Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.4.21.1 (chymotrypsin)
 10,938 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

This study demonstrates that a serine endopeptidase of pancreatic origin (elastase 2) circulates in human blood. A specific and highly sensitive radioimmunoassay has been developed for pancreatic elastase 2 in human serum. The inactivation of elastase 2 employed as radioiodinated tracer with an active site-specific reagent (phenylmethanesulfonyl fluoride) was necessary to prevent its binding by serum alpha1-antitrypsin and alpha2-macroglobulin while maintaining its immunoreactivity. The assay is based upon competition of standard human pancreatic elastase 2 with 125I-labeled phenylmethanesulfonyl elastase 2 for specific antibody binding sites, after which a second antibody precipitation step is used to separate bound from free 125I-labeled phenylmethanesulfonyl elastase 2. The minimum detectable concentration of elastase 2 was 0.9 ng/ml. The average normal fasting serum level determined was 71 ng/ml, approximately 80-fold greater than the minimum detectable amount. The form of radioimmunoassayable elastase 2 in normal human serum has been investigated by gel filtration of serum samples on Sephadex G-200 followed by radioimmunoassay of column fractions. The majority of the immunoreactive elastase 2 is eluted from G-200 in the void volume. While a minor amount of elastase 2 is eluted in a position consistent with alpha1-antitrypsin-elastase 2 complex, no free elastase or free proelastase is detectable. Addition of exogenous elastase 2 to normal serum prior to gel filtration on G-200 produced an increase only in the peak of radioimmunoassayable elastase bound to alpha1-antitrypsin. In vitro experiments have demonstrated that while elastase 2 bound to alpha1-antitrypsin is immunologically reactive, alpha2-macroglobulin-bound elastase 2 cross-reacts less than 2% in this radioimmunoassay. The assay has been shown to be specific for elastase 2. Human pancreatic elastase 1, anionic trypsin, chymotrypsin I, and chymotrypsin II do not cross-react in this assay system. The major advantages of this radioimmunoassay over enzymatic assays are its high sensitivity and ability to measure the enzyme in terms of its total protein concentration.
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PMID:Pancreatic elastase in human serum. Determination by radioimmunoassay. 83 29

Incubation of human serum alpha 1-antichymotrypsin with human pancreatic elastase 2 or porcine pancreatic elastase results in the complete inhibition of each enzyme as determined by spectrophotometric assays. alpha 1-Antichymotrypsin reacts much more rapidly with the human than with the porcine enzyme. The inhibitor: enzyme molar ratio, required to obtain full inhibition of enzymatic activity, is equal to 1.25/1 when alpha 1-antichymotrypsin reacts with human pancreatic elastase 2 while it is markedly higher with porcine pancreatic elastase (5.5/1). Patterns obtained by SDS/polyacrylamide gel electrophoresis of the reaction products show the formation with both enzymes of an equimolar complex (Mr near 77 000) and the release of a fragment migrating as a peptide of Mr near 5000. Moreover a free proteolytically modified form of alpha 1-antichymotrypsin, electrophoretically identical with that obtained in the reaction with cathepsin G or bovine chymotrypsin, is produced in the reaction with each elastase but in a much greater amount when alpha 1-antichymotrypsin reacts with porcine elastase than with human elastase. As a consequence of our findings, the specificity of alpha 1-antichymotrypsin, so far limited to the inhibition of chymotrypsin-like enzymes from pancreas and leukocyte origin, has to be extended to the two pancreatic elastases investigated in this work. A contribution of alpha 1-antichymotrypsin to the regulatory balance between plasma inhibitors and human pancreatic elastase 2 in pancreatic diseases is suggested.
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PMID:Human serum alpha 1-antichymotrypsin is an inhibitor of pancreatic elastases. 384 29

The total daily amount of extractable cationic trypsin, chymotrypsin, and pancreatic elastase 2 in feces and ileostomy fluids has been studied in normal individuals and healthy colectomized subjects. Quantitation was performed using immunological assays with polyethylene glycol as a fecal marker. The extractable amount of each of these enzymes in the feces of normal individuals was less than 1 mg/24 h. However, in fecal extracts from antibiotic-treated normal individuals a 100-fold increase in immunoreactive cationic trypsin was observed, while chymotrypsin and elastase 2 were only 2- to 3-fold higher. In extracts from ileostomy fluids cationic trypsin, elastase, and chymotrypsin all showed mean values in the order of 50-200 mg/24 h. The characterization of the immunoreactivity of pancreatic proteases showed no qualitative differences when measured in duodenal juice or fecal and ileostomy extracts.
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PMID:Determination of immunoreactive trypsin, pancreatic elastase and chymotrypsin in extracts of human feces and ileostomy drainage. 655 6

The substrate specificity of human pancreatic elastase 2 was investigated by using a series of peptide p-nitroanilides. The kinetic constants, kcat and Km, for the hydrolysis of these peptides revealed that this serine protease preferentially hydrolyzes peptides containing P1 amino acids which have medium to large hydrophobic side chains, except for those which are disubstituted on the first carbon of the side chain. Thus, human pancreatic elastase 2 appears to be similar in peptide bond specificity to the recently described porcine pancreatic elastase 2 [Gertler, A., Weiss, Y., & Burstein, Y. (1977) Biochemistry 16, 2709] but differs significantly in specificity from porcine elastase 1. The best substrates for human pancreatic elastase 2 were glutaryl-Ala-Ala-Pro-Leu-p nitroanilide and succinyl-Ala-Ala-Pro-Met-p-nitroanilide. However, there was little difference among substrates with leucine, methionine, phenylalanine, tyrosine, norvaline, or norleucine in the P1 position. Changes in the hydrolysis rate of peptides with differing P5 residues indicate that this enzyme has an extended binding site which interacts with at least five residues of peptide substrates. The overall catalytic efficiency of human pancreatic elastase 2 is significantly lower than that of porcine elastase 1 or bovine chymotrypsin with the compounds studied.
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PMID:Substrate specificity of human pancreatic elastase 2. 689 42

A somatostatin-14-degrading activity has been purified to homogeneity from rat pure pancreatic juice. This proteinase was concentrated more than 350-fold in a four-step procedure including ion-exchange and gel filtration. The final preparation contained a single protein with a molecular weight (M(r)) of approx. 29,000, as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The determination of its NH2-terminal sequence led us to conclude that the purified proteinase corresponds to the rat pancreatic elastase II predicted from the cDNA clone isolated by MacDonald in 1982. This anionic proteinase exhibits an isoelectric point of 5.6 and does not contain any carbohydrate moieties in its structure. The proteinase is sensitive to the trypsin inhibitors soybean trypsin inhibitor and N alpha-tosyl-L-lysine-chloromethyl ketone and also to 3,4-dichloroisocoumarin, a general elastase inhibitor. The cleavage products obtained after hydrolysis of somatostatin-14 by the purified elastase, were separated by reversed phase high performance liquid chromatography and identified by amino-acid analysis. The primary hydrolysis was trypsin-like and consisted in an opening of the cyclic structure of somatostatin-14 after the Lys-9 residue leading to the formation of a Y-shaped peptide with the same amino-acid composition as the native peptide. The initial 'trypsin-like specificity' was not observed during the secondary hydrolysis of the Y-shaped peptide; indeed the proteinase seemed more specific for a certain motif in the native peptide rather than for a specific class of amino acid, this last kind of selectivity is commonly observed with trypsin and chymotrypsin. In order to establish that the proteinase possesses an extended recognition site on the substrate rather than a specificity for a class of amino acid, the substrate specificity of the rat pancreatic elastase II was investigated with a series of para-nitroanilide peptides. The proteinase exhibits a large specificity involving peptide chain of at least four amino acids with a preference for bulky residue in P1 or P2. The Km values of 89 microM and 1567 microM obtained for somatostatin-14 and Suc-Ala-Ala-Pro-Met-pNA, respectively, indicate that elastase II has a greater affinity for the natural substrate than for synthetics. This last observation along with the substrate specificity of the proteinase leads us to propose that elastase II could be specifically involved in the regulation of biological functions of somatostatin-14 in the gastrointestinal tract.
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PMID:Purification, characterization and substrate specificity of rat pancreatic elastase II. 764 93

A specific method for pancreatic elastase II activity analysis was developed. True elastase II activity could be discriminated from that of elastase I and chymotrypsin. The postnatal development of four pancreatic proteases in the duodenal juice of children and in the pancreatic homogenates of calves and piglets was measured. The study was carried out on patients without (14 children) and with (5 children) pancreatic insufficiency. Calves and piglets were either milk-fed or weaned until slaughter at different ages. Profiles of enzyme development were globally similar in milk-fed piglets and calves, while in children without pancreatic insufficiency, no significant change was observed between 4 and 168 months. In children with pancreatic insufficiency, enzyme activity was low. In animals, elastase II and chymotrypsin activities were maximal at birth, decreased with age, and probably were associated with the digestion of milk protein. In contrast, elastase I and trypsin activities increased markedly after weaning in connection with the intake of solid food.
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PMID:Method of measurement of pancreatic elastase II activity and postnatal development of proteases in human duodenal juice and bovine and porcine pancreatic tissue. 920 Oct 99