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

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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)

Inactive renin comprises well over half the total renin in normal human plasma. There is a direct relationship between active and inactive renin levels in normal and hypertensive populations, but the proportion of inactive renin varies inversely with the active renin level; as much as 98% of plasma renin is inactive in patients with low renin, whereas the proportion is consistently lower (usually 20-60%) in high-renin states. Two hypertensive patients with proven renin-secreting carcinomas of non-renal origin (pancreas and ovary) had high plasma active renin (119 and 138 ng/h per ml) and the highest inactive renin levels we have ever observed (5,200 and 14,300 ng/h per ml; normal range 3-50). The proportion of inactive renin (98-99%) far exceeded that found in other patients with high active renin levels. A third hypertensive patient with a probable renin-secreting ovarian carcinoma exhibited a similar pattern. Inactive renins isolated from plasma and tumors of these patients were biochemically similar to semipurified inactive renins from normal plasma or cadaver kidney. All were bound by Cibacron Blue-agarose, were not retained by pepstatin-Sepharose, and had greater apparent molecular weights (Mr) than the corresponding active forms. Plasma and tumor inactive renins from the three patients were similar in size (Mr 52,000-54,000), whereas normal plasma inactive renin had a slightly larger Mr than that from kidney (56,000 vs. 50,000). Inactive renin from each source was activated irreversibly by trypsin and reversibly by dialysis to pH 3.3 at 4 degrees C; the reversal process followed the kinetics of a first-order reaction in each instance. The trypsin-activated inactive renins were all identical to semipurified active renal renin in terms of pH optimum (pH 5.5-6.0) and kinetics with homologous angiotensinogen (Michaelis constants, 0.8-1.3 microM) and inhibition by pepstatin or by serial dilutions of renin-specific antibody. These results indicate that a markedly elevated plasma inactive renin level distinguishes patients with ectopic renin production from other high-renin hypertensive states. The co-production of inactive and active renin by extrarenal neoplasms provides strong presumptive evidence that inactive renin is a biosynthetic precursor of active renin. The unusually high proportion of inactive renin in plasma and tumor extracts from such patients is consistent with ineffective precursor processing by neoplastic tissue, suggesting that if activation of "prorenin" is involved in the normal regulation of active renin levels it more likely occurs in the tissue of origin (e.g., kidney) than in the circulation.
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PMID:Characterization of inactive renin ("prorenin") from renin-secreting tumors of nonrenal origin. Similarity to inactive renin from kidney and normal plasma. 636 74

A method for measurement of renin concentration (PRC) in human plasma has been developed and validated experimentally and theoretically. Like most of the previous methods, the present method is based on a radioimmunoassay of angiotensin I generated during incubation of plasma with an excess of renin substrate. In the present study we used, as the substrate, sheep angiotensinogen partially purified from anephric sheep plasma by ammonium sulfate fractionation and pepstatin-aminohexyl-agarose chromatography. The advantage of using sheep substrate is that it has an exceptionally high affinity for human renin. The partially purified substrate, which contained no detectable renin activity, improved the sensitivity, allowing quantification of renin in low-renin plasma. Possible interfering influences of plasma proteins on the radioimmunoassay were eliminated by the introduction of a simple deproteinization step. For determination of total renin concentration (TRC), inactive renin was activated by exposing plasma to low pH or trypsin. Normal values of PRC and TRC after careful selection of assay conditions were 2.9 +/- 0.4 and 33.9 +/- 6.1 ng angiotensin I X ml-1 X h-1, respectively. As an illustrative example of usefulness of the assay, PRC determination of a patient with a ectopic renin-secreting tumor is presented.
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PMID:An improved method for determination of active and total renin concentration in human plasma using an excess of sheep substrate. 637 May 11

Human DNA coding for renin was identified and sequenced. The gene consisted of 10 exons corresponding to a 1500 nucleotide mRNA was broken up by long stretches of 'nonsense' DNA (introns) and spanned 12,000 base pairs. In addition, the sequence of nucleotides involved in regulation of the gene was determined by sequencing upstream. Prediction of the amino acid sequence of human preprorenin revealed likely sites of processing. This helps explain many past experimental observations. For example, the pro region contained adjacent likely cleavage sites for trypsin and pepsin and so reveals why both trypsin and pepsin can activate prorenin. The structure of human renin had features involved in its highly specific hydrolysis of the Leu10-Val11 bond unique to human angiotensinogen: in particular leucine 224 (instead of valine). Renin gene expression was studied in the mouse by quantification of both renin activity and its mRNA. Sodium depletion, captopril and spironolactone increased expression of Ren-1 in the kidney. The unusual, duplicated, mouse gene, Ren-2, which is expressed in the submandibular gland was, regulated by (dihydro)testosterone in male mice and by thyroid hormone in female mice.
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PMID:Human renin gene sequence, gene regulation and prorenin processing. 640 Mar 69

For human samples quantitation of inactive renin can be carried out by incubation with trypsin under defined conditions, followed by RIA of the activated renin. For dog samples we were unable to obtain evidence for the presence of inactive renin in the plasma by using trypsin, acid or cold to activate. Increases in angiotensin generation did occur with trypsin and acid but they both changed renin substrate such that the rate of angiotensin generation by exogenous renin was increased at pH 7.4, but not at pH 5.7; also following trypsin or acid treatment angiotensin I was cleaved from renin substrate by a plasma acid protease that normally does not cleave renin substrate in plasma. Therefore, for dog samples, it is important to demonstrate that an increase in the rate of angiotensin generation is indeed due to activation of inactive renin and not to changes in pH optimum of renin with angiotensinogen or to the effect of another enzyme.
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PMID:Quantitation of inactive renin in human and dog plasma: techniques for activation. 675 90

1. A renin-inhibitory material has been partially purified from soluble extracts of the pig kidney cortex by ammonium sulphate precipitation and diethylaminoethylcellulose (DEAE) chromatography and its properties studied. 2. It displayed competitive type kinetics. It did not inhibit cathepsin D, carboxypeptidase A, pancreatic kallikrein or trypsin. 3. Renins from dogs, rabbit and rat were inhibited, but not those from sheep or man, when assayed with pig angiotensinogen. 4. The material was inactivated by treatment with trypsin, N-ethylmaleimide or p-chloromercuribenzoate. 5. Renin-inhibitory activity was not found in plasma from peripheral blood of pigs. 6. It is concluded that the function of the renin inhibitor in the renal cortex of the pig may be restricted to the intrarenal environment.
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PMID:Properties of a renin inhibitor isolated from the pig kidney cortex. 701 9

Inactive renin was partially purified from 4.5 liters of human plasma (502-fold, specific activity 0.8 X 10(-3) Goldblatt units/mg protein) and from 207 g renal cortex (103-fold, 52 X 10(-3) Goldblatt units/mg). In contrast to active renin, inactive renin from each source bound to Cibacron blue-agarose and was unable to bind to pepstatin-Sepharose. Both plasma and renal inactive renin had weaker affinity for anion-exchange resins than the active form, both bound to concanavalin A-Sepharose and were eluted with carbohydrate, and both bound tightly to hydrophobic gels. Each substance could be isolated in a completely inactive form during small-scale pilot studies, but "spontaneous" activation did occur, to a limited degree, during large-scale purification; this was possibly due to a plasma serine protease that fractionated with inactive renin during the initial purification steps. Both plasma and renal inactive renin were activated irreversibly by trypsin. Following activation, each substance lost it ability to bind to Cibacron blue-agarose. Each could be activated fully by acidification at 4 degrees C, but this activation was reversed during subsequent incubation at higher temperature and pH. There was no evidence of acid protease activity in either preparation. Activated inactive renin from both plasma and kidney were identical to partially-purified active renal renin in terms of pH optimum (pH 5.5-6.0) and reaction kinetics (Km 0.8-1.3 microM) with homologous angiotensinogen, noncompetitive inhibition by pepstatin (ki 2.5-3.5 microM), and an identical inhibition profile by monospecific antirenin antibodies. These results suggest that inactive renin from plasma and kidney may be the same substance and that their activated forms are similar to the endogenously produced active enzyme, consistent with the possibility that inactive renin is a precursor of circulating active renin.
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PMID:Biochemical similarity of partially purified inactive renins from human plasma and kidney. 704 Feb 42

The role of tumor suppressor proteins in the development of malignancy has made the understanding of their molecular mechanisms of action of great importance. Maspin is a tumor suppressor produced by a number of cell types of epithelial origin. Exogenous recombinant maspin has been shown to block the growth, motility, and invasiveness of breast tumor cell lines in vitro and in vivo. Although belonging to the the serine proteinase inhibitor (serpin) superfamily of proteins, the molecular mechanism of maspin is currently unknown. Here we show that the reactive site loop of maspin exists in an exposed conformation that does not require activation by cofactors. The reactive site loop of maspin, however, does not act as an inhibitor of proteinases such as chymotrypsin, elastase, plasmin, thrombin, and trypsin but rather as a substrate. Maspin is also unable to inhibit tissue and urokinase type plasminogen activators. Stability studies show that maspin cannot undergo the stressed-relaxed transition typical of proteinase-inhibitory serpins, and the protein is capable of spontaneous polymerization induced by changes in pH. It is likely, therefore, that maspin is structurally more closely related to ovalbumin and angiotensinogen, and its tumor suppressor activity is independent of a latent or intrinsic trypsin-like serine proteinase-inhibitory activity.
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PMID:The tumor suppressor maspin does not undergo the stressed to relaxed transition or inhibit trypsin-like serine proteases. Evidence that maspin is not a protease inhibitory serpin. 779 87

Markers of immediate-type hypersensitivity such as histamine and tryptase were measured in the plasma of nonallergic volunteers and patients with a history of hymenoptera venom anaphylaxis. No significant differences in histamine or tryptase were found between patients and controls. Norepinephrine, an important compound involved in the control of cardiovascular functions and blood pressure, was the same in patients and nonallergic volunteers. In addition, components of the renin-angiotensin system were determined. Patients with hymenoptera venom anaphylaxis showed significantly lower plasma angiotensinogen concentrations as compared to healthy nonallergic controls (p < 0.007), whereas plasma ACE activity was the same. Likewise, the plasma levels of angiotensin I and angiotensin II were significantly reduced in patients as compared to controls (p < 0.04 and p < 0.003, respectively). These findings suggest that the renin-angiotensin system may play an important role as a counteracting factor in hymenoptera venom anaphylaxis.
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PMID:Histamine, tryptase, norepinephrine, angiotensinogen, angiotensin-converting enzyme, angiotensin I and II in plasma of patients with hymenoptera venom anaphylaxis. 791 43

1. Plasma renin activity (PRA), plasma angiotensin I concentration (ANG I), plasma angiotensinogen concentration (PAC) and the plasma levels of active, total and inactive renin (prorenin) were measured in rats with carbon tetrachloride (CCl4)-induced acute renal failure. Rats were treated with a single oral dose of CCl4 (2.5 mL/kg) and killed 1, 2, 3 and 7 days later. 2. On days 1-3 PRA, ANG I and PAC decreased and increased on day 7. Active renin fell on days 2 and 3, total renin (trypsin treatment) augmented on day 1 and diminished on day 3, prorenin and per cent prorenin increased on days 1 and 2. Angiotensin I concentration paralleled PRA and PAC. The CCl4-induced decrease in PRA was secondary to the fall in active renin and in PAC. Total renin augmented as a consequence of the elevation of prorenin. Renal function, evaluated by serum urea, serum creatinine and creatinine clearance, decreased on days 1 and 2 when PRA was low and plasma prorenin was high. 3. These data do not support the involvement of the circulating active renin-angiotensin system (RAS) in the pathophysiology of acute renal failure induced by CCl4, however, increased prorenin levels were associated with the decrease in renal function.
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PMID:Circulating levels of active, total and inactive renin (prorenin), angiotensin I and angiotensinogen in carbon tetrachloride-treated rats. 844 78

Renin activity appears to be present in low concentrations in the plasma of anephric humans but could be artifactual secondary to inadvertent activation of prorenin during specimen collection and handling or from a renin-like enzyme. We studied the effects of specimen collection, storage, different assay conditions, trypsin activation, and the renin inhibitor EMD 56133 (E Merck, Darmstadt) on plasma renin activity (PRA) in anephric man. PRA was detectable in all seven bilaterally nephrectomized (BNX) patients (0.2 +/- 0.1 ng AI/ml/hr, range 0.1-0.7) but was significantly lower than normals (2.4 +/- 0.3 ng AI/ml/hr, range 1.5-3.1, p = 0.001). PRA was not different in BNX whether blood samples were collected on ice or at room temperature and assayed immediately or whether samples were frozen and assayed several days later. Prolonged cold storage of samples and five freeze-thaw cycles over six to seven months did not significantly increase PRA in normals or anephrics. However, deliberate repeated freezing and thawing over the period of a single day increased PRA 4.1-fold in BNX and 1.6-fold in normals. Renin-like activity was also detected in BNX individuals using renin concentration determinations with either excess human or sheep angiotensinogen. The inhibition of renin activity (IC-50% = 3.16 x 10(-9) molar) by EMD 56133 was not different between BNX and normals. Thus, active renin is present in the plasma of anephric humans and does not result from the inadvertent activation of prorenin due to sample handling. Although the source of PRA in BNX is unknown, the enzyme appears functionally normal as evidenced by the dose-response to a single renin inhibitor.
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PMID:Renin and renin inhibition in anephric man. 846 18


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