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PubMed1989

Dietary interactions of lima bean (Phaseolus lunatus) trypsin inhibitor, haemagglutinin and cyanide. Part 2. Effect on pancreatic and intestinal alpha-amylase (EC 3.21.1.1) in growing albino rats.

A total of 108 growing albino rats was used to evaluate the dietary interactions of the major lima bean antinutritional factors trypsin inhibitor (TI), haemagglutinin (Hgg) and cyanide (CN) with respect to their effects on pancreatic and intestinal alpha-amylase activities. The results indicate that when fed at the same level of activity as found in the raw lima bean (RLB) these factors had no significant (p greater than 0.05) influence on pancreatic alpha-amylase activity whether acting individually or in combination. However, when acting alone, CN appeared to depress pancreatic amylase level more than when interacting with TI or Hgg or both. Amylase activity was significantly (p less than 0.01) depressed by the dietary treatments in both the small and large intestine while caecal levels were not. The most severe depression in amylase activity was elicited by the RLB diet. The haemagglutinin-containing diets appeared generally associated with lower levels of intestinal amylase activity. From the present finding it is suggested that these factors alone cannot fully account for the magnitude of the depression of intestinal amylase activity which is contingent upon the ingestion of RLB by experimental rats.

Animals↗
PubMed1994

Heterogeneity and contact-dependent regulation of amylase release by individual acinar cells.

We have used a reverse hemolytic plaque assay to investigate the amylase release of single and aggregated pancreatic acinar cells. We have found that a minority of single acinar cells released detectable amounts of amylase under basal conditions and were modestly stimulated, in a dose-dependent manner, during a 30-min exposure to concentrations of carbamylcholine (CCh) ranging from 10(-8) to 10(-5) M. This stimulation was largely accounted for by the recruitment of additional secreting cells, rather than by a significant increase in their individual secretory output. We have also observed that aggregates comprising two to five acinar cells secreted more frequently and released more amylase than single acinar cells in the presence of each of the CCh concentrations tested. Under both basal conditions and following CCh stimulation, the proportion of secreting aggregates and their amylase output increased linearly with the aggregate size. Under basal conditions as well as in the presence of secretagogue concentrations in the 10(-8) - 10(-7) M range, individual cells contributed similarly to amylase secretion whether they were single or part of aggregates. By contrast, following stimulation by 10(-6) - 10(-5) M CCh, aggregated cells showed a much higher average secretion than single cells. Investigating the mechanism of this contact-dependent effect, we found that 10(-3) M heptanol did not significantly modify the secretion of single cells and markedly promoted the basal amylase release of acinar cell pairs. This effect was associated with a marked reduction in gap junctional communication between acinar cells, as evaluated by microinjection of Lucifer yellow, and was not observed during exposure to high concentrations of CCh, which also reduced junctional communication. These data show that pancreatic acinar cells are intrinsically heterogeneous in their ability to release amylase and that their basal as well as stimulated secretion are promoted by the establishment of direct intercellular contacts. Our experiments also suggest that junctional coupling contributes to the contact-dependent mechanism which enhances the recruitment of secreting cells and their individual output. These observations strengthen the view that direct interactions between acinar cells are essential in the control of pancreatic secretion.

Amylases↗
PubMed1995

The structure of human pancreatic alpha-amylase at 1.8 A resolution and comparisons with related enzymes.

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.

Amino Acid Sequence↗
PubMed1995

Crystallization, molecular replacement solution, and refinement of tetrameric beta-amylase from sweet potato.

Sweet potato beta-amylase is a tetramer of identical subunits, which are arranged to exhibit 222 molecular symmetry. Its subunit consists of 498 amino acid residues (Mr 55,880). It has been crystallized at room temperature using polyethylene glycol 1500 as precipitant. The crystals, growing to dimensions of 0.4 mm x 0.4 mm x 1.0 mm within 2 weeks, belong to the tetragonal space group P4(2)2(1)2 with unit cell dimensions of a = b = 129.63 A and c = 68.42 A. The asymmetric unit contains 1 subunit of beta-amylase, with a crystal volume per protein mass (VM) of 2.57 A3/Da and a solvent content of 52% by volume. The three-dimensional structure of the tetrameric beta-amylase from sweet potato has been determined by molecular replacement methods using the monomeric structure of soybean enzyme as the starting model. The refined subunit model contains 3,863 nonhydrogen protein atoms (488 amino acid residues) and 319 water oxygen atoms. The current R-value is 20.3% for data in the resolution range of 8-2.3 A (with 2 sigma cut-off) with good stereochemistry. The subunit structure of sweet potato beta-amylase (crystallized in the absence of alpha-cyclodextrin) is very similar to that of soybean beta-amylase (complexed with alpha-cyclodextrin). The root-mean-square (RMS) difference for 487 equivalent C alpha atoms of the two beta-amylases is 0.96 A. Each subunit of sweet potato beta-amylase is composed of a large (alpha/beta)8 core domain, a small one made up of three long loops [L3 (residues 91-150), L4 (residues 183-258), and L5 (residues 300-327)], and a long C-terminal loop formed by residues 445-493. Conserved Glu 187, believed to play an important role in catalysis, is located at the cleft between the (alpha/beta)8 barrel core and a small domain made up of three long loops (L3, L4, and L5). Conserved Cys 96, important in the inactivation of enzyme activity by sulfhydryl reagents, is located at the entrance of the (alpha/beta)8 barrel.

Amino Acid Sequence↗
PubMed1996

Evolution of beta-amylase: patterns of variation and conservation in subfamily sequences in relation to parsimony mechanisms.

Soybean and sweet potato beta-amylases are structured as alpha/beta barrels and the same kind of folding may account for all known beta-amylases. We provide a comprehensive analysis of both protein and DNA (coding region) sequences of beta-amylases. The aim of the study is to contribute to the knowledge of the evolutionary molecular relationships among all known beta-amylases. Our approach combines the identification of the putative eightfold structural core formed by beta-strands with a complete multi-alignment analysis of all known sequences. Comparing putative beta-amylase (alpha/beta)8 cores from plants and microorganisms, two differentiated versions of residues at the packing sites, and a unique set of eight identical residues at the C-terminal catalytical site are observed, indicating early evolutionary divergence and absence of localized three-dimensional evolution, respectively. A new analytical approach has been developed in order to work out conserved motifs for beta-amylases, mostly related with the enzyme activity. This approach appears useful as a new routine to find sets of motifs (each set being known as a fingerprint) in protein families. We demonstrate that the evolutionary mechanism for beta-amylases is a combination of parsimonious divergence at three distinguishable rates in relation to the functional signatures, the barrel scaffold, and alpha-helix-containing loops.

Amino Acid Sequence↗
PubMed2001

Efficient expression, purification and characterization of mouse salivary alpha-amylase secreted from methylotrophic yeast, Pichia pastoris.

We constructed a secretion vector of mouse salivary alpha-amylase, pPAM, using the AOX1 promoter-terminator and the secretion signal of 128 kDa pGKL killer protein, for an alternative yeast, Pichia pastoris. Taking advantage of multicopy insertion of the expression cassette and optimized growth conditions, we succeeded in highly efficient extracellular production (approximately 240 microg/ml) of mouse alpha-amylase in the 10 ml scale by conventional flask culture: this efficiency was about 90-fold higher than that of Saccharomyces cerevisiae. Growth temperature of cells was critical for efficient production of alpha-amylase. P. pastoris transformants secreted both core-glycosylated and non-glycosylated alpha-amylase molecules with a glycosylated:non-glycosylated ratio of about 20:80. Both glycosylated and non-glycosylated alpha-amylases were purified separately to apparent homogeneity. The signal sequence was correctly processed in both species, and the molecular masses of glycosylated and non-glycosylated alpha-amylase were determined to be 58 600 and 56 300, respectively, by mass spectrometry. We further studied the outer chain glycosylation of engineered mouse alpha-amylase secreted by P. pastoris.

Amino Acid Sequence↗
PubMed2000

Effects of an inhibitor of myosin light chain kinase on amylase secretion from rat pancreatic acini.

Ca(2+)/calmodulin-dependent protein (CaM) kinases play an important role in Ca(2+)-mediated secretory mechanisms. Previously, we demonstrated that a CaM kinase II inhibitor KN-62 had a small inhibitory effect on amylase secretion stimulated by CCK. In the present study, we investigated the effects of a myosin light chain kinase (MLCK) inhibitor on amylase secretion and Ca(2+) signaling in rat pancreatic acini. A specific inhibitor of MLCK, wortmannin, inhibited amylase secretion stimulated by CCK-8 (30 pM) in a concentration-dependent manner. Wortmannin (10 microM) had no effects on basal secretion but reduced amylase secretion stimulated by CCK-8 (30 pM) by 67 +/- 3%. Wortmannin inhibited amylase secretion stimulated by calcium ionophore (A23187) and phorbol ester (TPA). Wortmannin also inhibited amylase response to thapsigargin by 76 +/- 8% and to both thapsigargin and TPA by 52 +/- 10%. Ca(2+) oscillations evoked by CCK-8 (10 pM) were inhibited by wortmannin (10 microM). Wortmannin had a little inhibitory effect on an initial rise in [Ca(2+)](i), and abolished a subsequent sustained elevation of [Ca(2+)](i) evoked by 1 nM CCK-8. In conclusion, MLCK plays a crucial role in amylase secretion from pancreatic acini and regulates Ca(2+) entry from the extracellular space.

Amylases↗
PubMed1998

Crystal structure of yellow meal worm alpha-amylase at 1.64 A resolution.

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.

Amino Acid Sequence↗
PubMed2000

Simulation of regulated exocytosis of amylase from salivary parotid acinar cells by a consecutive reaction model comprising two sequential first-order reactions.

Amylase secretion from parotid acinar cells results from stimulus-regulated fusion of apical membrane and secretory granules that contain amylase. The time course of amylase secretion induced by various secretagogues has been reported. Calcium-mobilizing agonists such as carbamylcholine and substance P induce rapid and transient secretion while cAMP-mobilizing agonists such as isoproterenol cause long-term secretion. Combination of these two types of agonists results in a rapid and high rate of secretion. To explain the various time courses of these stimulations, it was assumed that amylase secretion is a consecutive reaction that consists of two first-order reactions. It was postulated that secretory granules were classified into three states: (A) pre-docked, (B) docked, and (C) fusion. The simple simulation could explain the time course of amylase secretion induced by various secretagogues by simply changing the rate constants for docking (reaction A to B) and fusion (reaction B to C) steps. It was also found that calcium mainly enhances the last fusion step and that cAMP activates the docking step. The amount of docked granules is estimated to be quite small, which accounts for why amylase secretion is regulated mainly by cAMP. The effects of the two types of secretagogues were synergistic, meaning that their intracellular signaling pathways are independent. At the same time, this also suggests that basal and enhanced secretion induced by two types of agonists have the same exocytotic process and that two stimuli independently activate the same machinery that mediates docking or fusion. This simulation is useful in analysis of the effects of secretion modulators and the molecular mechanism of amylase secretion.

Amylases↗
PubMed1996

Sugars act as signal molecules and osmotica to regulate the expression of alpha-amylase genes and metabolic activities in germinating cereal grains.

The molecular mechanisms that initiate and control the metabolic activities of seed germination are largely unknown. Sugars may play important roles in regulating such metabolic activities in addition to providing an essential carbon source for the growth of young seedlings and maintaining turgor pressure for the expansion of tissues during germination. To test this hypothesis, we investigated the physiological role of sugars in the regulation of alpha-amylase gene expression and carbohydrate metabolism in embryo and endosperm of germinating rice seeds. RNA gel blot analysis revealed that in the embryo and aleurone cells, expression of four alpha-amylase genes was differentially regulated by sugars via mechanisms beyond the well-known hormonal control mechanism. In the aleurone cells, expression of these alpha-amylase genes was regulated by gibberellins produced in the embryo and by osmotically active sugars. In the embryo, expression of two alpha-amylase genes and production of gibberellins were transient, and were probably induced by depletion of sugars in the embryo upon imbibition, and suppressed by sugars influx from the endosperm as germination proceeded. The deferential expression of the four alpha-amylase genes in the embryo and aleurone cells was probably due to their markedly different sensitivities to changes in tissue sugar levels. Our study supports a model in which sugars regulate the expression of alpha-amylase genes in a tissue-specific manner: via a feedback control mechanism in the embryo and via an osmotic control mechanism in the aleurone cells. An interactive loop among sugars, gibberellins, and alpha-amylase genes in the germinating cereal grain is proposed.

Carbohydrates↗
PubMed1994

Protein engineering in the alpha-amylase family: catalytic mechanism, substrate specificity, and stability.

Most starch hydrolases and related enzymes belong to the alpha-amylase family which contains a characteristic catalytic (beta/alpha)8-barrel domain. Currently known primary structures that have sequence similarities represent 18 different specificities, including starch branching enzyme. Crystal structures have been reported in three of these enzyme classes: the alpha-amylases, the cyclodextrin glucanotransferases, and the oligo-1,6-glucosidases. Throughout the alpha-amylase family, only eight amino acid residues are invariant, seven at the active site and a glycine in a short turn. However, comparison of three-dimensional models with a multiple sequence alignment suggests that the diversity in specificity arises by variation in substrate binding at the beta-->alpha loops. Designed mutations thus have enhanced transferase activity and altered the oligosaccharide product patterns of alpha-amylases, changed the distribution of alpha-, beta- and gamma-cyclodextrin production by cyclodextrin glucanotransferases, and shifted the relative alpha-1,4:alpha-1,6 dual-bond specificity of neopullulanase. Barley alpha-amylase isozyme hybrids and Bacillus alpha-amylases demonstrate the impact of a small domain B protruding from the (beta/alpha)8-scaffold on the function and stability. Prospects for rational engineering in this family include important members of plant origin, such as alpha-amylase, starch branching and debranching enzymes, and amylomaltase.

Amino Acid Sequence↗
PubMed1993

Functional conservation of a glucose-repressible amylase gene promoter from Drosophila virilis in Drosophila melanogaster.

Previous studies have demonstrated that the expression of the alpha-amylase gene is repressed by dietary glucose in Drosophila melanogaster. Here, we show that the alpha-amylase gene of a distantly related species, D. virilis, is also subject to glucose repression. Moreover, the cloned amylase gene of D. virilis is shown to be glucose repressible when it is transiently expressed in D. melanogaster larvae. This cross-species, functional conservation is mediated by a 330-bp promoter region of the D. virilis amylase gene. These results indicate that the promoter elements required for glucose repression are conserved between distantly related Drosophila species. A sequence comparison between the amylase genes of D. virilis and D. melanogaster shows that the promoter sequences diverge to a much greater degree than the coding sequences. The amylase promoters of the two species do, however, share small clusters of sequence similarity, suggesting that these conserved cis-acting elements are sufficient to control the glucose-regulated expression of the amylase gene in the genus Drosophila.

Animals↗
PubMed1994

Purification of secreted alpha-amylases by immunoaffinity chromatography with cross-reactive antibody.

Two isozymes of rice alpha-amylases expressed and secreted by recombinant yeast were purified by immunoaffinity chromatography by using cross-reactive antibody. Antibodies raised against partially purified barley alpha-amylase adsorbed rice alpha-amylases in fermentation broth by a cross-reaction. By use of these antibodies as ligands, rice alpha-amylases were concentrated and purified to a high degree in one-step immunoaffinity chromatography. Because of the differences in the contaminating impurities between the barley alpha-amylase (antigen) from barley malt and rice alpha-amylases (target protein) secreted from yeast, the high purity of eluted alpha-amylases was attained without the use of highly purified antigen for immunization. Utilization of cross-reactive antibodies in immunoaffinity chromatography is useful for the purification of recombinant proteins in the absence of a sufficient amount and high enough purity of the target proteins to be purified.

Antibodies↗
PubMed1981

Comparative genetics of hamster amylases.

Syrian (Mesocricetus auratus) and Chinese (Cricetulus griseus) hamsters were phenotyped by electrophoresis for salivary and pancreatic amylases. Syrian hamsters possess two salivary amylase electromorphs, the more anodal (fast) being invariant in 250 outbred and 17 representatives of 5 highly inbred lines. The slow electromorph had activity equal to that of the fast amylase (heavy), or had distinctly less activity (light), or was absent (null). The slow electromorph is inherited as an autosomal semidominant trait with two alleles. Amys and Amyo. Amys homozygotes produce heavy, Amyo homozygotes null, and heterozygotes light phenotypes, respectively. Five inbred strains of hamsters were homozygous Amyo. Pancreatic amylase was monomorphic. Eight outbred Chinese hamsters showed no salivary amylase activity with electrophoresis, but slight activity with long incubation on starch-agar plates. However, pancreatic amylase activity in the Chinese hamster exceeded that in Syrian hamsters. Site duplication and apparent "null" alleles for amylase genes occur in muroid rodents. The evolutionary implications are discussed.

Amylases↗
PubMed1983

The effect of calmodulin antagonists on amylase release from the rat parotid gland in vitro.

The effect of several calmodulin antagonists on the release of alpha-amylase (EC 3.2.1.1) from rat parotid gland minces was investigated as an approach to determine whether calmodulin has a role in the stimulus-secretion coupling mechanism in this tissue. The phenothiazines, trifluoperazine, chlorpromazine, and thioridazine, failed to inhibit amylase release induced by N6,O2'-dibutyryl adenosine 3':5'-cyclic monophosphate. All three phenothiazines increased basal amylase release at high concentrations. This release was independent of cellular energy, indicating that the release was probably due to the membrane perturbing properties of these compounds rather than their ability to antagonize calmodulin. R24571, a more potent calmodulin antagonist, also failed to inhibit amylase release induced by N6,O2'-dibutyryl adenosine 3':5'-cyclic monophosphate but increased basal amylase release. A different calmodulin antagonist, N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide, partially inhibited release while 8-(N,N-diethylamino)-octyl 3,4,5-trimethoxybenzoate hydrochloride (TMB-8) completely blocked the amylase release induced by the cyclic AMP derivative. However, concentrations of TMB-8 inhibiting amylase release drastically reduced the ATP concentration of rat parotid minces, suggesting that the inhibition of secretion was due to toxic effects of TMB-8 on parotid cells rather than the ability of the compound to antagonize calmodulin. The use of calmodulin antagonists has therefore failed to implicate calmodulin as an intermediate in the stimulus-secretion coupling mechanism of the rat parotid gland.

Adenosine Triphosphate↗
PubMed1993

Serum amylase and lipase concentrations and lipase/amylase ratio in assessment of etiology and severity of acute pancreatitis.

We studied the behavior of serum amylase and lipase in 66 consecutive patients with acute pancreatitis in order to assess the ability of these tests and of the serum lipase-amylase ratio to establish the etiology and predict the severity of acute pancreatitis. Forty-two patients had biliary acute pancreatitis, 14 had alcoholic acute pancreatitis, and the remaining 10 nonbiliary, nonalcoholic (NBNA) acute pancreatitis. Serum amylase and lipase were abnormally high in all patients. The elevations of both serum amylase and lipase were significantly lower in patients with alcoholic pancreatitis than in those with biliary pancreatitis, although a considerable overlap was observed between the two groups. No statistically significant differences were found between NBNA patients and those with either biliary or alcoholic forms of the disease. The serum lipase-amylase ratios in patients with alcoholic pancreatitis ranged from 0.2 to 5.6, in those with biliary pancreatitis from 0.1 to 7.9, and in those with NBNA pancreatitis from 0.1 to 4.4. These differences were not statistically significant. No differences in serum enzyme levels were observed among patients without apparent imaging signs of acute pancreatitis (N = 20), those with signs of pancreatic edema (N = 36), and those with necrotizing pancreatitis (N = 10). The results indicate that serum amylase and lipase concentrations are not able to establish either the etiology or to predict the severity of acute pancreatitis as assessed by imaging techniques. Furthermore, the serum lipase-amylase ratio is not useful in distinguishing acute episodes of alcoholic from nonalcoholic acute pancreatitis.

Acute Disease↗
PubMed1996

[Alpha-amylase inhibitors and soluble dietary fiber in rye: partial purification and effect on postprandial glycemia].

The protein inhibitor of the alpha-amylase (D-type) and the soluble arabinoxylan of rye (Var. Clou) were isolated from flour and bran, respectively. The isolation of the alpha-amylase inhibitor involves the extraction of rye flour in aqueous CaCl2-solution (2 x 10(-3) M containing the hemicellulase preparation Veron HE (2 g/100 g flour), dialysis and lyophilization (preparation I) and further fractionation with ammonsulfate, using the fraction 20-50% for isolation (preparation II). The arabinoxylan isolation is carried out using extraction of rye bran in 80% ethanol (80 degrees C), centrifugation, aqueous extraction of the sediment, dialysis and lyophilization (preparation I). The further purification using the precipitate of the fraction 20-50% leads to preparation II. The alpha-amylase inhibitor preparation II and the arabinoxylan preparation II were applied in a diet containing wheat starch and casein and fed to diabetic and healthy rats (Levis and Wistar). The postprandial increase of glucose was determined. It was detected that the postprandial increase of glucose is influenced neither by the alpha-amylase inhibitor nor by the soluble arabinoxylan in comparison to the control experiments. However, the alpha-amylase inhibitor of wheat significantly decreases the postprandial increase of glucose. The application of a test meal with alpha-amylase inhibitor of rye to health and diabetic of type-II-volunteers showed no variation of the blood glucose values. The reduction of the increase of glucose by the soluble beta-glucan of oat cannot be confirmed for the soluble arabinoxylan of rye. We conclude that the effect of the alpha-amylase inhibitor as well as the soluble pentosan or glucan has to be examined for each cereal species.

Animals↗
PubMed1983

A simplified method for detecting macroamylasemia by measuring serum amylase activity at different reaction temperatures.

Amylase activity in serum and urine, and isoamylase, were measured in 300 patients with abdominal pain to detect cases of macroamylasemia. Of these patients, 9 had hyperamylasemia and 2 were diagnosed as cases of macroamylasemia on the basis of their amylase/creatinine clearance ratio, the gel filtration pattern of their amylase on a dextran column, and results of immunological analysis. Amylase activity in macroamylasemia is reported to show an anomalous response to increase in reaction-temperature. In this report, measurements of the temperature-activity relationships of serum amylase confirmed that the ratio of serum amylase activity at 50 degrees C to that at 25 degrees C (AMY-50 degrees C/AMY-25 degrees C ratio) in patients with macroamylasemia was higher than that in normal subjects or patients with pancreatitis. Moreover, when macromolecular amylase in the sera of patients with macroamylasemia was separated from amylase of normal molecular weight by dextran gel chromatography, it showed a significantly higher AMY-50 degrees C/AMY-25 degrees C ratio than the latter. Measurement of this AMY-50 degrees C/AMY-25 degrees C ratio seems to be a convenient and useful method for differential diagnosis of hyperamylasemia.

Amylases↗