Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.4.21.7 (plasmin)
 9,023 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Two different plasma membrane enriched fractions were isolated from the homogenized rat kidney by differential centrifugation in dextran or sucrose. Marker enzymes and morphological studies indicated that one fraction (BLM) was enriched in membrane particles originating from the basolateral membrane of tubular cells, while the other, the PM fraction, contained membrane from the luminal side. Membrane-bound kallikrein and renin were found in both fractions. Kallikrein activity was enhanced by phospholipase A2, melittin and detergents. Renin activity was greatly increased after solubilization by the same agents. In addition to bound kallikrein and renin BLM contained a prekallikrein which was activated by trypsin or plasmin. BLM prekallikrein has a slower electrophoretic mobility and a higher molecular weight than urinary or glandular kallikrein. The basal membrane of tubular cells appears to contain all of the essential enzyme components of the kallikrein and renin systems. Kallikrein of the PM fraction is probably released into the urine, while prekallikrein and kallikrein from basal membrane may be the source of kallikrein in lymph and renal venous effluent. Membrane-bound renin could be a form of renin retained by the kidney.
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PMID:Prekallikrein, kallikrein and renin in membrane fractions of rat kidney. 675 83

A basolateral membrane (BLM) enriched fraction of the homogenized rat kidney contained kallikrein and prekallikrein which differ from urinary kallikrein. Triton X-100 (0.1%) or melittin (10(-7) - 10(-5)M) solubilized the membrane-bound enzyme. Prekallikrein was activated by trypsin and plasmin. Active kallikrein and activated prekallikrein cleaved the chromogenic substrate S-2266 and released bradykinin from kininogen. Aprotinin and antiserum to rat urinary kallikrein inhibited BLM kallikrein. Gel electrophoresis separated activated BLM prekallikrein and kallikrein; prekallikrein even after activation moved slower (Rf = 0.3) in electrophoresis at an alkaline pH than active kallikrein (Rf = 1). Gel filtration resolved BLM kallikrein to two proteins of low (4 X 10(4) M) and high (1.5 X 10(5) M) molecular weight. After isoelectric focusing of the activated BLM fraction, two kallikreins with pIs of 3.9 and 5.3 were obtained. The BLM fraction also contained renin which became active after Triton treatment. Renin activity was not enhanced by trypsin or acid pH indicating that there was no prorenin present. Thus, BLM of rat kidney contains a kallikrein which is different from urinary kallikrein. This kallikrein, when released from basal membrane, may appear in renal lymph and venous effluent.
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PMID:Kallikrein and prekallikrein of the isolated basolateral membrane of rat kidney. 675 27

Renin, an aspartate protease, cleaves the alpha-globulin angiotensinogen to produce the decapeptide angiotensin I, which is then converted to the vasoactive hormone angiotensin II by the action of a peptidase 'converting enzyme'. An inactive form of renin sometimes termed prorenin is present in normal human plasma. Its enzymatic activity is increased by exposure to a pH of 3.0 or 3.3 followed by dialysis towards neutral pH. Only a small proportion of the inactive renin is activated during the acid stage of dialysis, most of the activation apparently taking place during the subsequent dialysis to pH 5.7 (ref. 4) or 7.5 (ref. 5). Furthermore, if inhibitors of serine proteases are added to the plasma, the amount of inactive renin activated by this dialysis procedure is reduced. These results suggest that acid-activation is mediated by serine proteases. The role of enzymes such as plasma kallikrein, plasmin and renal kallikrein as physiological activators of inactive renin has recently been discussed. In our study of the activation of plasma inactive renin we have no found that, contrary to previous reports, complete activation of inactive renin takes place during the acid stage of dialysis. This activation can be reversed if plasma is rapidly adjusted to pH 7.4 and warmed. The next step in the acid-activation procedure, that is, dialysis to neutral pH, renders the initial acid-activation irreversible. These results were completely unexpected, and we offer an explanation that reassesses the nature of inactive renin and the activation process.
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PMID:Reversible activation-inactivation of renin in human plasma. 700 88

A 3-fold increase in active renin was found after a kidney cortex extract was incubated with plasma from either normal or nephrectomized rats (0.34 +/- 0.04 to 1.34 +/- 0.08 and 1.60 +/- 0.06 micrograms Angiotensin I/mg tissue/hr, respectively). A plasma protein that activates renal renin was purified 900-fold. Purification of the protein was achieved by a combination of ammonium sulfate fractionation, molecular filtration on Sephacryl S-200 HR and ion-exchange chromatography on Mono Q HR 5/5 associated to an fast performance liquid chromatography (FPLC) system. The protein shows a molecular weight of approximately 54,000 Da. Renin activation was not inhibited by serine protease inhibitors, such as phenylmethyl sulfonylfluoride, aprotinin, soybean trypsin inhibitor and N-tosyl-L-phenylalanine chloromethyl ketone or by the cystein protease inhibitors N-ethylmaleimide and leupeptin. By using enzyme inhibitors, it was found that the activation process is not mediated by kallikrein, plasmin, tonin, cathepsin B or trypsin-like enzymes. From these results, we conclude that there is in circulating plasma a previously unidentified enzyme capable of activating inactive kidney renin. However, the possibility that this protein acts by activating the renin-substrate reaction cannot be dismissed.
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PMID:Activation of renal renin by a protein plasma fraction: a novel enzymatic mechanism. 865 95