonstrate that rat acidic proline-rich proteins, having an amino acid composition similar to that in humans, have zinc-binding potential. The data also confirm previous reports suggesting secreted carbonic anhydrase in rat parotid saliva.
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Affiliation(s)
- K R Etzel
- Department of Microbiology/Biochemistry, University of Pittsburgh School of Dental Medicine 15261-1964. USA
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82
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83
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Moriyama T, Ikeda H. Hydrolases acting on glycosidic bonds: chromatographic and electrophoretic separations. JOURNAL OF CHROMATOGRAPHY. B, BIOMEDICAL APPLICATIONS 1996; 684:201-16. [PMID: 8906474 DOI: 10.1016/0378-4347(96)00148-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
We describe analyses of unusual human alpha-amylase, performed in our laboratory and review available methods for amylase study. Electrophoretic and chromatographic methods provide an effective means for the analysis of amylase isoenzymes and unusual amylase. The recent identification of a selective inhibitor and a monoclonal antibody to amylase isoenzyme contributes to rapid routine clinical assays of amylase isoenzymes. However unusual amylases such as variants, macroamylasemia and sialyl salivary-type amylasemia cannot be detected by those conventional methods. The unusual amylases can only be detected by electrophoresis and can be easily characterized by combination study with chromatographic methods. Electrophoretic and chromatographic methods are universal means to validate unusual amylases found in patient sera. Further basal studies are needed to define the roles of salivary amylase in exocrine fluids using those separation techniques.
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Affiliation(s)
- T Moriyama
- Clinical Laboratories, Asahikawa Medical College Hospital, Japan
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84
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Tessier AJ, Dombi GW, Bouwman DL. Thermostability of purified human pancreatic alpha-amylase is increased by the combination of Ca2+ and human serum albumin. Clin Chim Acta 1996; 252:11-20. [PMID: 8814357 DOI: 10.1016/0009-8981(96)06316-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Pancreatic fluid from a patient with a post operative pancreatic fistula was used to isolate human alpha-amylase by means of acarbose affinity chromatography. Amylase thermostability was measured in 4 solutions: (1) EDTA-dialyzed; (2) dialyzed solution plus 0.15 mmol/l (1.0 g/dl) human serum albumin; (3) dialyzed solution plus 0.25 mmol/l (1.0 mg/dl) calcium ions; and (4) dialyzed solution with both human serum albumin and calcium ions. Amylase activity was measured at predetermined times in samples heated to 60 degrees C. Thermostability was characterized by t1/2, the time to 50% initial amylase enzyme activity. In the dialyzed solution t1/2 was 0.75 +/- 0.19 min. This rose to 1.62 +/- 0.34 min with added human serum albumin, and to 8.24 +/- 0.13 min with added calcium ions. The combination of human serum albumin and calcium ions resulted in a synergistic increase of t1/2 to 180 +/- 26 min. These findings support our contention that human serum albumin, calcium ions and possibly other body fluid constituents must be considered in any utility involving amylase thermostability as a clinically relevant diagnostic marker.
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Affiliation(s)
- A J Tessier
- Harper Hospital, Department of Surgery, Detroit, MI 48201, USA. atessie/cms.cc.wayne.edu
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85
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Esteve-Romero JS, Bossi A, Righetti PG. Purification of thermamylase in multicompartment electrolyzers with isoelectric membranes: the problem of protein solubility. Electrophoresis 1996; 17:1242-7. [PMID: 8855411 DOI: 10.1002/elps.1150170712] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The main alpha-amylase from Bacillus licheniformis (called thermamylase because of its resistance to high temperatures, 90 degrees C) has been subjected to purification by isoelectric focusing in multicompartment electrolyzers with isoelectric membranes. The enzyme tended to precipitate, producing severe smears in proximity of its pI value (7.18). Solubility could not be ameliorated by any of the known means typically adopted in isoelectric focusing and compatible with enzyme activity, such as addition of neutral and zwitterionic surfactants (e.g., Nonidet, 3-[(3-cholamidopropyl)dimethylammonio]-1-propane-sulfonate, up to 2%), mixed hydro-organic solvents (glycerol, ethylene glycol, propylene glycol) and addition of zwitterions unable to form micelles, such as taurine. However, addition of sugars, notably saccharose, sorbitol, and, to a lesser extent, sorbose, greatly improved protein solubility in the pI proximity. The improvement was dramatic if these sugars were admixed with 0.2 M taurine. Additionally, the increment of solubility (which occurred when reaching a level of 40% of the different sugars) was accompanied by a large pI shift, typically reducing the pI value by as much as 0.4 pH units (e.g., from a pI of 7.18 in the absence of additives to a pI of 6.80 in presence of a mixture of 40% sucrose and 0.2 M taurine, the best solubilizer in all the series investigated). This apparent pI shift was not due to a change of pH gradient caused by the presence of additives, since pH measurements in the absence as well as presence of additives gave identical results. The results are explained by the theory of Timasheff and Arakawa on stabilization of protein structure by solvents: sugars (at ca. 1 M concentration) and zwitterions such as taurine belong to class I stabilizers, characterized by negative binding to proteins and by increasing the surface tension of water. As a result, the protein is in a state of "superhydration", which might prevent binding to Immobilines in the gel matrix and might alter some pKs on the protein surface. In solutions of 40% saccharose and 0.2 M taurine, thermamylase could be successfully purified to a single isoelectric and isoionic band in the multicompartment electrolyzer.
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Affiliation(s)
- J S Esteve-Romero
- Universitat Jaume I, Department de Ciencies Experimentals, Castello, Spain
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86
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Gilles C, Astier JP, Marchis-Mouren G, Cambillau C, Payan F. Crystal structure of pig pancreatic alpha-amylase isoenzyme II, in complex with the carbohydrate inhibitor acarbose. EUROPEAN JOURNAL OF BIOCHEMISTRY 1996; 238:561-9. [PMID: 8681972 DOI: 10.1111/j.1432-1033.1996.0561z.x] [Citation(s) in RCA: 111] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Two different crystal forms of pig pancreatic alpha-amylase isoenzyme II (PPAII), free and complexed to a carbohydrate inhibitor (acarbose), have been compared together and to previously reported structures of PPAI. A crystal form obtained at 4 degrees C, containing nearly 72% solvent, made it possible to obtain a new complex with acarbose, different from a previous one obtained at 20 degrees C [Qian, M., Buisson, G., Duée, E., Haser, H. & Payan, F. (1994) Biochemistry 33, 6284-6294]. In the present form, six contiguous subsites of the enzyme active site are occupied by the carbohydrate ligand; the structural data indicate that the binding site is capable of holding more than the five glucose units of the scheme proposed through kinetic studies. A monosaccharide ring bridging two protein molecules related by the crystal packing is located on the surface, at a distance of 2.0 nm from the reducing end of the inhibitor ligand; the symmetry-related glucose ring in the crystal lattice is found 1.5 nm away from the non-reducing end of the inhibitor ligand.
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Affiliation(s)
- C Gilles
- LCCMB-IBSM, CNRS, Marseille, France
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87
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Paech C, Goddette DW, Christianson T, Wilson CR. Unusual ligand binding at the active site domain of an engineered mutant of subtilisin BL. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 1996; 379:257-68. [PMID: 8796330 DOI: 10.1007/978-1-4613-0319-0_27] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
As an attempt to recruit the third calcium binding site of thermitase into subtilisin BL, a Bacillus lentus alkaline protease (BLAP), the amino acid sequence from position 50 to 60 and position 92 was modified to the equivalent amino acids in thermitase. The resulting protein, designated BLAPm109, exhibited unusual biochemical features. Peptide mapping and gel electrophoresis revealed that two protein species co-purify in a ratio of about 1:1. Form 1 consisted of a single polypeptide of 269 amino acid residues. Form 2 was the same protein but with an internal peptide bond cleavage at the C-terminus of position 54. On electropherograms a dimer of Form 1 and Form 2 was also detectable. A zymogram showed that all three molecular species were catalytically active. From this protein mixture, crystals suitable for X-ray analysis were nevertheless obtained. SDS-PAGE of protein recovered from a crystal revealed that only Form 2 appears. in the crystal. The space group for this crystal was P21 with unit cell dimensions of a=42 angstroms, b=58 angstroms, c=47 angstroms and beta = 106.3 degrees. Examination of the preliminary electron density map revealed that the "thermitase loop" from 50 to 60 departs from the surface of the protein and winds through the active site of a symmetry-related copy of the asymmetric unit.
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Affiliation(s)
- C Paech
- COGNIS, Inc., Santa Rosa, California 95407, USA
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88
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Brayer GD, Luo Y, Withers SG. The structure of human pancreatic alpha-amylase at 1.8 A resolution and comparisons with related enzymes. Protein Sci 1995; 4:1730-42. [PMID: 8528071 PMCID: PMC2143216 DOI: 10.1002/pro.5560040908] [Citation(s) in RCA: 257] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The structure of human pancreatic alpha-amylase has been determined to 1.8 A resolution using X-ray diffraction techniques. This enzyme is found to be composed of three structural domains. The largest is Domain A (residues 1-99, 169-404), which forms a central eight-stranded parallel beta-barrel, to one end of which are located the active site residues Asp 197, Glu 233, and Asp 300. Also found in this vicinity is a bound chloride ion that forms ligand interactions to Arg 195, Asn 298, and Arg 337. Domain B is the smallest (residues 100-168) and serves to form a calcium binding site against the wall of the beta-barrel of Domain A. Protein groups making ligand interactions to this calcium include Asn 100, Arg 158, Asp 167, and His 201. Domain C (residues 405-496) is made up of anti-parallel beta-structure and is only loosely associated with Domains A and B. It is notable that the N-terminal glutamine residue of human pancreatic alpha-amylase undergoes a posttranslational modification to form a stable pyrrolidone derivative that may provide protection against other digestive enzymes. Structure-based comparisons of human pancreatic alpha-amylase with functionally related enzymes serve to emphasize three points. Firstly, despite this approach facilitating primary sequence alignments with respect to the numerous insertions and deletions present, overall there is only approximately 15% sequence homology between the mammalian and fungal alpha-amylases. Secondly, in contrast, these same studies indicate that significant structural homology is present and of the order of approximately 70%. Thirdly, the positioning of Domain C can vary considerably between alpha-amylases. In terms of the more closely related porcine enzyme, there are four regions of polypeptide chain (residues 237-250, 304-310, 346-354, and 458-461) with significantly different conformations from those in human pancreatic alpha-amylase. At least two of these could play a role in observed differential substrate and cleavage pattern specificities between these enzymes. Similarly, amino acid differences between human pancreatic and salivary alpha-amylases have been localized and a number of these occur in the vicinity of the active site.
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Affiliation(s)
- G D Brayer
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, Canada
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89
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Casset F, Imberty A, Haser R, Payan F, Perez S. Molecular modelling of the interaction between the catalytic site of pig pancreatic alpha-amylase and amylose fragments. EUROPEAN JOURNAL OF BIOCHEMISTRY 1995; 232:284-93. [PMID: 7556163 DOI: 10.1111/j.1432-1033.1995.tb20810.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
A stereo chemical refinement of the crystalline complex between porcine pancreatic alpha-amylase and a pseudopentasaccharide from the amylostatin family has been performed through molecular mechanics calculations, using a set of parameters appropriate for protein and protein-carbohydrate interactions. The refinement provided a starting point for docking a maltopentaose moiety within the catalytic site, in the absence of water. A thorough exploration of the different orientations and conformations of maltopentaose established the sense of binding of the amylosic substrate in the amylase cleft. After optimising the geometry of the binding site, the conformations adopted by the four contiguous linkages could be rationalised by considering the environment, either hydrophobic or hydrophilic, of the different glucose moieties. Seemingly, details of the non-bonded interactions (hydrogen bonds, van der Waals and stacking interactions) that underlie this molecular recognition have been established. In particular, it was confirmed that the three acidic amino acids of the catalytic site (Asp197, Asp300 and Glu233) are close to their glucosidic target, and that there is no steric reason to propose an alteration of the 4C1 conformation of the glucose residue prior to hydrolysis. However, in the absence of water molecules, it is difficult to elucidate the details of the catalysis. Additional macroscopic information has been gained, such as the impossibility to fit a double-helical arrangement of amylose chains in the amylasic cleft. This explains why some native starches containing such motifs resist amylolytic enzymes. Tentative models involving longer amylosic chains have been elaborated, which extend our knowledge of the interaction and orientation of starch fragments in the vicinity of the hydrolytic sites.
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Affiliation(s)
- F Casset
- Institut National de la Recherche Agronomique, Nantes, France
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90
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Qian M, Haser R, Payan F. Carbohydrate binding sites in a pancreatic alpha-amylase-substrate complex, derived from X-ray structure analysis at 2.1 A resolution. Protein Sci 1995; 4:747-55. [PMID: 7613472 PMCID: PMC2143103 DOI: 10.1002/pro.5560040414] [Citation(s) in RCA: 82] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The X-ray structure analysis of a crystal of pig pancreatic alpha-amylase (PPA, EC 3.2.1.1.) that was soaked with the substrate maltopentaose showed electron density corresponding to two independent carbohydrate recognition sites on the surface of the molecule. Both binding sites are distinct from the active site described in detail in our previous high-resolution study of a complex between PPA and a carbohydrate inhibitor (Qian M, Buisson G, Duée E, Haser H, Payan F, 1994, Biochemistry 33:6284-6294). One of the binding sites previously identified in a 5-A-resolution electron density map, lies at a distance of 20 A from the active site cleft and can accommodate two glucose units. The second affinity site for sugar units is located close to the calcium binding site. The crystal structure of the maltopentaose complex was refined at 2.1 A resolution, to an R-factor of 17.5%, with an RMS deviation in bond distances of 0.007 A. The model includes all 496 residues of the enzyme, 1 calcium ion, 1 chloride ion, 425 water molecules, and 3 bound sugar rings. The binding sites are characterized and described in detail. The present complex structure provides the evidence of an increased stability of the structure upon interaction with the substrate and allows identification of an N-terminal pyrrolidonecarboxylic acid in PPA.
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Affiliation(s)
- M Qian
- LCCMB-CNRS, URA 1296, Université Aix-Marseille II, Faculté de Médecine Nord Bd Pierre Dramard, France
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91
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Linse S, Forsén S. Determinants that govern high-affinity calcium binding. ADVANCES IN SECOND MESSENGER AND PHOSPHOPROTEIN RESEARCH 1995; 30:89-151. [PMID: 7695999 DOI: 10.1016/s1040-7952(05)80005-9] [Citation(s) in RCA: 106] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Affiliation(s)
- S Linse
- Lund University, Chemical Centre, Sweden
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92
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Qian M, Haser R, Buisson G, Duée E, Payan F. The active center of a mammalian alpha-amylase. Structure of the complex of a pancreatic alpha-amylase with a carbohydrate inhibitor refined to 2.2-A resolution. Biochemistry 1994; 33:6284-94. [PMID: 8193143 DOI: 10.1021/bi00186a031] [Citation(s) in RCA: 220] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
An X-ray structure analysis of a crystal of pig pancreatic alpha-amylase (EC 3.2.1.1) that was soaked with acarbose (a pseudotetrasaccharide alpha-amylase inhibitor) showed electron density corresponding to five fully occupied subsites in the active site. The crystal structure was refined to an R-factor of 15.3%, with a root mean square deviation in bond distances of 0.015 A. The model includes all 496 residues of the enzyme, one calcium ion, one chloride ion, 393 water molecules, and five bound sugar rings. The pseudodisaccharide acarviosine that is the essential structural unit responsible for the activity of all inhibitors of the acarbose type was located at the catalytic center. The carboxylic oxygens of the catalytically competent residues Glu233 and Asp300 form hydrogen bonds with the "glycosidic" NH group of the acarviosine group. The third residue of the catalytic triad Asp197 is located on the opposite side of the inhibitor binding cleft with one of its carbonyl oxygens at a 3.3-A distance from the anomeric carbon C-1 of the inhibitor center. Binding of inhibitor induces structural changes at the active site of the enzyme. A loop region between residues 304 and 309 moves in toward the bound saccharide, the resulting maximal mainchain movement being 5 A for His305. The side chain of residue Asp300 rotates upon inhibitor binding and makes strong van der Waals contacts with the imidazole ring of His299. Four histidine residues (His101, His201, His299, and His305) are found to be hydrogen-bonded with the inhibitor. Many protein-inhibitor hydrogen bond interactions are observed in the complex structure, as is clear hydrophobic stacking of aromatic residues with the inhibitor surface. The chloride activator ion and structural calcium ion are hydrogen-bonded via their ligands and water molecules to the catalytic residues.
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Affiliation(s)
- M Qian
- LCCMB-CNRS, URA 1296, Faculté de Médecine Nord Bd Pierre Dramard, Marseille, France
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93
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HAGENIMANA VITAL, VÉZINA LOUISP, SIMARD RONALDE. Sweetpotato ?- and ?-Amylases: Characterization and Kinetic Studies with Endogenous Inhibitors. J Food Sci 1994. [DOI: 10.1111/j.1365-2621.1994.tb06970.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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94
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Babu K, Satyanarayana T. Extracellular calcium-inhibited alpha-amylase of Bacillus coagulans B 49. Enzyme Microb Technol 1993. [DOI: 10.1016/0141-0229(93)90056-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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95
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The purification and characterization of an extremely thermostable alpha-amylase from the hyperthermophilic archaebacterium Pyrococcus furiosus. J Biol Chem 1993. [DOI: 10.1016/s0021-9258(20)80538-9] [Citation(s) in RCA: 117] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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96
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Jones RL, Jacobsen JV. Regulation of synthesis and transport of secreted proteins in cereal aleurone. INTERNATIONAL REVIEW OF CYTOLOGY 1991; 126:49-88. [PMID: 2050500 DOI: 10.1016/s0074-7696(08)60682-8] [Citation(s) in RCA: 163] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Affiliation(s)
- R L Jones
- Department of Plant Biology, University of California, Berkeley 94720
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97
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Paquet V, Croux C, Goma G, Soucaille P. Purification and characterization of the extracellular alpha-amylase from Clostridium acetobutylicum ATCC 824. Appl Environ Microbiol 1991; 57:212-8. [PMID: 8967771 PMCID: PMC182687 DOI: 10.1128/aem.57.1.212-218.1991] [Citation(s) in RCA: 59] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
The extracellular alpha-amylase (1,4-alpha-D-glucanglucanohydrolase; EC 3.2.1.1) from Clostridium acetobutylicum ATCC 824 was purified to homogeneity by anion-exchange chromatography (mono Q) and gel filtration (Superose 12). The enzyme had an isoelectric point of 4.7 and a molecular weight of 84,000, as estimated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. It was a monomeric protein, the 19-amino-acid N terminus of which displayed 42% homology with the Bacillus subtilis saccharifying alpha-amylase. The amino acid composition of the enzyme showed a high number of acidic and hydrophobic residues and only one cysteine residue per mole. The activity of the alpha-amylase was not stimulated by calcium ions (or other metal ions) or inhibited by EDTA, although the enzyme contained seven calcium atoms per molecule. alpha-Amylase activity on soluble starch was optimal at pH 5.6 and 45 degrees C. The alpha-amylase was stable at an acidic pH but very sensitive to thermal inactivation. It hydrolyzed soluble starch, with a Km of 3.6 g . liter-1 and a Kcat of 122 mol of reducing sugars . s-1 . mol-1. The alpha-amylase showed greater activity with high-molecular-weight substrates than with low-molecular-weight maltooligosaccharides, hydrolyzed glycogen and pullulan slowly, but did not hydrolyze dextran or cyclodextrins. The major end products of maltohexaose degradation were glucose, maltose, and maltotriose; maltotetraose and maltopentaose were formed as intermediate products. Twenty seven percent of the glucoamylase activity generally detected in the culture supernatant of C. acetobutylicum can be attributed to the alpha-amylase.
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Affiliation(s)
- V Paquet
- Département de Génie Biochimique et Alimentaire, Centre National de la Recherche Scientifique Unité Associée 544, Toulouse, France
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98
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Declerck N, Joyet P, Gaillardin C, Masson J. Use of amber suppressors to investigate the thermostability of Bacillus licheniformis alpha-amylase. Amino acid replacements at 6 histidine residues reveal a critical position at His-133. J Biol Chem 1990. [DOI: 10.1016/s0021-9258(18)55421-1] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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99
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Boel E, Brady L, Brzozowski AM, Derewenda Z, Dodson GG, Jensen VJ, Petersen SB, Swift H, Thim L, Woldike HF. Calcium binding in alpha-amylases: an X-ray diffraction study at 2.1-A resolution of two enzymes from Aspergillus. Biochemistry 1990; 29:6244-9. [PMID: 2207069 DOI: 10.1021/bi00478a019] [Citation(s) in RCA: 265] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
X-ray diffraction analysis (at 2.1-A resolution) of an acid alpha-amylase from Aspergillus niger allowed a detailed description of the stereochemistry of the calcium-binding sites. The primary site (which is essential in maintaining proper folding around the active site) contains a tightly bound Ca2+ with an unusually high number of eight ligands (O delta 1 and O delta 2 of Asp175, O delta of Asn121, main-chain carbonyl oxygens of Glu162 and Glu210, and three water molecules). A secondary binding site was identified at the bottom of the substrate binding cleft; it involves the residues presumed to play a catalytic role (Asp206 and Glu230). This explains the inhibitory effect of calcium observed at higher concentrations. Neutral Aspergillus oryzae (TAKA) alpha-amylase was also refined in a new crystal at 2.1-A resolution. The structure of this homologous (over 80%) enzyme and additional kinetic studies support all the structural conclusions regarding both calcium-binding sites.
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Affiliation(s)
- E Boel
- Chemistry Department, University of York, Heslington, U.K
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100
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Bush DS, Sticher L, van Huystee R, Wagner D, Jones RL. The calcium requirement for stability and enzymatic activity of two isoforms of barley aleurone α-amylase. J Biol Chem 1989. [DOI: 10.1016/s0021-9258(19)47314-6] [Citation(s) in RCA: 51] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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