Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

---

Query: EC:3.4.21.4 (trypsin)
42,187 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Activities of hydrolytic enzymes on the surface of monkey kidney, canine kidney, L. FM3A and various tumor cells were determined and compared with those in the cell homogenate. Although aminopeptidase (EC 3.4.11.-) activities were always detected on the surface membrane in mammalian cells, trypsin, chymotrypsin and elastase activities were not detected while slight glycosidase activity was detected in a suspension of cultured cells. The activities of alanine-, leucine-, methionine- and phenylalanine-aminopeptidases were rather high but aminopeptidase A, proline-, valine-, glycyl propline dipeptidyl-and glycyl propyl leucine-tripeptidyl-aminopeptidases showed relatively low activities. Aminopeptidase activity was also demonstrated in the isolated membrane fractions. The specific activities of enzymes in these membrane fractions were not significantly greater than in cell homogenate so it was concluded that these enzyme activities were rather loosely bound to the cell membrane. Further evidence for the localization of the aminopeptidase activities on the cell surface was obtained by using glass-bead-bound substrate and detecting the release of the terminal residues. When bestatin, a specific inhibitor against aminopeptidase B and leucine aminopeptidase, was included in the assay system for the enzyme activities on the cell surface, the enzymes were commonly inhibited in all types of cells.
...
PMID:Aminopeptidase activities on the surface of mammalian cells. 99 Mar 9

The membrane-bound complex of periplasmic permeases comprises two hydrophobic proteins which have been hypothesized to be integral membrane-spaninning proteins. We have investigated the topological organization of the hydrophobic components of the Salmonella typhimurium histidine permease, HisQ and HisM. Both proteins are digested by trypsin and proteinase K when either inside-out or right-side-out membrane vesicles are used. Therefore, these proteins are exposed to both surfaces of the membrane. Digestion with carboxypeptidase and binding studies with antibodies directed against the carboxyl terminus of HisQ and HisM have localized their carboxyl termini to the inside surface of the cytoplasmic membrane. Aminopeptidase digestion suggests periplasmic localization of their amino termini. Alkaline phosphatase fusions to HisQ and HisM indicate the existence of five spanners in both proteins. The periodicity and orientation of spanners and loops in HisQ and HisM match those of the five carboxyl-terminal spanners of MalF, the only other hydrophobic component of the periplasmic permeases for which topological information is available. An alignment of the sequences of all known hydrophobic components of periplasmic permeases is presented which indicates clear conservation of secondary structure and some conservation of primary sequence. The structural conservation of the components is discussed, and a role for a hydrophilic loop containing a conserved sequence (the EAA loop) is proposed.
...
PMID:Topology of the hydrophobic membrane-bound components of the histidine periplasmic permease. Comparison with other members of the family. 173 37

The activities of trypsin, aminopeptidase, and alpha-glucosidase were studied in the whole midgut, anterior and posterior midgut, and posterior midgut lumen and epithelium of the mosquito Anopheles stephensi Liston. Trypsin activity was restricted entirely to the posterior midgut lumen. No trypsin activity was found before the blood meal, but activity increased continuously up to 30 h after feeding, and subsequently returned to baseline levels by 60 h. Aminopeptidase was active in anterior and posterior midgut regions before and after feeding. In whole midguts, activity rose from a baseline of approximately 3 enzyme units (EU) per midgut to a maximum of 12 EU at 30 h after the blood meal, subsequently falling to baseline levels by 60 h. A similar cycle of activity was observed in the posterior midgut and posterior midgut lumen, whereas aminopeptidase in the posterior midgut epithelium decreased in activity during digestion. Aminopeptidase in the anterior midgut was maintained at a constant low level, showing no significant variation with time after feeding. alpha-glucosidase was active in anterior and posterior midguts before and at all times after feeding. In whole midgut homogenates, alpha-glucosidase activity increased slowly up to 18 h after the blood meal, then rose rapidly to a maximum at 30 h after the blood meal, whereas the subsequent decline in activity was less predictable. All posterior midgut activity was restricted to the posterior midgut lumen. Depending upon the time after feeding, greater than 25% of the total midgut activity of alpha-glucosidase was located in the anterior midgut. The enzyme distributions are consistent with described structural models for digestion in mosquitoes. After blood meal ingestion, proteases are active only in the posterior midgut. Trypsin is the major primary hydrolytic protease and is secreted into the posterior midgut lumen without activation in the posterior midgut epithelium. Aminopeptidase activity is also luminal in the posterior midgut, but cellular aminopeptidases are required for peptide processing in both anterior and posterior midguts. alpha-glucosidase activity is elevated in the posterior midgut after feeding in response to the blood meal, whereas activity in the anterior midgut is consistent with a nectar-processing role for this midgut region.
...
PMID:Blood digestion in the mosquito, Anopheles stephensi Liston (Diptera: Culicidae): activity and distribution of trypsin, aminopeptidase, and alpha-glucosidase in the midgut. 177 May 23

Aminopeptidase activity was partially characterized from midguts of Anopheles stephensi Liston which had been dissected 30 h after blood feeding. In crude midgut homogenate supernatants the aminopeptidases showed optimum activity at pH 8.0 and preferentially hydrolyzed alanine- and leucine-terminal amino acid substrates. Methionine, proline, lysine, and arginine terminal substrates were hydrolysed, but not glutamic acid. Activity was stimulated by Mg2+, EDTA, and low Ca2+ concentrations, while Mn2+, Tris, 1,10 phenanthroline, and higher Ca2+ concentrations were inhibitory. Supernatants from midguts homogenized in 1% Triton X-100 showed a two-fold increase in activity. Differential centrifugation of midgut homogenates demonstrated 45% of the total activity in a putative microvillar pellet and 32% in a soluble fraction. More than 92% of the total activity was solubilized after homogenization in Triton X-100. Activity in homogenate supernatants was restricted to one major peak (Mr = 552,000) with a higher molecular weight shoulder. Three distinct peaks of aminopeptidase activity were observed following Triton X-100 treatment: a minor high molecular weight peak (Mr = 552,000), and two major peaks at Mr = 123,000 and Mr = 32,000 respectively. The activity of aminopeptidase increased after a blood meal, in parallel to the post-feeding changes in trypsin activity, indicating its important role in secondary digestion of blood meal proteins.
...
PMID:Blood digestion in the mosquito, Anopheles stephensi Liston (Diptera: Culicidae): partial characterization and post-feeding activity of midgut aminopeptidases. 213 23

Aminopeptidase activity was demonstrated in the spermatozoa of the sea urchin, Strongylocentrotus intermedius. The enzyme solubilized from sperm cells was inactivated with bestatin, amastatin, p-chloromercuribenzenesulfonate, ZnCl2, and trypsin, whereas that in the intact cells was scarcely affected by these agents. On the other hand, bestatin ethyl ester inactivated the two enzyme forms to almost the same extent. It also inhibited the fertilization process in this species. These results suggest that the aminopeptidase associated with the spermatozoa is shielded with a permeable barrier and plays some role in fertilization.
...
PMID:Sea urchin sperm aminopeptidase: comparative studies of sperm-associated and -solubilized enzymes. 667 49

Aminopeptidase (AP) A, B, and M, gamma-glutamyltranspeptidase (GGT), endopeptidase I and II, membrane-associated endopeptidase I and II, dipeptidylaminopeptidase (DAP) I, II, and IV, trypsin and chymotrypsin were investigated with 4-methoxy-2-naphthylamine (MNA) substrates and ester proteinases with n-acetyl-L-methionine-1-naphthylester as substrate in the digestive tract of laboratory rodents. Biochemically, proteinases and ester proteinases show different activities in the salivary glands, esophagus, stomach, liver, pancreas, duodenum jejunum, ileum, and colon; sex differences in proteinase and ester proteinase activity were measured, especially in the submandibular gland of rats and mice. Histochemically these enzymes are preferentially localized in surface membranes, lysosomes, secretion granules, and Golgi apparatus of cells of the endocrine and exocrine secretory system, resorptive system and immune system of the digestive tract. Besides the general occurrence of lysosomal (DAP I and II, single cell types and functional units of these systems possess their own individual proteinase and ester proteinase equipment. The cells of the granulated tubules of rat and mouse submandibular gland contain endopeptidase I and ester proteinases, its acinar cells DAP IV, the chief cells of the stomach APA, enteroendocrine cells APA, APM, and DAP II, hepatocytes DAP IV or GGT and DAP IV, lymphocytes GGT and DAP IV, and enterocytes trypsin, chymotrypsin, and membrane-associated endopeptidase I and II. Sex differences in proteinase activity are most conspicuous in the granulated tubule cells of the rat and mouse submandibular gland. The data suggest that proteinases and ester proteinases are involved in specific functions of the cells of the digestive tract. Furthermore, myoepithelial cells, smooth muscle cells of the muscular layer of the stomach and intestine, connective tissue cells (including mast cells) and fibers, nerve cells of the myenteric plexus and the capillary bed of the digestive organs are equipped with some of these proteinases and with ester proteinases and show organ differences.
...
PMID:Investigation of proteinases in the digestive tract using 4-methoxy-2-naphthylamine (MNA) substrates. 701 83

The blood-digestion kinetics of Anopheles albitarsis, An. aquasalis, An. bellator and An. homunculus were determined in the laboratory using females collected from two field sites in Trinidad. Anopheles aquasalis displayed the highest rate of haemolysis (giving an absorbance of 0.36 at 410 nm), followed by An. albitarsis (0.16), An. bellator (0.07) and An. homunculus (0.05). Trypsin activity peaked 12-24 h after blood feeding and then declined to zero at 60 h in all four species. Anopheles albitarsis had significantly higher maximum trypsin activity (0.69 units) than An. aquasalis (0.28), An. bellator (0.18) or An. homunculus (0.12) (P < 0.01). Aminopeptidase activity patterns were similar for An. aquasalis, An. bellator and An. homunculus, with peak activity at 18 h. Among the An. albitarsis mosquitoes, peak aminopeptidase activity occurred at 24 h. The peritrophic membrane developed 18, 30, 30 and 36 h post-feeding in An. aquasalis, An. albitarsis, An. bellator and An. homunculus, respectively. Stage V ovarian follicles began to mature 36 h after An. albitarsis and An. bellator fed to repletion and after 48 h in An. aquasalis and An. homunculus. Ovarian development in the four species was not affected by patterns of erythrocyte haemolysis, proteolytic enzyme activity or peritrophic-membrane development. The inter- and intra-specific variations observed in the blood-processing physiology of the four species of Anopheles are briefly discussed in terms of phylogeny.
...
PMID:Blood-digestion kinetics of four Anopheles species from Trinidad, West Indies. 749 67

Aminopeptidase (AP) activity on rat natural killer (NK) cells was found to have the following characteristics: (1) the activity was surface associated and not secreted, as determined by extracellular location of product and by the cessation of hydrolysis of substrate upon removal of the cells from the medium. (2) The activity was linear with respect to time and cell number. (3) The enzymatic activity on splenocytes and on the NK leukemia cell line CRNK-16, but not on IL-2 activated NK (A-NK) cells, was sensitive to trypsin treatment. (4) The AP activity on intact cells had a broad pH dependency with optimal activity at slightly alkaline pH but lower activity at acidic pH. (5) There was a preference for neutral substrates and essentially no activity towards acidic substrates. (6) Enzymatic activity was inhibited in the presence of the AP inhibitors bestatin and amastatin, and in the presence of the chelator, 1,10 phenanthroline, indicating the involvement of a metalloprotease. (7) Culture of A-NK cells with bestatin resulted in a decrease in cytotoxicity against YAC-1 and P815 targets. Amastatin treatment caused only a slight decrease in cytotoxicity against YAC-1 targets, but a significant decrease in cytotoxicity against P815 targets. (8) Treatment of A-NK cultures with specific inhibitors of APases caused an increase in expression of CD2 (an increase from 20-80% with bestatin and an increase from 25-35% in the presence of amastatin). These results provide the first evidence for the existence of APases on the surface of NK cells and suggest a role for these enzymes in the regulation of cytotoxic activity and of CD2 surface expression.
...
PMID:Surface aminopeptidase activity of rat natural killer cells. I. Biochemical and biological properties. 816 43

Bloodmeal digestion in midguts of the sandflies Phlebotomus papatasi and Phlebotomus langeroni (Diptera: Psychodidae) was investigated in optimized assays to detect general protease, trypsin and aminopeptidase activities using synthetic substrates. Optimal activity occurred at pH 8-9 for all enzymes examined in both species. Protease activity peaked at 24-34 h post human bloodmeal in midguts of P. papatasi and 34-48 h in P. langeroni; all endo- and exoprotease activities were completed by 50 h in P. papatasi compared to 72 h in P. langeroni. Hydrolysis of two chymotrypsin substrates was < 2% of trypsin activity in both species. Aminopeptidase activity was associated mainly with the midgut wall, whereas trypsin activity was confined to the midgut lumen. A feature of digestion in P. langeroni was the high level of aminopeptidase recorded within 10 h of the bloodmeal.
...
PMID:Bloodmeal digestion in the midgut of Phlebotomus papatasi and Phlebotomus langeroni. 836 57

If proteolytic enzymes affect the innate vector competence of Anopheles mosquitoes for Plasmodium infections, then mechanistic effects should be most pronounced at the zygote to ookinete developmental transition. Anopheles freeborni, Anopheles gambiae, and Anopheles albimanus exhibit excellent, good, and poor susceptibility to P. falciparum, respectively. Aminopeptidase and trypsin activity were determined relative to the kinetics of P. falciparum ookinete development in these 3 Anopheles species. Ookinetes in A. freeborni, A. gambiae, and A. albimanus were first observed at 18 hr postinfection. For separate infection experiments, peak parasite densities were observed at either 18, 24, or 30 hr for A. albimanus, at 24 or 30 hr for A. freeborni, and at either 24, 30, or 36 hr for A. gambiae. Although the 3 species supported ookinete development equally, they had significantly different oocyst infection rates. Similar patterns of aminopeptidase activity were observed for the most susceptible species, A. freeborni, and the least susceptible species, A. albimanus. Anopheles gambiae had the lowest levels of aminopeptidase. Anopheles freeborni also had higher levels of trypsin activity than either A. albimanus or A. gambiae. Irrespective of differences in innate vector competence, the 3 species showed peak levels of aminopeptidase and trypsin that were coincident with peak ookinete densities. Thus, the close correspondence between the kinetics of ookinetes and enzymes associated with bloodmeal digestion indicates that proteolytic enzymes alone do not limit the early stages of sporogonic development in vector species of Anopheles.
...
PMID:Proteolytic enzyme activity and Plasmodium falciparum sporogonic development in three species of Anopheles mosquitoes. 862 78


1 2 Next >>

---