Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: C01B12 .4
 471,332 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Four Bowman-Birk type double-headed inhibitors (B, C-II, D-II, and E-I) were isolated from soybeans. Inhibitor B was different from Bowman-Birk inhibitor only in chromatographic behavior. One mole of C-II inhibited one mole each of bovine trypsin and bovine alpha-chymotrypsin, probably at the same site, and porcine elastase at another reactive site. In the ordinary assay system D-II and E-I inhibited only trypsin activity at a non-stoichiometric inhibitor-enzyme ratio of 1:1.4, and the complexes had rather high dissociation constants. These inhibitors were all inactive toward subtilisin BPN'.
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PMID:Studies on soybean trypsin inhibitors. X. Isolation and partial characterization of four soybean double-headed proteinase inhibitors. 59 40

Three proteinase inhibitors designated as I, II, and III were isolated from the excretory gland cells of the swine kidney worm, Stephanurus dentatus. The inhibitors, which were trichloroacetic acid-soluble, were purified by affinity chromatography and ion exchange chromatography. The homogeneity of each inhibitor was shown by polyacrylamide gel electrophoresis and electrofocusing. The molecular weights of the inhibitors estimated by sodium dodecyl sulfate gel electrophoresis fell within a limited range of 9300 to 9700, and the isoelectric points were 6.45, 6.20, and 5.34 for Inhibitors I, II, and III, respectively. The inhibitors formed complexes with trypsin having apparent dissociation constants (Ki) of 2.9 X 10(-11), 7.6 X 10(-11), and 6.4 X 10(-11) M, respectively. Each inhibitor inhibits the esterolytic and proteolytic activities of both trypsin and chymotrypsin. A proteinase inhibitor present in the reproductive organs, intestines, body walls, and esophagi was identical with Inhibitor II found in the excretory gland cells. Culture medium collected after 24-h incubation with adult worms contained the same three inhibitors as the excretory gland cells. These data suggest that the gland cells may secrete the inhibitors internally and externally.
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PMID:Proteinase inhibitors from the excretory gland cells of Stephanurus dentatus. Purification and properties of three secretory proteinase inhibitors. 62 62

The syntheses are described of p-guanidino-L-phenylalanine and some of its derivatives. alpha-N-(p-Toluenesulphonyl)-p-guanidino-L-phenylalanine methyl ester is an excellent substrate of bovine trypsin (EC 3.4.21.4) (Km 57 micron; kcat. 320s-1 at pH 7.4-8.0) and a very poor substrate of human thrombin (EC 3.4.21.5) (Km 190 micron, kcat. 0.2s-1) and bovine chymotrypsin (EC 3.4.21.1). The ester inhibits thrombin clotting activity. It also inhibits the amidase and esterase activities of human thrombin, this inhibition being of the mixed type. The inhibition constant, K1, of the order of 1 micron, increases with increasing inhibitor concentration. This suggests that the enzyme binds the inhibitor at multiple sites. The importance of the residue at the P1 position [notation of Berger & Schechter (1970) Philos. Trans. R. Soc. London Ser. B 257, 249-264] in determining the selectivity of a substrate or quasi-substrate among trypsin-like enzymes is borne out. p-Guanidino-L-phenylalanine may have a use in the synthesis of selective peptide inhibitors of thrombin.
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PMID:The interaction of alpha-N-(p-toluenesulphonyl)-p-guanidino-L-phenylalanine methyl ester with thrombin and trypsin. 62 42

A radioimmunoassay for the determination of pig pancreatic kallikrein was developed. The chloramine-T method was employed for the labelling of the antigen with 125I. The assay allows the determination of kallikrein in concentrations as low as 0.4 microgram/l. Pig urinary and pig submandibular kallikreins are indistinguishable from pig pancreatic kallikrein by the assay. No cross reactivity was observed for bovine trypsin and chymotrypsin, porcine trypsin and kallikreins of guinea pig submandibular glands and guinea pig coagulation glands. Because of the high specificity of the assay, which is not attainable with conventional assays based on the enzymatic activity, the radioimmunoassay is highly suited for investigations into the physiological role and the pharmacological mechanism of action of pig glandular kallikreins.
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PMID:Development of a radioimmunoassay for pig pancreatic kallikrein. 69 May 68

When pancreatic DNase I is used as a specific biochemical reagent in the preparation of nuclear ribonucleic acids or nuclear proteins, freedom from contaminating ribonucleases or proteases is an important property of the enzyme preparation. A simple one-step procedure has been developed to effect complete removal of trypsin, chymotrypsin, and chymotrypsinogen by a combination of affinity chromatography and salting-out adsorption on lima bean protease inhibitor coupled to Sepharose (a column (0.9 X 60 cm) operated in series with a regeneratable 1-ml bed). Commercial preparations of DNase (about 10 mg) give a quantitative yield of the enzyme that is protease-free as evidenced by full stability for more than 10 days at pH 8 and 37 degrees C even in the absence of the protecting action of Ca2+. Removal of the last traces of RNase has been accomplished by affinity chromatography on a column (0.4 X 72 cm) of 5'-(4-aminophenyl-phosphoryl)-uridine 2'(3')-phosphate-Sepharose; the product is a highly active DNase that gives no detectable hydrolysis of RNA by assay on radioactive substrates.
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PMID:Preparation of protease-free and ribonuclease-free pancreatic deoxyribonuclease. 70 Dec 44

The influence of the leaving group on the reactivity of specific anilides in alpha-chymotrypsin-catalyzed hydrolysis (chymotrypsin, EC 3.4.21.2) involves both its binding to the enzyme (steric effect) and electronic nature (electronic effect). These effects are considered in terms of the stereoelectronic theory for the formation and cleavage of the tetrahedral intermediate in acyltransfer reactions. The application of this theory to the enzyme hydrolysis leads to the conclusion that the nature of the reaction products and the effectiveness of the catalysis are controlled by the orientation of the leaving group nitrogen lone pair orbital. The leaving group binding affects the formation of a reactive conformation of the enzyme tetrahedral intermediate that is presumed to intervene between the Michaelis complex and the acylenzyme. The steric and electronic effects could be separated in a straightforward fashion only in the case of equal binding of the leaving groups to the leaving-group-binding site of alpha-chymotrypsin.
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PMID:Catalysis and leaving group binding in anilide hydrolysis by chymotrypsin. 71 54

Our previous studies have shown that the two coronarodilatatory hypothalamic proteins isolated by us are not only carriers for neurohormones "K" and "C" but also procursors of coronarodilatory substances. In the present study we have looked at some physico-chemical properties of these proteins through isoelectric focusing and gel electrophoresis as well as the possibility of obtaining coronaroactive fragments by proteolytic enzymes. The results obtained have shown that the isoelectric points of the coronaroactive proteins are between pH 6.2 and 6.4. Polyacrylamide gel-electrophoresis has shown that one of the coronaroactive proteins, the carrier of neurohormone "C", moves towards the anode and is homogenous while carrier of neurohormone "K" is made up of two protein fractions. Under the action of certain enzymes (trypsin and pepsin) two coronaroactive fragments are obtained from the "neutral" protein carrier. Such an effect is not observed following the action of pronase and chymotrypsin. The physico-chemical properties of these fragments require further studies.
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PMID:[New findings concerning the coronaroactive proteins of the hypothalamus]. 80 92

Human granulocyte elastase (EC 3.4.21.-) was isolated and purified (yield = 62%, purity = 91-100%) by a new short procedure using affinity chromatography using phenylbutylamine covalently linked to Affi-Gel. The granulocyte elastase was found to have a molecular weight of 34 400 by sodium dodecyl sulphate gel electrophoresis and the molecular weight obtained from the amino acid composition was 34 970. The composition of elastase purified from normal leucocytes showed some significant differences from that of enzyme purified by others from leukemic leucocytes. The granulocyte elastase hydrolysed typical pancreatic elastase substrates like Boc-Ala-ONp and Ac-(Ala)3-Nan. The enzyme was also found to have a weak enzymatic activity in hydrolysing acetyl-L-phenylalanine-alpha-naphthyl ester, a typical chymotrypsin substrate. A monospecific antiserum raised against the purified enzyme gave a single precipitin line with the pure enzyme and also with crude granular extract, both lines being identical.
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PMID:A rapid method of purification of human granulocyte cationic neutral proteases: purification and further characterization of human granulocyte elastase. 81 Jan 68

A series of N-acetylated tetra- to heptapeptide amides has synthesized for the study of enzyme-substrate interactions beyond the S1' subsite in Streptomyces griseus Protease 3 (SGP3) and alpha-chymotrypsin (EC 3.4.21.1). Evidence was obtained that S2'-P2' enzyme-substrate interactions can play a significant role for the rate of substrate hydrolysis in both enzymes. No important interaction could be demonstrated beyond the nitrogen atom of residue P3'. This provides supplementary evidence that the active site of SGP3 extends over 6-7 subsites and that of alpha-chymotrypsin over 5-6 subsites. SGP3 is a considerably more efficient protease than alpha-chymotrypsin, kcat/Km being approximately 5-10(6) S-1-M-1 for the best substrates, thus being about 100 times higher than for alpha-chymotrypsin. However, an analysis of the kinetic data indicates that, for both enzymes, the acylation rates for the best peptide substrates approach their deacylation rates.
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PMID:The active centers of Streptomyces griseus protease 3 and alpha-chymotrypsin. Enzyme-substrate interactions beyond subsite S'1. 82 30

ATP citrate lyase was purified by two different procedures from the livers of rats first starved and then fed with a fat-deficient and high carbohydrate-glycerol diet. These enzyme preparations were judged homogeneous by sedimentation equilibrium and polyacrylamide gel electrophoresis. The molecular weight of the native enzyme was around 4.4 X 10(5) as determined by sedimentation equilibrium. On sodium dodecyl sulfate gel electrophoresis the enzyme usually showed a single protein band with an estimated molecular weight of 1.2 X 10(5). A similar value for the molecular weight of the subunit was obtained by gel filtration on 6% agarose in the presence of 6 M guanidinium chloride. The molecular weight of this polypeptide chain was estimated by sedimentation equilibrium to be around 1.1 X 10(5). These results indicated that ATP citrate lyase has a subunit structure of four polypeptides of similar size. The extinction coefficient of the dry protein and its amino acid composition are also reported. Some batches of fully active enzyme, judged to be homogeneous by sedimentation equilibrium and polyacrylamide gel electrophoresis, showed two additional major polypeptides (Mr approximately 7.1 X 10(4) and 5.5 X 10(4)) on sodium dodecyl sulfate gel electrophoresis. Studies on the polypeptides produced by proteolytic modification of the native enzyme by trypsin indicated that the additional protein bands observed on sodium dodecyl sulfate gel electrophoresis with some of the batches of enzyme could have been formed by limited proteolysis ("nicking") of the original 1.1 X 10(5) subunit. Trypsin treatment of the native enzyme did not affect the enzyme activity, whereas chymotrypsin and pronase treatment inactivated the enzyme. The trypsin-treated enzyme, which contained only the two smaller polypeptides, did not differ significantly from the untreated enzyme with respect to sedimentation behavior, phosphorylation by ATP, Km for citrate, and immunoreactivity, but it was more heat-labile than the untreated enzyme. The phosphate group on the phosphorylated "nicked" enzyme was located on the larger polypeptide fragment.
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PMID:Structure of ATP citrate lyase from rat liver. Physicochemical studies and proteolytic modification. 82 50


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