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)

The phosphinic acid isosteres of di-, tetra- and hexapeptides containing a hydrophobic amino acid side chains at the P1-P'1 positions are powerful inhibitors of Human Immunodeficiency Virus protease. Ki's ranged from 0.4 nM to 26 microM at pH 6.5 and were lower at pH 4.5. The compounds showed no activity against trypsin, weak activity against renin at pH 6.5, moderate activity against pepsin at pH 2.0 (Ki values in the microM range) and substantial activity against cathepsin D at pH 3.5 (Ki values from 9 to 300 nM).
...
PMID:Selective phosphinate transition-state analogue inhibitors of the protease of human immunodeficiency virus. 211 5

In our previous studies, we showed an in vivo stimulating effect of the extract of the rat submandibular gland on plasma inactive renin release. In this study, we evaluated the effects of the rat submandibular gland extract and of some plasma active renin stimulants on inactive renin release from rat renal cortical slices. Adult male Wistar rats (250-350g) were kept on a regular diet (Na 260mg/100g) and nephrectomized under pentobarbital anesthesia (50mg/kg, i.p.). Five thin renal cortical slices were obtained from each kidney by using a razor blade. These renal cortical slices were incubated in Earle's buffer (pH7.4, Difco) at 37 degrees C for 30 min (preincubation), then transferred into 10ml fresh Earle's buffer with or without some agents and incubated at 37 degrees C for 1 hour (experimental incubation). For each experiment, 6 groups of 5 renal cortical slices were employed. The agents used in this study were as follows: isoproterenol (10(-5)M), furosemide (50 micrograms/ml), prostaglandin E1 (10(-5)M), prostaglandin I2 (10(-5)M) and the rat submandibular gland extract (100 microliters) which was obtained after homogenation with 10 x (w/v) 0.01M pyrophosphate buffer (pH6.5) including 0.1M NaCl. One ml of samples of this Earle's buffer were withdrawn every 20 min. Active renin in the samples was assayed by the commercial RIA-kit (Dainabot), and total renin was assayed after trypsin (Worthington) treatment (30 micrograms/300 microliters sample) at 4 degrees C for 10 min. Inactive renin was determined as the difference between total renin and active renin. Active and inactive renins increased linearly in the buffer without any agents (control) during the observation period (60 min). Isoproterenol (10(-5)M) stimulated the release of active renin significantly (p less than 0.01 vs. control) but did not affect the release of inactive renin. Furosemide (50 micrograms/ml) stimulated the release of active and inactive renins significantly at 20 and 40 min (p less than 0.05 vs. control) but did not affect the release of either renin at 60 min. Both prostaglandins E1 and I2 (10(-5)M) stimulated the release of active renin significantly (p less than 0.01 vs. control) but inhibited, on the other hand, the release of inactive renin significantly (p less than 0.01 vs. control). The rat submandibular gland extract (100 microliters) did not affect the release of active renin but stimulated the release of inactive renin significantly (p less than 0.05 vs. control).(ABSTRACT TRUNCATED AT 400 WORDS)
...
PMID:[Release mechanisms of inactive renin from rat renal cortical slices: role of the submandibular gland]. 211 63

The renal and genital tracts share a common embryological origin; it is thus not surprising that tissues from both can synthesize renin. Preliminary studies showed extremely high concentrations of renin in follicular fluid (FRC) following ovarian stimulation for in-vitro fertilization. This necessitated complete revalidation of the renin assays and showed that data obtained using commercial kits were invalid. An assay protocol was developed using a 1:2 dilution of follicular fluid taken into EDTA (0.3 mol/l) and o-phenanthroline (0.05 mol/l). The assay was performed at pH 7.5 in the presence of excess exogenous (sheep) renin substrate, with incubation periods of 5, 10 and 15 min at 37 degrees C. This protocol resulted in the linear generation of angiotensin I (AI). Activation of inactive renin was performed using eightfold more trypsin than was required for plasma samples. Follicular renin substrate concentrations (FRS) were measured using the same assay methodology as used for measurement of plasma renin substrate concentrations (PRS). Storage of samples at -18 degrees C for up to 2 months was found not to affect the FRC, although repeated freeze-thaw cycles did. FRC and plasma renin concentrations (PRC) were very similar in 25 unstimulated control women, studied in the follicular phase of the menstrual cycle. Trypsin activation increased follicular total renin concentration (FTRC) more than plasma total renin concentration (PTRC) (P less than 0.0001). FRS was slightly higher than PRS (P less than 0.02). Ovarian stimulation with clomiphene citrate (CC; six women) was without effect on these parameters.(ABSTRACT TRUNCATED AT 250 WORDS)
...
PMID:Studies on the human ovarian renin-angiotensin system: optimization of assay methodology and effects of follicular stimulants. 212 77

In this paper we describe a routine method of measuring inactive renin in rat plasma. The activation was performed by trypsin, at optimal concentration and incubation conditions. The trypsin treatment formed an interfering and high-performance liquid chromatography-verified tetradecapeptide-like material, which was removed before the assay by a simple batchwise use of a cation-exchange resin. The concentration of activated inactive renin was measured by an antibody-trapping method after the addition of exogenous angiotensinogen. Angiotensinogen was added in order to compensate for the trypsin destruction of angiotensinogen and in order to measure the parameter of renin concentration. The inactive renin concentration in plasma of conscious male rats was 0.48 +/- 0.13 Goldblatt units (GU) per litre (n = 38). This corresponds to 66% (range 42-92%) of the total renin concentration. Physiological experiments in conscious rats were initiated, demonstrating that nephrectomy decreased the inactive renin concentration from 0.45 +/- 0.14 to 0.27 +/- 0.05 GU/l after 24 h (n = 21; P less than 0.01). Submandibular sialoadenectomy decreased the plasma inactive renin concentration from 0.45 +/- 0.11 to 0.34 +/- 0.06 GU/l (n = 12; P less than 0.05) after 7 days. Combined sialoadenectomy and nephrectomy decreased the plasma inactive renin concentration from 0.45 +/- 0.11 to 0.24 +/- 0.06 (n = 12; P less than 0.01).
...
PMID:Measurement of inactive renin in rat plasma: effect of nephrectomy and sialoadenectomy on the plasma concentration. 216 Apr 91

1. An in vitro experiment was carried out to compare the inhibitory effect of SQ29,852 on human renal angiotensin converting enzyme (ACE) with those of captopril, enalapril and enalaprilat. 2. SQ29,852 strongly inhibited human renal ACE; its IC50 value was 1.5 x 10(-8) M. In terms of the IC50, SQ29,852's efficacy was about 1/10 of that of captopril and 1/28 of that of enalaprilat, but it was about 14 times more potent than enalapril. 3. SQ29,852 showed no inhibitory effects on cathepsin D, urinary kallikrein, renal renin, pepsin, trypsin and chymotrypsin. Its ACE-specificity was higher than that of captopril. 4. ACE inhibition by SQ29,852 was shown to be competitive, as revealed by Lineweaver-Burk plots. The affinity of SQ29,852 to ACE was shown to be high by a Ki value of 1.2 x 10(-8) M.
...
PMID:Effect of SQ29,852, a new angiotensin converting enzyme (ACE) inhibitor with a phosphonic acid group, on the activity of angiotensin converting enzyme from human kidney. 216 61

1. Active plasma renin concentration but not total renin concentration is reduced in women with pregnancy-induced hypertension compared with normotensive pregnant women. This study was conducted to determine whether women with pregnancy-induced hypertension are able to stimulate release of active renin. 2. Active plasma renin concentration was measured as the generation of angiotensin I at physiological pH in the presence of excess renin substrate, and total renin concentration was determined in the same way after trypsin activation. Inactive plasma renin concentration was calculated as the difference between total renin and active plasma renin concentrations. 3. Resting active plasma renin concentration was significantly greater in third-trimester primigravidae compared with normotensive non-pregnant women and active plasma renin and total renin concentrations rose significantly without a fall in inactive plasma renin concentration in both groups after 2 h ambulation, suggesting increased release of active plasma renin and not conversion of circulating inactive to active renin. These responses were blunted in women taking oral contraceptives. 4. Although the active plasma renin concentration was significantly reduced in third-trimester primigravidae with pregnancy-induced hypertension, total renin concentration was not significantly different compared with normotensive women of similar gestation and in both groups 30 min 60 degrees head-up tilt increased active but not inactive plasma renin concentration. 5. These studies show that in normal pregnancy active plasma renin concentration can be stimulated to a similar extent as in non-pregnant women, despite a higher resting level. This appears to be due to increased secretion of active plasma renin rather than conversion of circulating inactive to active renin.(ABSTRACT TRUNCATED AT 250 WORDS)
...
PMID:Stimulation of active renin release in normal and hypertensive pregnancy. 217 19

Within 24 h of binephrectomy in rats, plasma prorenin (activated by trypsin) rose well above normal levels while renin disappeared. This rise in prorenin may be attributed to enhanced secretion by an unidentified extrarenal source and the lack of any renin formation from it suggests that nephrectomy abolishes any systemic "convertase" mechanism that exists for its activation. Within 48 h of adrenalectomy in rats, plasma prorenin levels dropped below normal, while renin rose sharply, suggesting enhanced activation of prorenin to renin, resulting in prorenin depletion, and/or the release of a higher proportion of renin: prorenin by the kidneys. To test for enhanced convertase activity, we crosscirculated adrenalectomized (high convertase) and nephrectomized (low convertase) rats and observed a rapid drop in prorenin with an increase in renin in their shared blood. This was also observed after mixing their bloods in vitro, without crosscirculation, indicating that renal convertase activity was in the bloodstream and not just in the kidneys. Acute nephrectomy of previously adrenalectomized rats lowered renin and raised prorenin within 15 min suggesting a rapid loss of kidney-derived convertase. These results could not be attributed to changes in renin-substrate concentration. The new renin (from activated extrarenal prorenin) was blocked by a monoclonal antibody effective against normal rat plasma renin. It also generated immunoreactive angiotensin I, indicating immunological and biological coidentity with renal renin. The blood of normal control rats did not exhibit convertase activity in vivo or in vitro. These data point to a secretory (endocrine) source of extrarenal prorenin which is stimulated by nephrectomy and to a renal prorenin convertase mechanism which is abolished by nephrectomy and stimulated by adrenalectomy. Thus, in a high renin state, active renin may arise by activation of circulating prorenin (renal and extrarenal) as well as by direct renal release.
...
PMID:New renin--angiotensin from plasma prorenin? 218 71

Human prorenin is an inactive zymogen comprising 43 amino acid residues at the amino terminus of human renin. The aim of this work was to determine why prorenin is inactive at neutral pH. Eighteen different mutant prorenins, in which positively charged residues in the propeptide were substituted with either glutamine (Gln) or lysine (Lys) residues by site-directed mutagenesis, were expressed in COS-7 cells and characterized. By replacing each of the three arginine (Arg) residues (Arg10P, Arg15P, and Arg20P) with Gln residues, partially active prorenins were produced, which exhibited significant but not full renin activity without trypsin activation. The effect of double or triple amino acid substitutions on the appearance of active prorenin was cumulative, the activity reaching about 80% in a mutant in which all the three Arg residues were replaced by Gln residues. In contrast, mutant prorenins with Lys residues substituted for the Arg residues were inactive. These results clearly indicate that the positive charges of the three Arg residues are essential for maintenance of the human prorenin in an inactive form.
...
PMID:Site-directed mutagenesis of human prorenin. Substitution of three arginine residues in the propeptide with glutamine residues yields active prorenin. 218 37

The cDNA encoding human preprorenin has been introduced into the adenovirus-transformed human kidney cell line 293. The recombinant 293 cells expressed and secreted prorenin; trypsin was used to activate the secreted prorenin to renin in vitro. The recombinant protein was purified to homogeneity by a single affinity chromatographic step. Using synthetic tetradecapeptide, the Km was 57.1 +/- 9.3 microM and the kcat was (7.48 +/- 1.57) x 10(3)/hr. Activation with trypsin resulted in a secondary cleavage between Arg53 and Leu54 generating a two chain form held together via a disulfide between Cys51 and Cys58. This secondary cleavage did not affect enzyme activity as determined by the ability of renin to degrade a synthetic tetradecapeptide substrate. Our paper demonstrates the potential for producing large quantities of renin from human kidney cells and also suggests that the use of trypsin, which has been widely used to convert prorenin to renin in vitro, causes a secondary cleavage in the renin peptide chain.
...
PMID:The purification and characterization of recombinant human renin expressed in the human kidney cell line 293. 220 48

The origin of ovarian renin and its regulation by hCG were investigated in rabbit periovulatory follicles and cultured preovulatory follicular cells. Intracellular content of renin in thecal cells was 8-fold greater than of granulosa cells. In vivo, administration of hCG increased intracellular content of renin in thecal but not granulosa cells. Similar results were obtained for cultured follicular cells, from which renin was partly released into the medium. In vitro, hCG increased intracellular renin content of thecal but not granulosa cells, without obvious effect on release. Approximately 95% of ovarian renin was inactive, but could be activated by trypsin. Thecal renin was antagonized in vitro by renin antiserum, indicating a specific renin activity. Our study establishes in the rabbit the thecal cell origin of ovarian inactive renin and demonstrates hCG regulation of its synthesis.
...
PMID:Stimulation by hCG of ovarian inactive renin synthesis in rabbit preovulatory theca cells. 220 21


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>

---