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)

A series of substituted benzamidines has been examined for their inhibitory activity against the human serine proteases--trypsin, thrombin, plasmin, and C1s, a subunit of the first component of complement. The inhibition constants obtained for each enzyme were correlated with physical-chemical properties of the substituent group using the quantitative structure-activity relationship approach. This analysis indicated that plasmin and C1s are very similar in their interactions with substituted benzamidines. The binding of benzamidines in both enzymes was affected by electron donation from the substituent and its hydrophobicity. Thrombin-benzamidine interaction was affected only by the hydrophobicity of the substituent. Trypsin displayed a complex interaction with substituted benzamidines, and interaction was dependent on molar refractivity and molecular weight. Certain substituents deviated significantly from the interactions predicted by the analysis. These compounds, the (m- and p-amidinophenyl)pyruvic acids, when analyzed by computer modeling, suggested that direct interaction between the substituent and the enzyme surface is important in assessing the effect of substituent groups on inhibitory activity.
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PMID:Inhibition of four human serine proteases by substituted benzamidines. 15 12

Trypsin treatment of solubilized coupling factor-latent ATPase from Mycobacterium phlei alters its subunit structure and functional properties. This coupling factor exhibits ATPase activity following trypsin treatment. Concurrently, both the ability of the enzyme to rebind to membranes depleted of coupling factor and its capacity for coupled phosphorylation are lost. The native alpha (64 000 dalton) subunit undergoes limited proteolytic digestion, and the delta (14 000 dalton) subunit is partially lost. During the course of tryptic proteolysis, the coupling factor molecule may exist in one of ten unique structural state (e.g. the native, ATPase-inactive molecule exists in the alpha alpha alpha state). Rigorous analysis of the experimental data by theoretical modeling provided information concerning the intermediate structural states leading to the fully ATPase-activated alpha" alpha" alpha" state under different conditions of trypsin treatment. The theoretical models of structure-function relationships that best-represented the experimental data predicted that the native coupling factor molecule contains three copies of the alpha (64 000 dalton) form of the alpha subunit, that the alpha" (58 000 dalton) alpha subunit species contributes maximally and the alpha' (61 000 dalton) form about half-maximally to ATPase activity, that membrane rebinding ability is proportional to the number of native alpha subunits in the enzyme, and that at least one native alpha subunit/molecule is required for full expression of coupled phosphorylation. These results indicate an essential role for the alpha subunit in the regulation of ATPase activity and in the ability of the solubilized coupling factor to rebind to depleted membranes.
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PMID:Tryptic proteolysis of coupling factor-latent ATPase from mycobacterium phlei. Theoretical modeling of structure-function relationships. 15 57

To determine the reason why the Mg2+-ATPase activity of subfragment-1 prepared with chymotrypsin was activated more by actin than that of subfragment-1 prepared with trypsin was and the reason why the former could enhance the polymerization of actin and the latter could not, we digested subfragment-1, prepared with chymotrypsin, with trypsin and examined the actin activated Mg2+-ATPase activity and the ability to polymerize actin. It was found that cleavage of the heavy chain decreased the actin activated Mg2+-ATPase activity of subfragment-1 prepared with chymotrypsin but did not affect its ability to polymerize actin. Trypsin attacked the subfragment-1 heavy chain at two sites and produced 26 K, 50 K, and 21 K fragments. From the comparison of the time course of tryptic digestion with that of the decrease in actin activation, it was deduced that cleavage of the 50 K-21 K junction was mainly responsible for the decrease in actin activation. We also measured the length and the amount of F-actin polymerized by the addition of different amounts of subfragment-1. It was found that the amount of F-actin increased with the increase in the amount of subfragment-1 added and that the length of F-actin also increased though slightly. We concluded from the results that subfragment-1 enhanced the polymerization not only by facilitating the nucleus formation but also by strengthening the bond between actin monomers in forming F-actin.
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PMID:Interaction of myosin subfragment-1 with actin. III. Effect of cleavage of the subfragment-1 heavy chain on its interaction with actin. 16 Sep 13

Trypsin- and thrombin-catalysed hydrolysis of the Nalpha-aryl-sulfonyl-L-arginine methyl esters was studied. Michaelis constants and kcat were determined. The hydrolysis of the substrates by trypsin appears to depend on the polar nature of substitutes. The thrombin- catalysed reaction was believed to be sensitive to steric effects of the introducted groups.
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PMID:[Hydrolysis of the methyl esters of the N-arylsulfonyl derivatives of L-arginine by thrombin and trypsin]. 16 7

We have examined the role of proteolytic activity in the genesis and maintenance of the transformed phenotype by growing cultures of chick embryo fibroblasts transfromed by Rous sarcoma virus either in medium containing plasminogen-free serum or in medium to which protease inhibitors were added. Alterations in morphology, adhesiveness, and hexose transport were used as markers for the transformed state. Addition of the trypsin inhibitors NPGB or Soy Bean Trypsin Inhibitor at concentrations which inhibited transformation-associated fibrinolysis restored adhesiveness and morphology to near normal, but did not affect the rate of hexose transport. Growth of Rous-infected cells in plasminogen-free medium blocked the appearance of morphological and adhesive alterations, but allowed the rate of hexose transport to increase to the transformed level. Thus we were able to separate the appearance of transformation-specific changes in morphology and adhesiveness (which apparently require fibrinolytic activity) from the increased rate of hexose transport (which is independent of fibrinolytic activity). Another trypsin inhibitor, TLCK, although it did not inhibit fibrinolysis, was very effective at restoring adhesiveness and morphology as well as hexose transport to normal. This raises the possibility that there is another, perhaps earlier, protease involved in the genesis of the transformed phenotype.
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PMID:Inhibition of protease activity in cultures of rous sarcoma virus-transformed cells: effect on the transformed phenotype. 16 81

NADH-cytochrome b5 reductase [EC 1.6.2.2] has been solubilized with Triton X-100 and purified to homogeneity from rabbit liver microsomes. The purified enzyme is essentially free of the detergent and phospholipids and exists in aqueous media as an oligomeric aggregate of about 13 S. Its monomeric molecular weight is about 33,000 and 1 mole of FAD is associated with 1 mole of the monomeric unit. The enzyme catalyzes the reductions by NADH of ferricyanide and 2,6-dichlorophenol indophenol at an activity ratio of 1 : 0.09. Although the intact form of cytochrome b5 is a poorer electron acceptor than its hydrophilic fragment for the purified flavoprotein, electron transfer from the reductase to the intact cytochrome can be markedly stimulated by detergents or phospholipids, which also cause profound enhancement of the NADH-cytochrome c reductase activity reconstituted from the reducatse and cytochrome b5. Upon digestion with trypsin [EC 3.4.21.4], the ability of the reductase to form an active NADH-cytochrome c reductase system with the intact form of cytochrome b5 and Triton X-100 is rapidly lost. This loss of the reconstitution capability can be prevented by preincubation of the reductase with phosphatidylcholine liposomes. Trypsin digestion also results in the cleavage of the reductase molecule to a protein having a molecular weight of about 25,000 and a smaller fragment. The purified flavoprotein can bind to liver microsomes, liver mitochondria, sonicated human erythrocyte ghosts, and phosphatidylcholine liposomes. The reductase solubilized directly from liver microsomes by lysosomal digestion however, is devoid of membrane-binding capacity. It is concluded that the intact form of NADH-cytochrome b5 reductase is an amphipathic protein and its hydrophobic moiety, which is removable by lysosomal digestion, is responsible for the tight binding of the reductase to microsomes and for its normal functioning in the membrane.
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PMID:Purification and properties of the intact form of NADH-cytochrome b5 reductase from rabbit liver microsomes. 17 49

Results obtained by using a reconstitution technique on the Sendai virus envelope confirm that cleavage of one of the envelope glycoproteins (GP2) is prerequisite for activation of hemolytic and cell fusion activities of Sendai virus. The cleavage of GP2 occurs even when free envelope subunits are directly treated with trypsin in the presence of detergent. Trypsin treatment, either of the reconstituted particle or of the free envelope subunits but not of the intact virion, also causes a cleavage of the largest envelope glycoprotein (GP1), suggesting that a site on GP1 sensitive to trypsin becomes exposed during solubilization and reconstitution. The latter cleavage, however, is not associated with any changes in biological activities.
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PMID:Trypsin action on the growth of Sendai virus in tissue culture cells. IV. Evidence for activation of sendai virus by cleavage of a glycoprotein. 17 21

Soluble adenylate cyclase [EC 4.6.1.1] accumulates in the culture medium of exponentially growing Bordetella pertussis (300-900 pmol of cAMP formed/min per ml of 24 hr culture supernatant). In addition, there is an extracytoplasmic adenylate cyclase which enables the intact organisms to form [32P] cAMP (adenosine 3':5'-cyclic monophosphate) from exogenous [alpha-32P] ATP (200-1200 nmol of cAMP formed/min per g wet weight of cells) and which comprises 20-45% of the total adenylate cyclase activity. In contrast, only 1.7 and 2.4% of the total cell malate dehydrogenase [EC 1.1.1.37] and alkaline phosphatase [EC 3.1.3.1], respectively, are detectable in the intact cell. Trypsin treatment of intact organisms destroys 96% of the extracytoplasmic adenylate cyclase, but does not reduce the total cell malate dehydrogenase or a small pool of intracellular adenylate cyclase. Four compartments of adenylate cyclase in B. pertussis are proposed; (A) soluble enzyme in the culture supernatant (up to 20% of the total activity); (B) enzyme associated with intact cells and measurable without cell disruption (20-45%); (C) extracytoplasmic enzyme sensitive to trypsin, but not measurable in intact cells at standard substrate concentrations (40-60%); and (D) intracellular enzyme (7-9%). In comparison with previously studied bacterial adenylate cyclases, the extracytoplasmic location appears to be unique to the B. pertussis enzyme.
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PMID:Extracytoplasmic adenylate cyclase of Bordetella pertussis. 18 May 29

Trypsin increases intracellular levels of cylic AMP (cAMP) in lymphocytes. The trypsin-induced increase in cAMP is blocked by specific trypsin inhibitors and by high concentrations of different proteins. Several proteolytic enzymes from various sources, including other pancreatic proteases, do not cause an increase in cAMP under the same experimental conditions. Immobilized trypsin induced the same increase in cAMP as does free trypsin. The trypsin-induced rise in cAMP is not due to inhibition of cAMP phosphodiesterase, but consistent activation of adenylate cyclase by trypsin could not be demonstrated. The extent of the trypsin-induced increase in intracellular cAMP correlates with the type of the lymphocyte and with the state of maturity attained by the cells. Transformed lymphocytes and nonlymphoid cells do not react at all.
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PMID:Trypsin-induced increase in intracellular cyclic AMP of lymphocytes. 18 38

Pregnenolone and progesterone concentrated in the microsomal fraction of cryptorchid mouse testis compared with mitochondria and cytosol. While the concentrating mechanisms had high capacity and low association constants the effect did not seem to be due to nonspecific solubility in the lipid components since 17-hydroxyprogesterone, dehydroepiandrosterone, androstenedione and testosterone did not show differential concentration. Also digestion with phospholipases A2 and C to the point where most of the phospholipids were specifically split, only lowered the differential binding of pregnenolone and progesterone by less than half. Trypsin had a greater effect, short digestion at 0 degrees C lowering the specific binding to 35-40% and decreasing the steroid dehydrogenases to a similar extent. The members of the mixed function oxidase system in the testis microsomes were particularly sensitive to trypsin, cytochrome P-450 and, as a consequence, 17alpha-hydroxylase and 17, 20-lyase activity being eliminated under tha same conditions while liver microsomal cytochrome P-450 was hardly affected. Bonds split by trypsin seem to play a more important role in the hydroxylase activity of testis microsomes than in the hepatic system.
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PMID:Effects of trypsin and phospholipases A2 and C on enzyme organization in testis microsomes. 18 6


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