The comparative biochemistry, physiology, and genetics of animal alpha-amylases

Preparation of p-aminophenol modified superparamagnetic iron oxide nanoparticles for purification of α-amylase from the bovine milk

Currently, modified Fe₃O₄ magnetic nanoparticles frequently are used as nanocarriers for proteins and enzymes purification. In the present study, Fe₃O₄ magnetic nanoparticles were prepared, and their surfaces were modified with p-aminophenol affinity ligand immobilized by different linkers. The modified nanocarriers were used for the purification of α-amylase from the bovine milk (after precipitation the casein) by affinity purification. To evaluate the effectiveness of the p-aminophenol modified magnetic nanocarriers, the three different types of nanocarriers with different linkers having varying lengths were prepared. All nanocarriers were characterized and validated using FT-IR, SEM, EDX, VSM and XRD analysis methods According to our results, p-aminophenol ligand attached to the nanocarrier by long linkers better separates the α-amylase from the casein free skim milk with 49.66% recovery and 48.18-fold purification efficiency. The results of this study showed that our novel magnetic nanocarriers have the capacity to be used for fast, reproducible and cost-effective purification of α-amylase.

Purification and high-resolution top-down mass spectrometric characterization of human salivary α-amylase

Human salivary α-amylase (HSAMY) is a major component of salivary secretions, possessing multiple important biological functions. Here we have established three methods to purify HSAMY in human saliva for comprehensive characterization of HSAMY by high-resolution top-down mass spectrometry (MS). Among the three purification methods, the affinity method based on the enzyme-substrate specific interaction between amylase and glycogen is preferred, providing the highest purity HSAMY with high reproducibility. Subsequently, we employed Fourier transform ion cyclotron resonance MS to analyze the purified HSAMY. The predominant form of α-amylase purified from saliva of various races and genders is nonglycosylated with the same molecular weight of 55,881.2, which is 1885.8 lower than the calculated value based on the DNA-predicted sequence. High-resolution MS revealed the truncation of the first 15 N-terminal amino acids (-1858.96) and the subsequent formation of pyroglutamic acid at the new N-terminus Gln (-17.03). More importantly, five disulfide bonds in HSAMY were identified (-10.08) and effectively localized by tandem MS in conjunction with complete and partial reduction by tris (2-carboxyethyl) phosphine. Overall, this study demonstrates that top-down MS combined with affinity purification and partial reduction is a powerful method for rapid purification and complete characterization of large proteins with complex and overlapping disulfide bond patterns.

Where do animal α-amylases come from? An interkingdom trip

Alpha-amylases are widely found in eukaryotes and prokaryotes. Few amino acids are conserved among these organisms, but at an intra-kingdom level, conserved protein domains exist. In animals, numerous conserved stretches are considered as typical of animal alpha-amylases. Searching databases, we found no animal-type alpha-amylases outside the Bilateria. Instead, we found in the sponge Reniera sp. and in the sea anemone Nematostella vectensis, alpha-amylases whose most similar cognate was that of the amoeba Dictyostelium discoideum. We found that this "Dictyo-type" alpha-amylase was shared not only by these non-Bilaterian animals, but also by other Amoebozoa, Choanoflagellates, and Fungi. This suggested that the Dictyo-type alpha-amylase was present in the last common ancestor of Unikonts. The additional presence of the Dictyo-type in some Ciliates and Excavates, suggests that horizontal gene transfers may have occurred among Eukaryotes. We have also detected putative interkingdom transfers of amylase genes, which obscured the historical reconstitution. Several alternative scenarii are discussed.

Human pancreatic digestive enzymes

A primary function of the pancreas is to produce digestive enzymes that are delivered to the small intestine for the hydrolysis of complex nutrients. Much of our understanding of digestive enzymes comes from studies in animals. New technologies and the availability of the sequence of the human genome allow for a critical review of older reports and assumptions based on animal studies. This report updates our understanding of human pancreatic digestive enzymes with a focus on new insights into the biology of human proteases, lipases and amylases.

?-Amylase Kinetic Test in Bodily Single and Mixed Stains

Recently, in Italy, a murder and a putative sexual violence was accomplished on a child. A bodily fluids mixture on the child's underwear between the victim (female) and the suspect (male) was ascertained by short tandem repeat (STR) DNA typing and, due to the absence of seminal fluid, saliva from the suspect and urine from the child was hypothesized. In order to investigate the possibility of specifically and rapidly detecting saliva stains both alone and mixed with other bodily fluids, we used a quantitative spectrophotometric technique, named Amylase test, for the detection of alpha-amylases. We determined alpha-amylase activity and reaction kinetic curves in several samples collected from the child's underwear. In order to confirm our intuition, we first tested saliva, perspiration, and urine, singularly and in mixtures; second, several forensic stains including saliva, perspiration, urine stains, saliva/perspiration, and saliva/urine mixture stains were tested. Evaluating alpha-amylase activity values and time-course curves' behavior of alpha-amylase reactions we were able to recognize successfully, in all cases, the presence of saliva and to distinguish it specifically from other bodily fluids containing alpha-amylase. A further confirmation of our result was provided by STR DNA typing on several areas of the underwear: a clear correlation between alpha-amylases activity and male DNA was detected on all the samples evaluated.

Identification of Glutamate Residues Important for Catalytic Activity or Thermostability of a Truncated Bacillus sp. Strain TS-23 α-amylase by Site-directed Mutagenesis

The importance of 17 glutamate residues of a truncated Bacillus sp. strain TS-23 alpha-amylase (BACdeltaNC) was investigated by site-directed mutagenesis. The Ala- and Asp-substituted variants were overexpressed in the recombinant E. coli cells and the 54-kDa proteins were purified to nearly homologous by nickel-chelate chromatography. Glu-295, which locates in the conserved region III of amylolytic enzymes, mutations resulted in a complete loss of enzyme activity. The specific activity for E151A was decreased by more than 30%, while other variants showed activity comparable to that of BACdeltaNC. A decreased half-life at 70 degrees C was observed for Glu-219 variants with respective to the wild-type enzyme, suggesting that replacement of Glu-219 by either Ala or Asp might have a significant destabilizing effect on the protein structure.

Expression, characterization, and biochemical properties of recombinant human salivary amylase

Human salivary amylase, a major component of human salivary secretions, possesses multiple functions in the oral cavity. It is the only enzyme in saliva capable of degrading oligosaccharides, which are used by the oral microflora for nutritional purposes. In order to understand its role in disease processes such as caries, we have undertaken the structure-function analyses of amylase. In this regard, the nonglycosylated human salivary amylase was expressed in a baculovirus expression system. The native and the recombinant amylases exhibit similar biochemical as well as biophysical properties. Unlike recombinant human pancreatic amylase, recombinant human salivary amylase is not glycosylated when expressed in a baculovirus system as determined from the crystal structure determination of the recombinant enzyme. Therefore, this system is suitable for further structure-function work without resorting to enzymatic removal of the carbohydrate chain. Details of the expression, purification, and biophysical properties will be presented.

Oral colonization and cariogenicity of Streptococcus gordonii in specific pathogen-free TAN:SPFOM(OM)BR rats consuming starch or sucrose diets

The significance of Streptococcus gordonii in dental caries is undefined, as is that of other alpha-amylase-binding bacteria (ABB) commonly found in the mouth. To clarify the ecological and cariological roles of S. gordonii our specific pathogen-free Osborne-Mendel rats, TAN:SPFOM(OM)BR, were fed either diet 2000 (containing 56% confectioner's sugar, most of which is sucrose) or diet 2000CS (containing 56% cornstarch, in lieu of confectioner's sugar) and inoculated with S. gordonii strains. Uninoculated rats were free of both indigenous mutans streptococci (MS) and ABB, including S. gordonii, as shown by culture on mitis salivarius and blood agars of swabs and sonicates of dentitions after weanlings had consumed these diets for 26 days. ABB were detected by radiochemical assay using [125I]-amylase reactive to alpha-amylase-binding protein characteristic of the surface of S. gordonii and other ABB. No ABB were detected (detection limit < 1 colony-forming units in 10(6) colony-forming units). Thus the TAN:SPFOM(OM)BR colony presents a 'clean animal model' for subsequent study. Consequently, S. gordonii strains Challis or G9B were used to inoculate weanling rat groups consuming either the high-sucrose diet 2000 or the cornstarch diet 2000CS. Two additional groups fed each of these diets remained unioculated. Recoveries of inoculants were tested 12 and 26 days later by oral swabs and sonication of the molars of one hemimandible of each animal, respectively. Uninoculated animals were reconfirmed to be free of ABB and mutans streptococci, but inoculated ones eating diet 2000CS had S. gordonii recoveries of 1-10% or, if eating diet 2000, 10-30% of total colony-farming units in sonicates. There were no statistically significant differences among the inoculated and uninoculated animal groups' caries scores when they ate the cornstarch diet. Lesion scores for sucrose-eating rats were, however, from 2.4-5.1-fold higher than for cornstarch-eating rats, P < 0.001, and were still higher if animals had been inoculated with either Challis (1.41-fold) or G9B (1.64-fold), than if uninoculated, both P < 0.001, so long as the rats ate the sucrose diet. Therefore, TAN:SPFOM(OM)BR rats do not harbour ABB or S. gordonii but can be colonized by S. gordonii. Colonization levels of S. gordonii on the teeth are higher in the presence of high sucrose than with high starch-containing diets. Caries scores are augmented by sucrose compared with starch, and are further augmented by S gordonii colonization. S. gordonii is thus cariologically significant in the presence of sucrose, at least in this rat.

Changes of salivary amylase in serum and parotid gland during pharmacological and physiological stimulation

Although serum amylase level is an important diagnostic factor in certain salivary and pancreatic diseases, little information is available regarding the mechanism by which parotid amylase reaches the circulatory system. The present study was carried out to investigate the relationship between parotid isoamylase concentrations in blood serum and in parotid tissue in response to various stimuli. Wistar rats were fed with standard laboratory rodent chow; water was supplied ad libitum. In the first experiment, after a 16-h fasting, rats received either 5 mg/kg pilocarpine or saline (control). In the second study, after fasting, half of the rats were fed for 1 h, the other half received no food. In the third experiment, the changes in serum and tissue enzyme levels were monitored in freely fed animals during the peak-food intake phase, the first 2 h of the dark period. Amylase concentration was determined by using starch as a substrate. Pancreatic and parotid isoamylase levels in serum were separated by gel-electrophoresis utilizing differences in ionic properties of the isoenzymes. As expected, pilocarpine strongly stimulated tissue amylase discharge and serum amylase elevation. Similar, but less pronounced changes were observed not only during refeeding of fasted animals, but also in nonfasted rats during their peak-feeding period. Our data suggest that pharmacological stimulation, such as with pilocarpine or feeding in fasted state, as well as a mild stimulation of parotid function by spontaneous food intake during nonfasted state results in a decrease in parotid tissue amylase activity and a proportional increase in serum levels of parotid isoamylase.

Purification and characterization of two alpha-amylases from Toxoplasma gondii

Two distinct alpha-amylases have been identified in Toxoplasma gondii. They were purified close to homogeneity from cytoplasmic and membrane fractions. The apparent molecular weight of the cytoplasmic amylase was 22,300 Da and that of the membrane enzyme was 39,600 Da by gel filtration, and 25,000 and 41,000 Da by SDS gel electrophoresis, respectively. The physicochemical and catalytic properties of both enzymes showed them to be very different. Cytoplasmic alpha-amylase had an acid isoelectric point and its optimum pH was pH 5.0; its activity was unaffected by NaCl, Ca2+, or EDTA. The membrane alpha-amylase had an isoelectric point of 7.7 and an optimum pH of 8.0. It was affected by Ca2+, inhibited by EDTA, and activated eight-fold by NaCl. Both amylases were inactivated by temperatures above 65 degrees C, but cytoplasmic amylase was more resistant to thermal denaturation.

The roles of histidine residues at the starch-binding site in streptococcal-binding activities of human salivary amylase

Human salivary alpha-amylase participates in the initial digestion of starch and may be involved in the colonization of viridans streptococci in the mouth. To elucidate the role of histidine residues located near the starch-binding site on the streptococcal-binding activity, the wild type and three histidine mutants, H52A, H299A and H305A were constructed and expressed in a baculovirus system. While His52 is located near the non-reducing end of the starch-binding pocket (subsite S3/S4), the residues His299 and His305 are located near the subsites S1/S1'. For the wild type, the cDNA encoding the leader and secreted sequences of human salivary amylase was amplified by polymerase chain reaction from a human submandibular salivary-gland cDNA library, and subcloned into the baculovirus shuttle vector pVL1392 downstream of the polyhedrin promoter. Oligonucleotide-based, site-directed mutagenesis was used to generate the mutants expressed in the baculovirus system. Replacing His52 or His299 or His305 to Ala residue did not alter the bacterial-binding activity significantly, but these mutants did show differences in their catalytic activities. The mutant H52A showed negligible reduction in enzymatic activity compared to that of wild type for the hydrolysis of starch and oligosaccharides. In contrast, the H299A and H305A mutants showed a 12 to 13-fold reduction (90-92%) in starch-hydrolysing activity. In addition, the k(cat) for the hydrolysis of oligosaccharides by H299A decreased by as much as 11-fold for maltoheptaoside. This reduction was even higher (40-fold) for the hydrolysis of p-nitrophenyl maltoside, with a significant change in K(M). The mutant H305A, however, exhibited a reduction in k(cat) only, with no changes in the K(M) for the hydrolysis of oligosaccharides. The reduction in the k(cat) for the H305A mutant was almost 93% for maltoheptaoside hydrolysis. The pH activity profile for the H305A mutant was also significantly different from that of the wild type and the other two mutants. These results suggest that, although histidines at the starch-binding site of salivary amylase are involved in starch binding and catalysis, they may not participate in Streptococcus gordonii G9B binding.

Metabolic evolution in alpha-amylases from Drosophila virilis and D. repleta, two species with different ecological niches

alpha-Amylases from Drosophila virilis and D. repleta were partially purified by ion exchange chromatography. The two amylases share common characteristics for pH and cations effects, although with slight differences. D. virilis has optimal activity at pH 6.6 and D. repleta at pH 7.2. Calcium, sodium, and potassium cations activate amylolytic activity in both species but Ba2+ has an activation effect in D. repleta only. In contrast, there are major differences in thermal offbility and kinetics among amylases of the two species. D. virilis amylase is much more stable at high temperature and the optimal temperatures are very different between the two species, respectively, 45 degrees C and 30 degrees C for D. virilis and D. repleta. alpha-Amylase activity using different substrates is greater on starch than on glycogen in both species and still higher on amylose for D. virilis, the nonfungus feeder species. alpha-Amylase of D. repleta, the mycophagous species, has a better affinity to amylopectin and glycogen. Such differences in substrate specificity suggest adaptation to different resources in these species living in different habitats. Metabolic evolution seems to have occurred through a "tradeoff" between kinetic effectiveness and the nature of substrate, with a higher Vmax on amylose for D. virilis and a lower K(m) on glycogen for D. repleta.

Interactions of streptococcal glucosyltransferases with alpha-amylase and starch on the surface of saliva-coated hydroxyapatite

The salivary pellicle consists of various proteins and glycoproteins which may interact with one another. Experiments were performed to elucidate the interactions of streptococcal glucosyltransferase (Gtf) enzymes with human salivary alpha-amylase in solution and on the surface of saliva-coated hydroxyapatite (SHA) beads. The Gtf enzymes -B, -C and -D, when immobilized on to SHA beads, reduced the activity of adsorbed amylase; GtfD showed the highest inhibition of salivary amylase activity. The presence of glucan produced by immobilized GtfD did not further reduce amylase activity. The amount of amylase adsorbed on to hydroxyapatite beads was reduced when salivary amylase was added simultaneously with any of the Gtf enzymes, suggesting that amylase and Gtfs may compete with each other for binding sites on hydroxyapatite. Starch hydrolysates produced by SHA-surface-bound salivary amylase were tested for their effect on glucan production from sucrose by Gtf enzymes in solution and on SHA beads; glucan production by SHA-immobilized GtfB was stimulated in the presence of starch hydrolysates. Glucan synthesized by SHA-immobilized GtfB in the presence of starch hydrolysates was less susceptible to hydrolysis by the fungal enzyme mutanase than was glucan made by SHA-immobilized GtfB in the absence of starch hydrolysates. Glucan production by GtfB associated with streptococci immobilized on to SHA was also enhanced in the presence of starch hydrolysates. The adhesion of oral micro-organisms to SHA coated with glucan made in the presence and absence of starch hydrolysates was investigated, and some bacteria displayed higher adhesion activities for the glucan made in the presence of the hydrolysates. Therefore, the interaction of amylase and Gtf enzymes on a SHA surface may modulate the formation of glucan and the adherence of oral micro-organisms.

Biochemical composition of human saliva in relation to other mucosal fluids

This paper describes several salivary components and their distribution in other mucosal secretions. Histatins are polypeptides which possess exceptional anti-fungal and anti-bacterial activities, but are nevertheless present only in saliva. Proline-rich proteins (PRPs) are members of a closely related family, of which the acidic PRPs are found solely in saliva, whereas the basic PRPs are also found in other secretions. Mucins are a group of glycoproteins that contribute to the visco-elastic character of the mucosal secretions. Despite the similarities in their structure and behavior, mucins have distinct tissue distributions and amino acid sequences. Other salivary proteins are present in one or more mucosal secretions. Lysozyme is an example of a component belonging to an ancient self-defense system, whereas secretory immunoglobulin A (sIgA) is the secreted part of a sophisticated adaptive immune system. Cystatins are closely related proteins which belong to a multigene family. Alpha-Amylase is a component that is believed to play a specific role in digestion, but is nevertheless present in several body fluids. Kallikrein and albumin are components of blood plasma. But whereas albumin diffuses into the different mucosal secretions, kallikrein is secreted specifically by the mucosal glands. The presence of these proteins specifically in saliva, or their distribution in other mucosal secretions as well, may provide important clues with respect to the physiology of those proteins in the oral cavity.

Emergence in human dental plaque and host distribution of amylase-binding streptococci

Salivary amylase is known to bind specifically to several species of oral streptococci. To assess the importance of this interaction in bacterial colonization of the oral cavity, we determined the proportion and identity of amylase-binding bacteria (ABB) in dental plaque of humans and various salivary amylase-secreting and non-secreting mammalian species. The numbers of ABB in undisturbed plaque collected over time from tooth surfaces of six human volunteers or from 14 other mammalian species were determined by means of a replicating assay. The mean proportion of ABB cultured aerobically from human teeth at 2 h was 10.5% (SD 10), at 8 h 7.9% (8), at 24 h 13% (11), and at 48 h 12% (9). The mean proportion of anaerobically cultured ABB found at 2 h was 3% (SD 4), at 8 h 5% (5), at 24 h 12% (9), and at 48 h 16% (12). Amylase-binding bacteria cultured from these samples resembled Streptococcus mitis, Streptococcus gordonii, Streptococcus salivarius, Streptococcus crista, or unidentified streptococci. In addition, only animals exhibiting salivary amylase activity in their saliva harbored ABB (ranging from 2 to 31% of the total flora), with the exception of the pig, where no ABB were found to colonize, despite considerable amylase activity in saliva. Only strains resembling S. mitis and S. salivarius and unspeciated strains were isolated from these mammals. These results suggest that amylase-binding streptococci are the predominant ABB in human plaque, and their numbers generally increase as plaque develops. Since ABB colonized only the oral cavities of hosts demonstrating salivary amylase activity, the ability to bind amylase may play an important role in oral colonization by these bacteria.

Isolation of the murine ribonuclease gene Rib-1: structure and tissue specific expression in pancreas and parotid gland

The mouse pancreatic ribonuclease gene Rib-1 was isolated from a library of mouse genomic DNA and sequenced. This small gene contains a nontranslated exon of 52 base pairs, an intron of 791 base pairs, and a coding exon of 741 base pairs. Rib-1 transcripts were detected in parotid gland as well as in pancreas. The abundance of the transcripts were approximately 200-fold greater in pancreatic RNA than in parotid RNA. The sites of transcription initiation were mapped by primer extension and ribonuclease protection assays. One major initiation site and several minor initiation sites were identified in pancreatic RNA. Transcription in parotid appears to be initiated from the same sites. Parotid-specific transcripts were not detected. The data suggest that Rib-1 is transcribed in pancreas and parotid from the same promoter. This is in contrast with the mechanism for production of amylase in pancreas and parotid, which is accomplished by tissue specific expression of different gene copies.

Crystallization and preliminary X-ray diffraction studies of human salivary alpha-amylase

Nonglycosylated alpha-amylase, a major component of human parotid saliva, has been crystallized by the vapor diffusion technique using 2-methyl-2,4-pentanediol as the precipitant in the presence of CaCl2 at pH 9.0. The crystals are orthorhombic, space group P2(1)2(1)2(1) with unit cell dimensions of a = 53.3, b = 75.8, and c = 138.1 A. The asymmetric unit contains one amylase molecule. The solvent content is 54%. The crystals are stable to X-rays and diffract up to 2.8 A and appear to be suitable for X-ray diffraction studies.

Amylase activity increases in the yolk of fertilized eggs during incubation in chickens

Amylase activity was detected in the egg of chickens. In unfertilized eggs, no change of amylase activity was observed during 22 days incubation, however, in fertilized eggs, amylase activity increased markedly during embryonic development. The increase depended upon an increase of amylase in the yolk, not in the albumen. Isoamylases in the yolk were electrophoretically identical to those in the pancreas of the embryo or the hen.

House dust mite-derived amylase: allergenicity and physicochemical characterization

Amylase activity was found in extracts of both Dermatophagoides pteronyssinus whole mite (0.16 U/mg) and spent growth medium (0.01 U/mg) but not in unused growth medium. It was also detected in all extracts of house dust obtained from mattresses (n = 20; geometric mean, 1.95 U/gm) and in 18 extracts of dust obtained from lounge room carpets (n = 20; geometric mean, 0.54 U/gm). Although the origins of amylase in dust are unclear, enzyme activity correlated with mite counts (n = 40; r = 0.35; p less than 0.05) and Der p I concentrations (r = 0.41; p less than 0.01). Mite amylase was purified from spent growth medium by affinity chromatography, gel filtration, and chromatofocusing. It was physicochemically similar to mammalian amylase with regard to molecular weight (60,000), charge heterogeneity (isoelectric point, 5 to 7) and the capacity to bind to an organomercurial affinity matrix. The optimum pH for enzymatic activity was revealed to be 6.4. IgE immunoblot studies demonstrated that the enzyme was allergenic and that its expression was dependent on the integrity of intrachain disulfide bonds. Sera from 25% of mite-allergic children and 46% of mite-allergic adults contained specific IgE to mite amylase. IgE to amylase was associated (p less than 0.01) with increased concentrations of total mite-specific IgE determined with a direct RAST assay.

Effects of diet on amylase expression in the mosquitofish

Diets high in various carbohydrates were fed to mosquitofish,Gambusia affinis holbrooki, to determine the effects on amylase expression. Both amylase activity and amount of amylase protein were used as measures of amylase expression. Fish were fed for 21 days in one experiment, seven days in a second experiment and 24 h in a third. The first experiment compared responses of fish fed on a high-starch diet relative to a control diet. The second and third experiments compared responses on four diets relative to the control diet: maltose, starch, glucose, and glucose + cyclic adenosine monophosphate (cAMP). In the first two experiments whole visceral extracts were used. In the third experiment, gut and hepatopancreatic extracts were examined separately. Diet had a significant affect on the amount of amylase in all three experiments but affected amylase activity only in the 24 h experiment. Generally, glucose decreased amylase expression while maltose or cAMP + glucose increased it. Length of feeding period and tissue type also had significant effects on amylase expression.

Serum amylase of non-parotid and non-pancreatic origin increases on feeding in rats and may originate from the liver

1. In order to evaluate possible non-salivary contributions to the content of salivary-type amylase in the circulation, parotid glands--the only salivary source of amylase in rats--have been totally removed and the effects on serum amylase have been assessed, after fasting and at different times after feeding. 2. Despite the parotidectomy the resting level of salivary-type amylase remained the same and an increase was still found to occur on feeding. 3. Isoelectric focusing has identified additional isoforms of amylase in serum and liver distinct from those occurring in parotid saliva. 4. The liver therefore may be contributing to the fasting levels of serum amylase and to the increases that occur on feeding, in rats.

Structural relationship between the enzymatic and streptococcal binding sites of human salivary alpha-amylase

Previous studies have demonstrated that human salivary alpha-amylase specifically binds to the oral bacterium Streptococcus gordonii. This interaction is inhibited by substrates such as starch and maltotriose suggesting that bacterial binding may involve the enzymatic site of amylase. Experiments were performed to determine if amylase bound to the bacterial surface possessed enzymatic activity. It was found that over one-half of the bound amylase was enzymatically active. In addition, bacterial-bound amylase hydrolyzed starch to glucose which was then metabolized to lactic acid by the bacteria. In further studies, the role of amylase's histidine residues in streptococcal binding and enzymatic function was assessed after their selective modification with diethyl pyrocarbonate. DEP-modified amylase showed a marked reduction in both enzymatic and streptococcal binding activities. These effects were diminished when DEP modification occurred in the presence of maltotriose. DEP-modified amylase had a significantly altered secondary structure when compared with native enzyme or amylase modified in the presence of maltotriose. Collectively, these results suggest that human salivary alpha-amylase may possess multiple sites for bacterial binding and enzymatic activity which share structural similarities.

The amylase gene-enzyme system of chickens. II. Biochemical characterization of allozymes

The chicken amylase allozymes, AmyF and AmyS, were extracted from pancreatic tissues of AmyF/F and AmyS/S individuals and purified. Activities were measured under various reaction conditions (= treatments) to assess whether the allozymes were functionally different. The amylases had properties typical of alpha-amylases, i.e., both were inhibited by ethylenediaminetetraacetate and alpha-amylase inhibitor from wheat, had pH optima between 7.0 and 8.0, and could utilize a variety of substrates containing alpha 1,4 linkages. The amylases were also found to be inhibited by potassium phosphate buffer and p-chloromercuribenzoate. In terms of substrate specificity, both amylases could utilize all of the substrates tested with activity observed in the following order: amylopectin greater than potato starch greater than dextrin greater than glycogen greater than amylose. Statistical analysis indicated significant functional differences between the two allozymes in terms of specific activities, substrate specificities, and inhibitor sensitivities. AmyF had a significantly lower specific activity than did AmyS. The amylases responded differently to the substrate amylose, with AmyF better able to digest this substrate. AmyS was less sensitive than AmyF to alpha-amylase inhibitor from wheat.

Ability to bind salivary alpha-amylase discriminates certain viridans group streptococcal species

A collection of 144 viridans group streptococcal strains recently characterized as part of a taxonomic study was examined for the ability to bind salivary alpha-amylase. This property was found in most strains of Streptococcus gordonii and Streptococcus mitis and in occasional strains of Streptococcus anginosus and Streptococcus salivarius. In contrast, all strains of Streptococcus sanguis, Streptococcus oralis, Streptococcus vestibularis, and Streptococcus mutans lacked alpha-amylase-binding capacity. A rapid and easy assay described in this paper may be an important supplementary test for identification of oral streptococci.

An ultrastructural analysis of the dispersed cell phase during development of the annual fish, Cynolebias

Cell ultrastructure was investigated during the dispersion phase of development in the annual fish Cynolebias. Three cellular populations encompass the yolk mass during dispersion, namely, 1) the yolk syncytial layer (YSL) or periblast, which lies directly over the surface of the yolk; 2) the deep blastomeres of the blastoderm, which engage in morphogenetic movements on the surface of the YSL and beneath the enveloping layer prior to forming the future embryo; and 3) the enveloping layer (EVL) of the blastoderm, which is a cohesive epithelium that forms the outermost cell layer of the blastoderm. Deep blastomeres contain numerous mitochondria and scattered glycogen rosettes that appear to function in the utilization of energy reserves. These cells also possess surface extensions such as filopodia and ruffles. Numerous microfilaments running parallel to the plasma membrane occur in cell extensions and in the cortical cytoplasm of neighboring blastomeres. In bleb-like extensions such as ruffles, microfilamentous stress fibers run parallel to the plane of the plasma membrane and prevent cellular organelles from entering the hyaline cap of the ruffle. Deep blastomeres also have basal projections that contain glycogen as well as pits in the basal membrane. Blastomeres move about using the YSL as a substrate. The YSL possesses specializations for nutrient uptake, storage, and transport such as numerous multivesicular bodies and large amounts of glycogen. Glycogen, in the rosette form, occurs in extraordinary amounts, virtually occluding the cytoplasm. Glycogen reserves are postulated to serve as an energy source during diapause. Glycogen is sometimes contained within villous projections that extend from the apical surface of the YSL. This configuration suggests the possibility of glycogen transport to the overlying deep blastomeres. Specializations of the EVL include apical tight junctions and basal lateral zonulae adherentes that interdigitate with those of adjacent EVL cells. The EVL serves as an impermeable membrane that protects the developing egg from the vicissitudes of its environment.

Tissue-specific distribution of amylase in the mosquitofish (Gambusia affinis holbrooki)

Tissue-specific expression of alpha-amylase (E.C.3.2.1; α 1,4-glucan-4-glucano-hydrolase) was studied in the mosquitofish (Gambusia affinis holbrooki). Gut activity patterns, immunohistochemical distribution in the hepatopancreas and tissue-specific activities and amount of amylase protein were characterized. In the gut, activity was observed all along the gut and no variation in this pattern was observed in individuals from two natural populations. In the hepatopancreas, amylase is found in pancreatic tissue. Highest amylase activity was observed in gut tissue but highest amount of amylase protein was found in the hepatopancreas.

Alpha-amylase gene transcription in tissues of normal dog

We studied the distribution of alpha-amylase mRNA in normal dog tissues by northern blotting (NB) and reverse transcription-polymerase chain reaction (RT-PCR) with human pancreatic (AMY2) and salivary (AMY1) alpha-amylase cDNA-specific primers. Analysis of poly(A+) RNA from various normal tissues by NB indicated the presence of detectable levels of alpha-amylase mRNA transcripts only in pancreas. Dot-blot analysis of DNA amplified with primers common to both (human) isoamylase mRNAs showed presence of alpha-amylase gene transcripts not only in pancreas but also in liver, small intestine, large intestine and fallopian tube. Traces of amylase gene transcripts were also observed in ovary, uterus and lung. Interestingly, amylase transcripts were not detectable in the parotid gland by NB or RT-PCR. We have also localized alpha-amylase mRNA transcripts to dog pancreas by in situ transcription and in situ hybridization. Our results suggest that there is high degree of homology between the alpha-amylase mRNA sequences in dog and human at least in the exon 3-4 regions of the human gene.

Chloride binding proteins: mechanistic implications for the oxygen-evolving complex of Photosystem II

Chloride plays a key role in activating the photosynethetic oxygen-evolving complex (OEC) of Photosystem II, but the OEC is only one of many enzymes affected by this anion. Some of the mechanistic features of Cl(-) involvement in water-splitting resemble those of other proteins whose structure and chemistry are known in detail. An overview of the similarities and differences between these Cl(-)-binding systems is presented.

Characterization of salivary alpha-amylase binding to Streptococcus sanguis

The purpose of this study was to identify the major salivary components which interact with oral bacteria and to determine the mechanism(s) responsible for their binding to the bacterial surface. Strains of Streptococcus sanguis, Streptococcus mitis, Streptococcus mutans, and Actinomyces viscosus were incubated for 2 h in freshly collected human submandibular-sublingual saliva (HSMSL) or parotid saliva (HPS), and bound salivary components were eluted with 2% sodium dodecyl sulfate. By sodium dodecyl sulfate-polyacrylamide gel electrophoresis and Western transfer, alpha-amylase (EC 3.2.1.1) was the prominent salivary component eluted from S. sanguis. Studies with 125I-labeled HSMSL or 125I-labeled HPS also demonstrated a component with an electrophoretic mobility identical to that of alpha-amylase which bound to S. sanguis. Purified alpha-amylase from human parotid saliva was radiolabeled and found to bind to strains of S. sanguis genotypes 1 and 3 and S. mitis genotype 2, but not to strains of other species of oral bacteria. Binding of [125I]alpha-amylase to streptococci was saturable, calcium independent, and inhibitable by excess unlabeled alpha-amylases from a variety of sources, but not by secretory immunoglobulin A and the proline-rich glycoprotein from HPS. Reduced and alkylated alpha-amylase lost enzymatic and bacterial binding activities. Binding was inhibited by incubation with maltotriose, maltooligosaccharides, limit dextrins, and starch.

Purification of lingual amylase from serous glands of rat tongue and characterization of rat lingual amylase and lingual lipase

Lingual amylase and lingual lipase, two digestive enzymes that are secreted from lingual serous glands (von Ebner's), were simultaneously purified from rat lingual serous glands with hydrophobic chromatography used as the final step. This method, previously developed for the purification of lingual lipase, includes homogenization of rat lingual serous glands, 100,000 g centrifugation, ammonium sulfate precipitation of proteins, and extraction of lipids with acetone at -20 degrees C, followed by hydrophobic chromatography on ethyl agarose or Agethane. Amylase was eluted after the elution of proteins that did not interact with the hydrophobic gel at pH 6.3. Lingual lipase was eluted with a solution containing micelles of taurodeoxycholate, monoolein, and oleic acid. Analysis of each of the purified enzymes by SDS-polyacrylamide gel electrophoresis revealed one band at Mr = 59,000 for amylase and one band at Mr = 51,000 for lingual lipase. Isoelectric focusing of amylase indicated a strong band at pI = 5.0 and two very faint bands at pI = 4.9 and 4.8, possibly isozymes or deamidated protein. Amino acid and hexosamine analyses were performed on the enzymes after electroelution from SDS-polyacrylamide gels. Both lingual lipase and lingual amylase had a high content of dicarboxylic (free and amide) amino acids. For lingual lipase and lingual amylase, the % molar ratios of aspartic acid/asparagine were 15.35 and 15.10, and the % molar ratios of glutamic acid/glutamine were 7.07 and 7.20, respectively. Lingual amylase was very similar to rat parotid, pancreatic, and mouse salivary amylases, except that it contained more proline (11.03% molar ratio).(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of secretory nerve stimulation on the movement of rat parotid amylase into the circulation

Stimulation of the nerves to the rat parotid gland demonstrated that increases in serum amylase levels can originate exclusively from this gland. However, whilst parasympathetic nerve stimulation caused a significant movement of parotid amylase into the blood, sympathetic nerve stimulation did not, despite the higher concentration of amylase in the saliva evoked. Experiments in which conscious animals were fed for a short period showed that parotid amylase reaches the blood during normal activity. The mechanisms underlying the movement of parotid amylase into the circulation are still unknown but there appears to be some dependence on the volume of saliva being produced.

The amylase gene-enzyme system of fishes. I. Developmental expression of amylase in the mosquitofish

The objective of this study is to examine the effects of developmental stage on amylase expression in the mosquitofish (Gambusia affinis holbrooki, Poeciliidae). Expression was characterized in terms of amylase activity and amount of amylase protein in five developmental stages: early, mid, and late embryos, 5-day-old juveniles, and adults. Two measures of activity were used: a starch-iodine assay, which measures the change in substrate, and the dinitrosalicyclic acid (DNSA) assay, which measures the change in product. To measure changes in the amount of amylase, the enzyme-linked immunosorbent assay (ELISA) was used. Highest activity and amount was observed in the adult stage. In general, both increased with development. While the two activity measures were positively correlated, these were only weakly correlated with the amount of amylase. Possible reasons for these weak correlations between amylase activity and amount are discussed.

An amylase gene from Drosophila pseudoobscura is expressed in Escherichia coli. Functional selection and biochemical comparisons of the fly- and clone-produced amylases

An amylase gene from Drosophila pseudoobscura was isolated from a genomic library constructed in pBR322 and cloned in Escherichia coli by selecting for the ability of its product to hydrolyze starch, a carbon source not normally utilized by E. coli. Hybridization of pAMY17F to D. pseudoobscura polytene chromosomes shows a positive signal at the amylase pseudogene locus (bank 78, chromosome 3). The chimeric plasmid pAMY17F, has been altered in such a way as to increase amylase expression. Southern and Northern hybridizations to the cloned amylase DNA indicate that the source of the gene is from D. pseudoobscura. Biochemical properties such as pH optima, substrate specificities, electrophoretic analyses, inhibitor sensitivities, heat stabilities, temperature responsiveness and molecular weights indicate that the amylases produced by the fly and bacterial clone are similar and have similar properties. It appears that E. coli/pAMY17F is producing an amylase like that found in D. pseudoobscura.

The proper role of nerves in salivary secretion: a review

Consideration of the history of this subject has created a perspective which helps one to appreciate how errors in thinking have occurred and why some have persisted, despite subsequent improvements in information. The most enduring misconception has been that the drying of the mouth under stress is due to sympathetic inhibitory fibers, a view that must be eradicated, for such fibers do not exist. The inhibition is due to central influences from higher centers acting on the salivary centers and thereby suppressing reflex activity. Wide variations exist in the neuro-effector arrangements and in the cellular responses in different glands from different species. Myoepithelial cells are usually contracted by both parasympathetic and sympathetic nerves. The blood vessels also receive a dual innervation, but parasympathetic impulses cause vasodilatation as part of secretion, whereas the sympathetic vasoconstrictor fibers are part of a more generalized vascular control system and not a direct part of the reflex secretory sympathetic pathway. Parasympathetic drive usually provides the main stimulus for fluid formation by parenchymal cells, whereas sympathetic nerves tend to increase the output of pre-formed components from certain cells. Absence of nerve impulses causes variable atrophic and other metabolic effects on the parenchymal cells. Evidence is beginning to accrue that certain nerve impulses may influence resynthetic activities. Vacuolation, often found experimentally after strong stimulation, also occurs to a variable extent in certain cells as a normal part of reflex secretion and may therefore have an effect on the components entering the saliva. If rupture of vacuoles occurs, then this may contribute to the salivary amylase that is present in the blood. Recent evidence points to the possibility that, even in a monomorphic gland, not all of the components necessarily enter nerve-induced saliva in "parallel" proportions. Consideration of current information has enabled some provisional generalizations about the roles of the secretory nerves to be suggested in the summary, but they must not be considered immutable.

Molecular cloning of alpha-amylase genes from Drosophila melanogaster. I. Clone isolation by use of a mouse probe

A cloned alpha-amylase cDNA sequence from the mouse is homologous to a small set of DNA sequences from Drosophila melanogaster under appropriate conditions of hybridization. A number of recombinant lambda phage that carry homologous Drosophila genomic DNA sequences were isolated using the mouse clone as a hybridization probe. Putative amylase clones hybridized in situ to one or the other of two distinct sites in polytene chromosome 2R and were assigned to one of two classes, A and B. Clone lambda Dm32, representing class A, hybridizes within chromosome section 53CD. Clone lambda Dm65 of class B hybridizes within section 54A1-B1. Clone lambda Dm65 is homologous to a 1450- to 1500-nucleotide RNA species, which is sufficiently long to code for alpha-amylase. No RNA homologous to lambda Dm32 was detected. We suggest that the class B clone, lambda Dm65, contains the functional Amy structural gene(s) and that class A clones contain an amylase pseudogene.

All-reagent test tablets and method for rapid and selective alpha-amylase iodometric determination

The new type of test tablets (Iodocrom) for alpha-amylase assay contain crosslinked (CL)-amylose or CL-starch (specific substrates for alpha-amylase only) and the reagent (KIO3/KI) generating iodine (in acidic medium, when the reaction is stopped). The method--amyloclastic in nature--is based on selective action of alpha-amylase on the CL-substrate liberating soluble polysaccharide chains large enough and in a conformation suitable to allow the formation of iodine inclusion complexes. Unlike the classical iodometric methods, the reaction is followed by an increase in iodine complex blue color. The method has some common points with the well-known chromogenic (e.g., Phadebas) methods. Both use insoluble substrates which are not susceptible to attack by exoamylases and in both cases the enzymatic reaction is followed by the release of soluble products. The amounts of these released chains and the absorbances of their inclusion complexes with iodine are in a linear dependence with the enzyme concentration (activity).

Regional assignment of human amylase (AMY) to p22----p21 of chromosome 1

A human genomic DNA segment (lambda hal) which hybridizes with rat pancreatic amylase cDNA was used to regionally assign amylase genes in human-mouse somatic cell hybrids. The assignment of amylase genes to chromosome 1 was confirmed and regionally mapped to the short arm region p22.1----p21 using a cell hybrid retaining a translocation involving chromosome 1 [46,XX,t(1;2)(p21;q37)]. Restriction length polymorphisms at the amylase loci are reported for gene linkage studies.

Sex-limited genetic variation in a mouse salivary protein

This report describes a gene which influences the electrophoretic mobility of a protein in the salivas of adult mice. Three categories of phenotype have been observed: the two single-banded types, F (Fast) and S (Slow), and the two-banded type, SF (Slow-Fast), with the two bands represented in varying proportions. All females, regardless of age or strain, and all males before puberty show only the F phenotype. Males of the BALB/c and C57BL/6J strains show the F phenotype throughout puberty and adult life, whereas males of the C3H/St and C57BL/KsJ strains show the SF phenotype in puberty and the S phenotype in adult life. We have designated this variation the sex-limited saliva pattern (Ssp). The results from genetic crosses indicate that the variation among the strains is determined by an autosomal locus, Ssp, with two alleles, SspS and SspF, where SspS is dominant to SspF. Testosterone treatment can accelerate the acquisition of the S type in males of the strains C3H/St and C57BL/KsJ and also induces that phenotype in C3H/St females and C57BL/6J males. Thus it appears that the observed strain-specific differences reflect a genetic variation in androgen levels and/or androgen sensitivity rather than variation in a structural gene.

Evidence of duplication of the human salivary amylase gene

Isoelectric focusing of human parotid saliva reveals different alpha-amylase patterns reflecting qualitative and quantitative variations. A puzzling pattern, which shows three different amylase gene products, was found in four individuals. Based on this observation a model is presented in which the salivary amylase gene is duplicated. Family studies show that the AMY1*A2 gene forms a haplotype with the normal gene, AMY1*A1, whereas the AMY1*A3 gene still exists in a single form. The absence of homozygote 2-2 in offspring of 1-2 X 1-2 marriages and in population material, and the fact that the variant protein makes up about only 20-30% of the total amylase protein in heterozygotes can be considered as additional evidence supporting the hypothesis. The possibility that cis-acting regulatory variants are involved in the patterns with quantitative variation is discussed.