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Hong SC, Park KM, Son YH, Jung HS, Kim K, Choi SJ, Chang PS. AOT/isooctane reverse micelles with a microaqueous core act as protective shells for enhancing the thermal stability of Chromobacterium viscosum lipase. Food Chem 2015; 179:263-9. [DOI: 10.1016/j.foodchem.2015.01.120] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2014] [Revised: 01/06/2015] [Accepted: 01/27/2015] [Indexed: 11/17/2022]
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2
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Chaudhuri A, Basu P, Haldar S, Kombrabail M, Krishnamoorthy G, Rajarathnam K, Chattopadhyay A. Organization and dynamics of the N-terminal domain of chemokine receptor CXCR1 in reverse micelles: effect of graded hydration. J Phys Chem B 2013; 117:1225-33. [PMID: 23311880 DOI: 10.1021/jp3095352] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Water plays a fundamental role in the folding, structure, dynamics, and function of proteins and peptides. The extracellular N-terminal domain of chemokine receptors is crucial in mediating binding affinity, receptor selectivity, and regulating function. The flexible N-terminal domain becomes ordered in membranes and membrane-mimetic assemblies, thereby indicating that the membrane could play an important role in regulating CXC chemokine receptor 1 (CXCR1) function. In view of the role of hydration in lipid-protein interactions in membranes, we explored the organization and dynamics of a 34-mer peptide of the CXCR1 N-terminal domain in reverse micelles by utilizing a combination of fluorescence-based approaches and circular dichroism spectroscopy. Our results show that the secondary structure adopted by the CXCR1 N-domain is critically dependent on hydration. The tryptophan residues of the CXCR1 N-domain experience motional restriction and exhibit red edge excitation shift (REES) upon incorporation in reverse micelles. REES and fluorescence lifetime exhibit reduction with increasing reverse micellar hydration. Time-resolved fluorescence anisotropy measurements reveal the effect of hydration on peptide rotational dynamics. Taken together, these results constitute the first report demonstrating modulation in the organization and dynamics of the N-terminal domain of a chemokine receptor in a membrane-like environment of varying hydration. We envisage that these results are relevant in the context of hydration in the function of G protein-coupled receptors.
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Affiliation(s)
- Arunima Chaudhuri
- Centre for Cellular and Molecular Biology, Council of Scientific and Industrial Research, Uppal Road, Hyderabad 500 007, India
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3
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Synthetic application and activity of cutinase in an aqueous, miniemulsion model system: Hexyl octanoate synthesis. Catal Today 2011. [DOI: 10.1016/j.cattod.2011.05.039] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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4
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Biochemical and structural characterisation of cutinase mutants in the presence of the anionic surfactant AOT. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2008; 1784:1326-34. [DOI: 10.1016/j.bbapap.2008.04.017] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/12/2008] [Revised: 04/08/2008] [Accepted: 04/22/2008] [Indexed: 11/18/2022]
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5
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Probing the microenvironment of sol–gel entrapped cutinase: The role of added zeolite NaY. J Biotechnol 2008; 135:181-9. [DOI: 10.1016/j.jbiotec.2008.03.018] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2007] [Revised: 03/04/2008] [Accepted: 03/19/2008] [Indexed: 11/22/2022]
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6
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Brissos V, Eggert T, Cabral J, Jaeger KE. Improving activity and stability of cutinase towards the anionic detergent AOT by complete saturation mutagenesis. Protein Eng Des Sel 2008; 21:387-93. [DOI: 10.1093/protein/gzn014] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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7
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Biasutti MA, Abuin EB, Silber JJ, Correa NM, Lissi EA. Kinetics of reactions catalyzed by enzymes in solutions of surfactants. Adv Colloid Interface Sci 2008; 136:1-24. [PMID: 17706582 DOI: 10.1016/j.cis.2007.07.001] [Citation(s) in RCA: 141] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2006] [Revised: 06/30/2007] [Accepted: 07/02/2007] [Indexed: 11/20/2022]
Abstract
The effect of surfactants, both in water-in-oil microemulsions (hydrated reverse micelles) and aqueous solutions upon enzymatic processes is reviewed, with special emphasis on the effect of the surfactant upon the kinetic parameters of the process. Differences and similarities between processes taking place in aqueous and organic solvents are highlighted, and the main models currently employed to interpret the results are briefly discussed.
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8
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Buche A, Picorel R. Spectral Changes Induced by Alkaline pH and Specific Chemical Modification of Amino Acid Residues in the Light-Harvesting II Antenna Complex from Ectothiorhodospira sp. Photochem Photobiol 2008. [DOI: 10.1111/j.1751-1097.1999.tb03286.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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9
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Martinho JMG, Santos AM, Fedorov A, Baptista RP, Taipa MA, Cabral JMS. Fluorescence of the Single Tryptophan of Cutinase: Temperature and pH Effect on Protein Conformation and Dynamics¶. Photochem Photobiol 2007. [DOI: 10.1562/0031-8655(2003)0780015fotsto2.0.co2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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10
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Ternström T, Svendsen A, Akke M, Adlercreutz P. Unfolding and inactivation of cutinases by AOT and guanidine hydrochloride. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2005; 1748:74-83. [PMID: 15752695 DOI: 10.1016/j.bbapap.2004.12.014] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/03/2004] [Revised: 12/08/2004] [Accepted: 12/15/2004] [Indexed: 11/17/2022]
Abstract
We present a comparative analysis of the unfolding and inactivation of three cutinases in the presence of guanidine hydrochloride (GdnHCl) and bis(2-ethylhexyl) sodium sulfosuccinate (AOT). Previous investigations have focused on the cutinase from Fusarium solani pisi (FsC). In addition to FsC, the present study includes the cutinase from Humicola insolens (HiC) and a mutant variant of HiC (muHiC) with increased activity and decreased surfactant sensitivity. Equilibrium and time-resolved denaturation by AOT were studied in aqueous solution and reverse micelles, and were compared with GdnHCl denaturation. The far-UV CD and fluorescence denaturation profiles obtained in the aqueous solutions of the two denaturants coincide for all three cutinases, indicating that unfolding is a co-operative two-state process under these conditions. In reverse micelles, the cutinases unfold with mono-exponential rates, again indicating a two-state process. The free energy of denaturation in water was calculated by linear extrapolation of equilibrium data, yielding very similar values for the three cutinases with averages of -11.6 kcal mol(-1) and -2.6 kcal mol(-1) for GdnHCl and AOT, respectively. Hence, the AOT denatured state (D(AOT)) is less destabilised than the GdnHCl denatured state (D(GdnHCl)), relative to the native state in water. Far-UV CD spectroscopy revealed that D(AOT) retains some secondary structure, while D(GdnHCl) is essentially unstructured. Similarly, fluorescence data suggest that D(AOT) is more compact than D(GdnHCl). Activity measurements reveal that both D(AOT) and D(GdnHCl) are practically inactive (catalytic activity <1% of that of the native enzyme). The fluorescence spectrum of D(AOT) in reverse micelles did not differ significantly from that observed in aqueous AOT. NMR studies of D(AOT) in reverse micelles indicated that the structure is characteristic of a molten globule, consistent with the CD and fluorescence data.
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Affiliation(s)
- Tomas Ternström
- Department of Biochemistry, Lund University, P.O. Box 124, SE-221 00 Lund, Sweden
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11
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Martinho JMG, Santos AM, Fedorov A, Baptista RP, Taipa MA, Cabral JMS. Fluorescence of the single tryptophan of cutinase: temperature and pH effect on protein conformation and dynamics. Photochem Photobiol 2003; 78:15-22. [PMID: 12929743 DOI: 10.1562/0031-8655(2003)078<0015:fotsto>2.0.co;2] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The cutinase from Fusarium solani pisi is an enzyme with a single L-tryptophan (Trp) involved in a hydrogen bond with an alanine (Ala) residue and located close to a cystine formed by a disulfide bridge between two cysteine (Cys) residues. The Cys strongly quenches the fluorescence of Trp by both static and dynamic quenching mechanisms. The Trp fluorescence intensity increases by about fourfold on protein melting because of the disruption of the Ala-Trp hydrogen bond that releases the Trp from the vicinity of the cystine residue. The Trp forms charge-transfer complexes with the disulfide bridge, which is disrupted by UV light irradiation of the protein. This results in a 10-fold increase of the Trp fluorescence quantum yield because of the suppression of the static quenching by the cystine residue. The Trp fluorescence anisotropy decays are similar to those in other proteins and were interpreted in terms of the wobbling-in-cone model. The long relaxation time is attributed to the Brownian rotational correlation time of the protein as a whole below the protein-melting temperature and to protein-backbone dynamics above it. The short relaxation time is related to the local motion of the Trp, whose mobility increases on protein denaturation.
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Affiliation(s)
- J M G Martinho
- Centro de Química-Física Molecular, Instituto Superior Técnico, Lisbon, Portugal.
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12
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Melo EP, Baptista RP, Cabral JM. Improving cutinase stability in aqueous solution and in reverse micelles by media engineering. ACTA ACUST UNITED AC 2003. [DOI: 10.1016/s1381-1177(03)00044-4] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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13
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Melo EP, Costa SMB, Cabral JMS, Fojan P, Petersen SB. Cutinase-AOT interactions in reverse micelles: the effect of 1-hexanol. Chem Phys Lipids 2003; 124:37-47. [PMID: 12787942 DOI: 10.1016/s0009-3084(03)00031-8] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Cutinase encapsulated in dioctyl sulfosuccinate reverse micelles displays very low stability, undergoing fast denaturation due to an anchoring at the micellar interface. The denaturation process and the structure of the reverse micelle were characterized using biophysical techniques. The kinetics of denaturation observed from fluorescence match the increase of the hydrodynamic radius of reverse micelles. Denaturation in reverse micelles is mainly the unfolding of the three-dimensional structure since the decrease in the circular dichroism ellipticity in the far-UV range is very small. The process is accompanied by an increase in the steady-state anisotropy, as opposed to what happens for denaturation in aqueous solution. Since 1-hexanol used as co-surfactant in dioctyl sulfosuccinate reverse micelles slows or even prevents cutinase denaturation, its effect on cutinase conformation and on the size of reverse micelles was analyzed. When 1-hexanol is present, cutinase is encapsulated in a large reverse micelle, as deduced from dynamic light scattering. The large reverse micelle filled with cutinase was built from the fusion of reverse micelles according to a pseudo-unimolecular process ranging in time from a few minutes to 2h depending on the reverse micellar concentration. This slow equilibrium driven by the encapsulated cutinase has not been reported previously. The encapsulation of cutinase in dioctyl sulfosuccinate reverse micelles establishes a completely new equilibrium characterized by a bimodal population of empty and filled reverse micelles, whose characteristics depend greatly on the interfacial characteristics, that is, on the absence or presence of 1-hexanol.
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Affiliation(s)
- Eduardo P Melo
- Faculdade de Engenharia dos Recursos Naturais, Universidade do Algarve, Campus de Gambelas, 8000-117 Faro, Portugal.
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14
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Yi Y, Kermasha S, L’Hocine L, Neufeld R. Encapsulation of chlorophyllase in hydrophobically modified hydrogel. ACTA ACUST UNITED AC 2002. [DOI: 10.1016/s1381-1177(02)00182-0] [Citation(s) in RCA: 10] [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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15
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Melo EP, Aires-Barros MR, Cabral JM. Reverse micelles and protein biotechnology. BIOTECHNOLOGY ANNUAL REVIEW 2002; 7:87-129. [PMID: 11686050 DOI: 10.1016/s1387-2656(01)07034-x] [Citation(s) in RCA: 87] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Reverse micelles are nanometer-sized (1-10 nm) water droplets dispersed in organic media obtained by the action of surfactants. Surfactant molecules organize with the polar part to the inner side able to solubilize water and the apolar part in contact with the organic solvent. Proteins can be solubilized in the water pool of reverse micelles. Studies on the structure-function relationships of proteins in reverse micelles are very important since the microenvironment in which the protein is solubilized has physico-chemical properties distinct from a bulk aqueous solution. Some of the unique characteristics of reverse micelles make them very useful for biotechnological applications. Charge and hydrophilic/hydrophobic characteristics of the protein and the selection of surfactant can be used to achieve selective solubilization of proteins. This has been used to extend the classical liquid-liquid extraction with solvents to protein bioseparation. For biocatalysis the presence of a bulk organic solvent allow synthetic reactions to be performed via the control of water content and the solubilization of hydrophobic substrates. This is accomplished with a higher interfacial area (about 100 m2/mL) than the conventional biphasic systems, minimizing mass transfer problems.
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Affiliation(s)
- E P Melo
- Universidade do Algarve-F.E.R.N., Campus de Gambelas, 8000 Faro, Portugal.
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16
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Li L, Song A, Xie Y, Huang Z, de Waal E, Urszula K, Canters GW. Expression, purification and characterization of the soluble CuA domain of cytochrome c oxidase ofParacoccus versutus. CHINESE SCIENCE BULLETIN-CHINESE 2001. [DOI: 10.1007/bf02900617] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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17
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Fernandes S, Johansson G, Hatti-Kaul R. Purification of recombinant cutinase by extraction in an aqueous two-phase system facilitated by a fatty acid substrate. Biotechnol Bioeng 2001; 73:465-75. [PMID: 11344451 DOI: 10.1002/bit.1081] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Purification of recombinant wild-type cutinase from the culture supernatant of Saccharomyces cerevisiae by extraction in aqueous two-phase system was investigated. The partition of the enzyme in a polyethylene glycol (PEG)-potassium phosphate system to the top phase was increased with lower molecular weight PEG. Enzyme partition in a 20% PEG/15% phosphate two-phase system was studied in the presence of detergents, fatty acids, and alcohols, respectively. Addition of 0.5% (w/w) butyrate increased the partition coefficient from 17 to 135 and the purification factor from 10 to 23. The effect of butyrate was also confirmed by using the countercurrent mode of extraction. Recovery of cutinase from the top phase was achieved by a secondary extraction into a new salt phase at a lower pH or a lower temperature. A specific interaction of butyrate to the active site of the enzyme was demonstrated by fluorescence spectroscopy. Size exclusion chromatography showed the cutinase-butyrate complex to be over two times the size of the free enzyme.
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Affiliation(s)
- S Fernandes
- Department of Biotechnology, Center for Chemistry and Chemical Engineering, Lund University, P.O. Box 124, S-221 00 Lund, Sweden
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18
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19
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Bhattacharya D, Basu S, Mandal PC. UV radiation effects on flavocytochrome b2 in dilute aqueous solution. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY. B, BIOLOGY 2000; 59:54-63. [PMID: 11332891 DOI: 10.1016/s1011-1344(00)00137-8] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
A dilute aqueous solution of flavocytochrome b2 when exposed to inactivating doses of UV radiation at 280 nm underwent reversible loss in activity both under aerated and deaerated conditions. The active site as well as the substrate binding sites were found to be modified in the irradiated enzyme. Irradiation of the enzyme in the UV-C range resulted in partial unfolding of the polypeptide framework. Destruction and/or modification of both tryptophan and tyrosine residues as well as heme moieties took place. Preliminary laser flash photolysis studies suggest that the initial photo-ionization takes place with tryptophan and tyrosine residues with the formation of excited states and radicals, and then rapid transfer of electrons takes place to histidyl and cystinyl sites which might have eventually been altered in the process.
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Affiliation(s)
- D Bhattacharya
- Chemical Sciences Division, Saha Institute of Nuclear Physics, Calcutta, India
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20
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Melo EP, Taipa MA, Castellar MR, Costa SM, Cabral JM. A spectroscopic analysis of thermal stability of the Chromobacterium viscosum lipase. Biophys Chem 2000; 87:111-20. [PMID: 11099174 DOI: 10.1016/s0301-4622(00)00171-x] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The thermal stability of the lipase from Chromobacterium viscosum was assessed by deactivation (loss of activity), fluorescence, circular dichroism (CD) and static light scattering (SLS) measurements. Lipase fluorescence emission is dominated by the tryptophyl contribution. An increase in the tyrosyl contribution from 2 to 16% was only observed upon prolonged incubation at 60 degrees C. The effect of temperature on the tryptophyl quantum yield was studied and two activation energies were calculated. Tryptophan residues in the native structure have an activation energy of 1.9 kcal mol(-1) for temperature-dependent non-radiative deactivation of the excited state. A structural change occurs at approximately 66.7 degrees C and the activation energy increases to 10.2 kcal mol(-1). This structural change is not characterized by tryptophan exposure on the surface of the protein. The deactivation and the evolution of structural changes with time after lipase incubation at 60 degrees C were assessed by fluorescence, CD and SLS measurements. CD spectra show that both secondary and tertiary structures remain native-like after incubation at 60 degrees C in spite of the fluorescence changes observed (red-shift from 330 to 336 nm on the trytophyl emission). SLS measurements together with the CD data show that deactivation may be due to protein association between native molecules. Deactivation and the decrease on the fraction of non-associated native lipase evaluated by changes in fluorescence intensity with time, show apparent first order kinetics. According to the rate constants, fluorescence changes precede deactivation pointing to an underestimation of the deactivation. Reactivation upon dilution during the activity assay and substrate-induced reactivation due to lipase interfacial adsorption are possible causes for this underestimation.
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Affiliation(s)
- E P Melo
- Unidade de Ciências e Tecnologias Agrárias, Universidade do Algarve, Faro, Portugal.
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21
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Melo EP, Fojan P, Cabral JM, Petersen SB. Dynamic light scattering of cutinase in AOT reverse micelles. Chem Phys Lipids 2000; 106:181-9. [PMID: 10930568 DOI: 10.1016/s0009-3084(00)00152-3] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
The fungal lipolytic enzyme cutinase, incorporated into sodium bis-(2ethylhexyl) sulfosuccinate reversed micelles has been investigated using dynamic light scattering. The reversed micelles form spontaneously when water is added to a solution of sodium bis-(2ethylhexyl) sulfosuccinate in isooctane. When an enzyme is previously dissolved in the water before its addition to the organic phase, the enzyme will be incorporated into the micelles. Enzyme encapsulation in reversed micelles can be advantageous namely to the conversion of water insoluble substrates and to carry out synthesis reactions. However protein unfolding occurs in several systems as for cutinase in sodium bis-(2ethylhexyl) sulfosuccinate reversed micelles. Dynamic light scattering measurements of sodium bis-(2ethylhexyl) sulfosuccinate reversed micelles with and without cutinase were taken at different water to surfactant ratios. The results indicate that cutinase was attached to the micellar wall and that might cause cutinase unfolding. The interactions between cutinase and the bis-(2ethylhexyl) sulfosuccinate interface are probably the driving force for cutinase unfolding at room temperature. Twenty-four hours after encapsulation, when cutinase is unfolded, a bimodal distribution was clearly observed. The radii of reversed micelles with unfolded cutinase were determined and found to be considerable larger than the radii of the empty reversed micelles. The majority of the reversed micelles were empty (90-96% of mass) and the remainder (4-10%) containing unfolded cutinase were larger by 26-89 A.
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Affiliation(s)
- E P Melo
- Unidade de Ciências e Tecnologias Agrárias, Universidade do Algarve, Campus de Gambelas, 8000, Faro, Portugal.
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22
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Bhattacharya D, Saha A, Mandal P. Radiation induced modification of tryptophan and tyrosine residues in flavocytochrome b2 in dilute aqueous solution. Radiat Phys Chem Oxf Engl 1993 2000. [DOI: 10.1016/s0969-806x(99)00520-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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23
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Abstract
This review analyzes the role of cutinases in nature and their potential biotechnological applications. The cloning and expression of a fungal cutinase, Fusarium solani f. pisi, in Escherichia coli and Saccharomyces cerevisiae hosts are described. The three-dimensional structure of this cutinase is also analyzed and its function as a lipase is discussed and compared with other lipases. The biocatalytic applications of cutinase are described taking into account the preparation of different cutinase forms and the media in which the different types of reactions have been performed, namely hydrolysis, esterification, transesterification, and resolution of racemic mixtures. The stability of cutinase preparations is discussed and, in particular, the cutinase stability in anionic reversed micelles is analyzed considering the role of hexanol as a substrate, a cosurfactant, and a stabilizer. Process development, based on the operation of cutinase reactors, is also reviewed.
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Affiliation(s)
- C M Carvalho
- Centro de Engenharia Biológica e Química, Instituto Superior Técnico, 1049-001 Lisboa, Portugal
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24
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Bhattacharya D, Basu S, Mandal PC. Visible radiation effects on flavocytochrome b2 in dilute aqueous solution: a steady-state and laser flash photolysis study. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY. B, BIOLOGY 1998; 47:173-80. [PMID: 10093916 DOI: 10.1016/s1011-1344(98)00218-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Irradiation of flavocytochrome b2 by visible radiation at 450 nm in dilute aqueous solution is found to have a devastating effect not only on its activity but also on the important flavin mononucleotide (FMN) constituents. The active site and the substrate binding site are also found to be largely modified on exposure to visible radiation. This has a telling effect on the constituent aromatic amino acids, tryptophan and tyrosine, and therefore justifies the role of FMN as a very potent photosensitizer. Partial unfolding of the irradiated enzyme molecule is also observed. Damage is much greater in deaerated conditions, which indicates that molecular oxygen plays a protecting role in this particular system. The inactivation is mediated through rapid electron transfer from tryptophan and tyrosine to excited flavin, forming flavin semiquinone and tryptophanyl and tyrosinyl radicals, which in turn cause permanent damage at the molecular level.
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Affiliation(s)
- D Bhattacharya
- Nuclear Chemistry Division, Saha Institute of Nuclear Physics, Calcutta, India
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25
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Melo EP, Carvalho CM, Aires-Barros MR, Costa SM, Cabral JM. Deactivation and conformational changes of cutinase in reverse micelles. Biotechnol Bioeng 1998; 58:380-6. [PMID: 10099272 DOI: 10.1002/(sici)1097-0290(19980520)58:4<380::aid-bit5>3.0.co;2-f] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Deactivation data and fluorescence intensity changes were used to probe functional and structural stability of cutinase in reverse micelles. A fast deactivation of cutinase in anionic (AOT) reverse micelles occurs due to a reversible denaturation process. The deactivation and denaturation of cutinase is slower in small cationic (CTAB/1-hexanol) reverse micelles and does not occur when the size of the cationic reverse micellar water-pool is larger than cutinase. In both systems, activity loss and denaturation are coupled processes showing the same trend with time. Denaturation is probably caused by the interaction between the enzyme and the surfactant interface of the reversed micelle. When the size of the empty reversed micelle water-pool is smaller than cutinase (at W0 5, with W0 being the water:surfactant concentration ratio) a three-state model describes denaturation and deactivation with an intermediate conformational state existing on the path from native to denaturated cutinase. This intermediate was clearly detected by an increase in activity and shows only minor conformational changes relative to the native state. At W0 20, the size of the empty water-pool was larger than cutinase and the data was well described by a two-state model for both anionic and cationic reverse micelles. For AOT reverse micelles at W0 20, the intermediate state became a transient state and the deactivation and denaturation were described by a two-state model in which only native and denaturated cutinase were present. For CTAB/1-hexanol reverse micelles at W0 20, the native cutinase was in equilibrium with an intermediate state, which did not suffer denaturation. 1-Hexanol showed a stabilizing effect on cutinase in reverse micelles, contributing to the higher stabilities observed in the cationic CTAB/1-hexanol reverse micelles. Copyright 1998 John Wiley & Sons, Inc.
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Affiliation(s)
- EP Melo
- Centro de Engenharia Biologica e Quimica, Laboratorio Engenharia Bioquimica, Instituto Superior Tecnico, 1000 Lisbon, Portugal
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26
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Cabral JM, Aires-Barros MR, Pinheiro H, Prazeres DM. Biotransformation in organic media by enzymes and whole cells. J Biotechnol 1997; 59:133-43. [PMID: 9487721 DOI: 10.1016/s0168-1656(97)00176-4] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Biotransformation of poorly water soluble compounds in organic media by immobilized enzyme and whole cells is illustrated in this paper taking the following examples from the author's laboratory: (1) controlled hydrolysis of triglycerides and synthesis reactions by a recombinant lipolytic enzyme (cutinase); (2) enzymatic synthesis of dipeptides; (3) continuous production of isovaleraldehyde by Gluconobacter oxydans in isooctane; and (4) sitosterol side chain cleavage by Mycobacterium sp. The role of water and organic solvent are evaluated, namely the increase in the volumetric productivity of the reaction system and the shift of the reaction equilibrium in favour of product synthesis. High product yields have been obtained due to the reduction of substrate/product inhibition. Biocatalyst stability in the presence of the organic phase was also performed.
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Affiliation(s)
- J M Cabral
- Laboratório de Engenharia Bioquímica, Instituto Superior Técnico, Lisboa, Portugal
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Carvalho C, Serralheiro M, Cabral J, Aires-Barros M. Application of factorial design to the study of transesterification reactions using cutinase in AOT-reversed micelles. Enzyme Microb Technol 1997. [DOI: 10.1016/s0141-0229(96)00245-1] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Continuous extraction of a recombinant cutinase from Escherichia coli disrupted cells with reversed micelles using a perforated rotating disc contactor. ACTA ACUST UNITED AC 1996. [DOI: 10.1007/bf02391586] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Pinto-Sousa AM, Cabral JMS, Aires-Barros MR. Stability of a Fusarium solani pisi recombinant cutinase in phosphatidylcholine reversed micelles. Biotechnol Lett 1996. [DOI: 10.1007/bf00140207] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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