Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.4.21.4 (trypsin)
 42,187 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Treatment of submitochondrial particles (ETP) with trypsin at 0 degrees destroyed NADPH leads to NAD (or 3-acetylpyridine adenine dinucleotide, AcPyAD) transhydrogenase activity. NADH oxidase activity was unaffected; NADPH oxidase and NADH leads to AcPyAD transhydrogenase activities were diminished by less than 10%. When ETP was incubated with trypsin at 30 degrees, NADPH leads to NAD transhydrogenase activity was rapidly lost, NADPH oxidase activity was slowly destroyed, but NADH oxidase activity remained intact. The reduction pattern by NADPH, NADPH + NAD, and NADH of chromophores absorbing at 475 minus 510 nm (flavin and iron-sulfur centers) in complex I (NADH-ubiquinone reductase) or ETP treated with trypsin at 0 degrees also indicated specific destruction of transhydrogenase activity. The sensitivity of the NADPH leads to NAD transhydrogenase reaction to trypsin suggested the involvement of susceptible arginyl residues in the enzyme. Arginyl residues are considered to be positively charged binding sites for anionic substrates and ligands in many enzymes. Treatment of ETP with the specific arginine-binding reagent, butanedione, inhibited transhydrogenation from NADPH leads to NAD (or AcPyAD). It had no effect on NADH oxidation, and inhibited NADPH oxidation and NADH leads to AcPyAD transhydrogenation by only 10 to 15% even after 30 to 60 min incubation of ETP with butanedione. The inhibition of NADPH leads to NAD transhydrogenation was diminished considerably when butanedione was added to ETP in the presence of NAD or NADP. When both NAD and NADP were present, the butanedione effect was completely abolished, thus suggesting the possible presence of arginyl residues at the nucleotide binding site of the NADPH leads to NAD transhydrogenase enzyme. Under conditions that transhydrogenation from NADPH to NAD was completely inhibited by trypsin or butanedione, NADPH oxidation rate was larger than or equal to 220 nmol min-1 mg-1 ETP protein at pH 6.0 and 30 degrees. The above results establish that in the respiratory chain of beef-heart mitochondria NADH oxidation, NADPH oxidation, and NADPH leads to NAD transhydrogenation are independent reactions.
J Biol Chem 1975 Dec 25
PMID:Oxidation of NADPH by submitochondrial particles from beef heart in complete absence of transhydrogenase activity from NADPH to NAD. 0 Mar 95

A virus, which was isolated from kids (Capra hircus) affected with a relatively severe generalized infection, was found to contain DNA and to have a buoyant density of 1.2820 g/cm3. The virus was sensitive to the action of lipid solvents and trypsin and was rapidly inactivated at pH 3.0 and at temperatures of 50 and 56 C. The virion, an icosahedron consisting of a nucleoid surrounded by a double membrane, measured approximately 135 nm in diameter. On the basis of its chemical and physical properties, the virus is considered a herpesvirus.
Am J Vet Res 1975 Dec
PMID:Characterization of a caprine herpesvirus. 0 Sep 33

From a crude extract of chick peas (Cicer arietinum L.) inhibitors of trypsin and chymotrypsin were isolated by affinity chromatography on a column of trypsin-Sepharose 6B. The content of inhibitors was found to be 1.5 g/kg. They were further separated into six isoinhibitors by ion-exchange chromatography on DEAE-Sephadex A-25. Two of the isoinhibitors accounted for about 50% of the isolated inhibitors and were further purified to a homogeneous state. The isoinhibitors had a molecular weight of about 10000 as determined by molecular-sieve chromatography on Sephadex G-75. They were stable towards extremes of pH and temperatures up to 75 degrees C or towards digestion by pepsin. They were also stable in 6 M urea but not in 6 M guanidine-HCl. The intact inhibitors were destroyed when the peas were cooked at 100 degrees C or when they were toasted at 130 degrees C. The four major inhibitors had similar amino acid compositions and did not contain detectable amounts of free sulfhydryl groups, tryptophan or carbohydrate. Cysteine is the dominant amino acid residue in all of them and accounted for about 20% of their amino acid content. The isoelectric point of the isoinhibitors lies in the range of pH 4.9-8.6 and two of the major inhibitors had isoelectric points of pH 4.75 and pH 4.96. They inhibited chymotrypsin to the same extent but differed in their inhibitory activities towards trypsin, indicating that they are mixtures of native and trypsinmodified forms and that they probably have separate sites for the two enzymes. They did not inhibit other proteolytic enzymes belonging to two groups (i.e., serine or cysteine enzymes) or originating from different sources (i.e., animals, plants or bacteria).
Eur J Biochem 1975 Dec 01
PMID:The trypsin and chymotrypsin inhibitors in chick peas (Cicer arietinum L.). Purification and properties of the inhibitors. 0 Dec 66

A low molecular weight active fragment of potato proteinase inhibitor IIPB was obtained by incubating the inhibitor with an equimolar amount of trypsin [EC 3.4.21.4] at pH 8 and 30 degrees for 16 hr, followed by gel filtration through Sephadex G-50, treatment with trichloroacetic acid, and CM-cellulose chromatography. The purified active fragment consisted of a single peptide chain with a molecular weight of 4,300, comprising 39 amino acid residues. It retained very strong inhibitory activity against chymotrypsin [EC 3.4.21.1] and subtilisin [EC 3.4.21.14]. However, the yield of this active fragment was rather low and was variable. On further incubation with trypsin, it was converted into smaller inactive peptides.
J Biochem 1975 Dec
PMID:Isolation of a low molecular weight active fragment of potato proteinase inhibitor IIb. 0 22

Demetallized concanavalin A is degraded rapidly at pH 7.0 and 8.2 by alpha-chymotrypsin, thermolysin or trypsin, yielding peptide fragments devoid of ability to bind to Sephadex G-75. Addition of Ni2+ and of Ca2+ confers on concanavalin A high resistance towards proteolytic attack so that even after long periods of exposure to the enzymes, almost all of the saccharide-binding capacity is preserved. Ni2+ alone protects strongly at pH 7.0 but not at pH 8.2. Apparently, both the transition metal ion and Ca2+ play an important role in stabilizing the native conformation of the protein molecule. Digestion of demetallized concanavalin A with alpha-chymotrypsin or thermolysin readily yields small peptide fragments (Mr less than 10 000), while trypsin yields as the major product(s) larger peptide(s) (Mr approximately 20 000) of appreciable resistance to further fragmentation.
Biochim Biophys Acta 1976 Dec 22
PMID:Effect of divalent metal ions on the digestibility of concanavalin A by endopeptidases. 1 27

The active site of porcine enteropeptidase (EC 3.4.21.9) was investigated in order to characterize better both catalytic and binding sites. The participation of a serine and a histidine residue in the catalytic process was fully confirmed and the two residues were located on the light chain of the enzyme. The binding site was found to be composed of at least 2 subsites S1 and S2. The subsite S1 (similar to the trypsin-binding site) is responsible for the interactions with the small substrates of trypsin and the lysine side chain of trypsinogen, while subsite S2 (probably a cluster of lysines) is responsible for the interactions with the polyanionic sequence found in all trypsinogens. Binding of substrate by subsite S2 led to an increased efficiency of the catalytic site which can be correlated to the known high specificity of enteropeptidase.
Biochim Biophys Acta 1976 Dec 08
PMID:On the catalytic and binding sites of porcine enteropeptidase. 1 10

The reactive site peptide bond of the eggplant inhibitor against trypsin [EC 3.4.21.4] was identified by chemical modifications with 1,2-cyclohexanedione, 2,4,6-trinitrobenzenesulfonic acid, acetic anhydride and glyoxal, and by sequential treatments with trypsin and carboxypeptidase B [EC 3.4.12.3]. The inhibitor was significantly inactivated by chemical modifications of arginine residues, but was not affected by lysine modifications. Free arginine was released from the trypsin-modified inhibitor by carboxypeptidase B digestion, accompanied by a marked loss of inhibitory activity. A serine residue was newly exposed at the N-terminal amino acid of the inhibitor after modification with trypsin. The reactive site of the inhibitor against trypsin was concluded to be an arginylseryl bond. The inhibitor was completely inactivated by full reduction of its disulfide bonds.
J Biochem 1976 Dec
PMID:The reactive site of eggplant trypsin inhibitor. 1 22

A dark-ground photographic technique was used to analyse the reactions of Schistosoma mansoni miracidia to homogeneous solutions of snail-conditioned water (SCW). The most significant effect of this water was to increase miracidial turning. This effect was maintained under both acid and alkaline conditions, after passage of the SCW through a mixed bed resin and after chelation of either calcium or both calcium and magnesium ions. The stimulant in the water was unaffected by trypsin but was protease-sensitive, suggesting its possible identity as a peptide. The importance of 'active spaces' rather than concentration gradients in miracidial host-location was emphasized.
Parasitology 1977 Dec
PMID:Stimulation of the activity of Schistosoma mansoni miracidia by snail-conditioned water. 2 1

We found an acid extract of normal dog kidneys to contain two distinct molecular weight forms of renin-like activity. Gel filtration chromatography showed peaks of activity as estimated molecular weights of 65,000 and 41,000. The high molecular weight fraction (HMW) comprised only 1% of the total activity of the extract. Both HMW and low molecular weight (LMW) fractions were inhibited by anti-human renin antibody and had similar broad pH-dependent activity optima between pH 6.0 and 7.5 in homologous substrate. The Michaelis constant (Km) of HMW was 3.6 times the Km of LMW. Both renins bound reversibly to concanavalin A-Sepharose with comparable affinities. HMW and LMW eluted from DEAE-Sephadex at similar salt concentrations without conversion of HMW to LMW. Transient acidification effected partial conversion of HMW to LMW without changing the total activity. Preincubation of HMW with trypsin increased the activity 40% and effected complete conversion of HMW to LMW. The apparent molecular weight difference between HMW and LMW is probably due to a covalently bound fragment(s) and not to a noncovalently bound moiety such as has been described in the rabbit and the hog. Both HMW and LMW are glycoproteins whose terminal sugar constituents possibly are similar. HMW dog renin is a new molecular form of renin that is convertible to a more active lower molecular weight renin with tryptic proteolysis.
Circ Res 1978 Dec
PMID:Chemical characteristics of a high molecular weight renin from the renal cortex of the dog. 3 May 45

1. We have found that 'acid'-activation of inactive human plasma renin is a two-phase process. About 30% of activation occurs during dialysis to pH 3.3; the remaining 70% occurs at alkaline pH. 2. The 'alkaline phase' of activation has a pH optimum between 7.5 and 8.4. It is inhibited by unacidified plasma and by soya-bean or lima-bean trypsin inhibitors. 3. 'Cryoactivation' of inactive plasma renin, which occurs at -4 degrees C and alkaline pH, is also inhibited by soya-bean or lima-bean trypsin inhibitors and by the serine protease inhibitors diisopropylphosphorofluoridate and benzamidine. 4. Thus endogenous neutral serine proteases participate in the activation of inactive plasma renin in vitro. Their action is prevented in the circulation by inhibitors which are inactivated by acid or cold.
Clin Sci Mol Med Suppl 1978 Dec
PMID:Activation of inactive plasma renin: evidence that both cryoactivation and acid-activation work by liberating a neutral serine protease from endogenous inhibitors. 3 4


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