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

The posterior stomach was isolated from each male Donryu rat and separated into two parts: the tunicae mucosa and submucosa and the tunicae muscularis and serosa. Active and inactive tissue kallikrein were measured using sandwich type enzyme linked immunosorbent assay (s-ELISA) and H-Pro-Phe-Arg-MCA to complement each other. Inactive tissue kallikrein was determined (1) by measuring total tissue kallikrein and active tissue kallikrein in trypsin-treated samples and trypsin-nontreated ones, respectively; and (2) by subtracting active tissue kallikrein from total tissue kallikrein. Although tissue kallikrein was not demonstrable in the tunicae muscularis and serosa, inactive tissue kallikrein in the tunicae mucosa and submucosa reached 79.6% with s-ELISA and 99.1% with H-Pro-Phe-Arg-MCA. Water-immersion stress significantly decreased total tissue kallikrein at Stage IV of ulcers compared with the control value (p less than 0.001 in both measuring methods). Immunohistochemical staining was made using the avidin-biotin-horseradish peroxidase complex method. Tissue kallikrein was proved to be diffusely present as the inactive type within the epithelial cells of the pits in the gastric mucosa of the normal rats. With the progress of ulcers, however, it disappeared from the cells and appeared in the intercellular space. At Stage IV, it began to disappear even from the intercellular space. Based on the previously proposed process of tissue kallikrein release into blood in man, a possible interpretation of the above findings is that inactive tissue kallikrein may serve to maintain the gastric mucosa in a normal state; and that it may be transformed into the active type with ulceration and eliminated in a form of complex with some protease inhibitor in the course of aggravation.
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PMID:[Bio- and histochemical changes of tissue kallikrein in the rat stomach after water immersion-induced gastric ulcer]. 159 73

Kinetic constants for the hydrolysis by porcine tissue beta-kallikrein B and by bovine trypsin of a number of peptides related to the sequence of kininogen (also one containing a P2 glycine residue instead of phenylalanine) and of a series of corresponding arginyl peptide esters with various apolar P2 residues have been determined under strictly comparative conditions. kcat and kcat/Km values for the hydrolysis of the Arg-Ser bonds of the peptides by trypsin are conspicuously high. kcat for the best of the peptide substrates, Ac-Phe-Arg-Ser-Val-NH2, even reaches kcat for the corresponding methyl ester, indicating rate-limiting deacylation also in the hydrolysis of a peptide bond by this enzyme. kcat/Km for the hydrolysis of the peptide esters with different nonpolar L-amino acids in P2 is remarkably constant (range 1.7), as it is for the pair of the above pentapeptides with P2 glycine or phenylalanine. kcat for the ester substrates varies fivefold, however, being greatest for the P2 glycine compounds. Obviously, an increased potential of a P2 residue for interactions with the enzyme lowers the rate of deacylation. In contrast to results obtained with chymotrypsin and pancreatic elastase, trypsin is well able to tolerate a P3 proline residue. In the hydrolysis of peptide esters, tissue kallikrein is definitely superior to trypsin. Conversely, peptide bonds are hydrolyzed less efficiently by tissue kallikrein and the acylation reaction is rate-limiting. The influence of the length of peptide substrates is similar in both enzymes and indicates an extension of the substrate recognition site from subsite S3 to at least S'3 of tissue kallikrein and the importance of a hydrogen bond between the P3 carbonyl group and Gly-216 of the enzymes. Tissue kallikrein also tolerates a P3 proline residue well. In sharp contrast to the behaviour of trypsin is the very strong influence of the P2 residue in tissue-kallikrein-catalyzed reactions. kcat/Km varies 75-fold in the series of the dipeptide esters with nonpolar L-amino acid residues in P2, a P2 glycine residue furnishing the worst and phenylalanine the best substrate, whereas this exchange in the pentapeptides changes kcat/Km as much as 730-fold. This behaviour, together with the high value of kcat/Km for Ac-Phe-Arg-OMe of 3.75 X 10(7) M-1 s-1, suggests rate-limiting binding (k1) in the hydrolysis of the best ester substrates.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Effects of secondary interactions on the kinetics of peptide and peptide ester hydrolysis by tissue kallikrein and trypsin. 364 48

1. Tissue kallikrein (TK) cleaves low molecular weight kininogen (LK) at two sites to release kallidin: site I (between Arg389 and Ser390) is a typical cleavage point for a trypsin-like enzyme whereas site II (between Met379 and Lys380) is unusual and unique to TK. In order to learn more about the structural requirements and mechanism of cleavage at site II, we studied the hydrolysis by TK of several synthetic LK fragments varying in length between 4 and 22 residues and containing either site II only or both sites I and II. 2. Blocking site I cleavage in LK fragments by substituting DArg for LArg at position 389 or omitting site I from the sequence still allowed cleavage to proceed at site II. Replacement or deletion of selected amino acid residues in these fragments demonstrated that the presence of Arg381 was essential for site II cleavage to occur whereas Pro383, Phe385 and Ser386 could be replaced with Ala without affecting binding or cleavage by TK. Ki values towards TK were determined for all LK fragments in order to compare their binding affinities to the enzyme. Short peptides containing site II only exhibited high Ki values (> or = 100 microM) whereas longer fragments containing both sites I and II had Ki values of 2-7 microM. 3. In order to bring sites I and II into close proximity spatially and thus facilitating efficient cleavage in the enzyme-substrate complex, we prepared several cyclic analogs of the longer LK fragments.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Cleavage of human kininogen fragments at Met-Lys by human tissue kallikrein. 774 84

A search for tissue kallikreins in lower vertebrates resulted in the discovery of three novel kallikreins. Tissue kallikrein was isolated from the salivary gland of the Eastern Atlantic mole, Scalopus aquaticus, and the pancreas of the Southern frog, Rana berlandieri. A prokallikrein was identified in skeletal muscle of the black sea bass, Centropristis striata. These enzymes range in molecular mass from 27 to 36 kDa and are acidic proteins with pIs between 4.2 and 5.3. Bass prokallikrein was activated by trypsin cleavage. These novel kallikreins were compared with human and rat tissue kallikreins in regard to immunoreactivity, molecular weight, isoelectric point, extinction coefficient, susceptibility to serine proteinase inhibitors and their ability to cleave low molecular weight dog kininogen to release kinin peptides.
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PMID:Tissue kallikreins in evolutionarily diverse vertebrates. 879 77

Tissue kallikrein mK1 is a serine protease involved in the generation of bioactive kinins for normal cardiac and arterial function in the mouse. In the present study, the tissue kallikrein gene Klk1, which codes for mK1, was shown to be one of the most prevalent of the Klk gene species in the uteri of adult mice, and its mRNA level was significantly higher at estrus than at diestrus. Klk1 mRNA expression was enhanced in the uteri of ovariectomized mice receiving estradiol-17beta treatment. Both endometrial epithelial and stromal cells isolated from the mice exhibited Klk1 expression at detectable levels when cultured in the presence of estradiol-17beta. mK1 was characterized using the recombinant active enzyme. mK1 had trypsin-like activity with a strong preference for Arg over Lys in the P1 position, and its activity was inhibited by typical serine protease inhibitors. Casein, gelatin, fibronectin, collagen type IV, and high-molecular-weight kininogen were degraded by mK1. The single-chain tissue-type plasminogen activator was converted to the two-chain form by mK1. In addition, mK1 degraded insulin-like growth factor binding protein-3. The present data suggest that mK1 may be implicated in the growth of uterine endometrial tissues during the proliferative phase.
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PMID:Estrogen-dependent expression of the tissue kallikrein gene (Klk1) in the mouse uterus and its implications for endometrial tissue growth. 1721 31

Rhipicephalus microplus is an important ectoparasite that is responsible for transmission of anaplasmosis and babesiosis to cattle. Tissue kallikrein inhibitors might play an important role in R. microplus eggs. In the present work, we purified and characterized, a tissue kallikrein inhibitor presents in R. microplus eggs (RmKK), a protein which contains two Kunitz domain in tandem. Purified inhibitor was confirmed by amino terminal determination and its dissociation constant (Ki) for bovine trypsin and porcine pancreatic kallikrein were 0.6 nM and 91.5 nM, respectively. Using a cDNA library from R. microplus midgut, we cloned the cDNA fragment encoding mature RmKK and expressed the protein in Pichia pastoris system. Recombinant RmKK was purified by ion exchange chromatography and presented molecular mass of 16.3 kDa by MALDI-TOF analysis. Moreover, RmKK showed a tight binding inhibition for serine proteases as bovine trypsin (Ki=0.2 nM) and porcine pancreatic kallikrein (PPK) (Ki=300 nM). We performed, for the first time, the characterization of a tissue kallikrein inhibitor presents in R. microplus eggs, which the transcript is produced in the adult female gut. BmKK seems to be the strongest PPK inhibitor among all BmTIs present in the eggs and larvae (Andreotti et al., 2001; Sasaki et al., 2004). This data suggests that BmKK may participate in the development of tick egg and larvae phase.
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PMID:RmKK, a tissue kallikrein inhibitor from Rhipicephalus microplus eggs. 2481 9

The kallikrein family comprises tissue kallikrein and 14 kallikrein-related peptidases (KLKs) recognized as a subgroup of secreted trypsin- or chymotrypsin-like serine proteases. KLKs are expressed in many cellular types where they regulate important physiological activities such as semen liquefaction, immune response, neural development, blood pressure, skin desquamation and tooth enamel formation. Tissue kallikrein, the oldest member and kinin-releasing enzyme, and KLK3/PSA, a tumor biomarker for prostate cancer are the most prominent components of the family. Additionally, other KLKs have shown an abnormal expression in neoplasia, particularly in breast cancer. Thus, increased levels of some KLKs may increase extracellular matrix degradation, invasion and metastasis; other KLKs modulate cell growth, survival and angiogenesis. On the contrary, KLKs can also inhibit angiogenesis and produce tumor suppression. However, there is a lack of knowledge on how KLKs are regulated in tumor microenvironment by molecules present at the site, namely cytokines, inflammatory mediators and growth factors. Little is known about the signaling pathways that control expression/secretion of KLKs in breast cancer, and further how activation of PAR receptors may contribute to functional activity in neoplasia. A better understanding of these molecular events will allow us to consider KLKs as relevant therapeutic targets for breast cancer.
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PMID:Overview of tissue kallikrein and kallikrein-related peptidases in breast cancer. 2988 74