Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.4.24.3 (collagenase)
 18,340 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Fluxes of 86Rb+ and hydrolysis of p-nitrophenyl phosphate were measured in collagenase-isolated islets of diabetic C57BL/KsJ-db/db-mice and normal controls (C57BL/KsJ-+/+). Both types of islets accumulated Rb+ avidly, as originally reported for hand-dissected islets of non-inbred ob/ob-mice. KsJ-db/db-mouse islets showed enhanced accumulation of Rb+ and normal activity of K+-activated nitrophenyl phosphatase. D-glucose, 20 mmol/l, inhibited Rb+ efflux in normal islets but not in those from KsJ-db/db-mice. The glucose insensitivity of Rb+ efflux was observed in young animals, which exhibit glucose-induced insulin release, as well as in old animals, which do not secrete insulin in response to glucose. The anomalous regulation of Rb+ efflux already present in young animals may bear on the liability of KsJ-db/db-mouse B-cells to develop defective control of membrane potential, an abnormal metabolism of cyclic AMP, and a marked failure of insulin secretory capacity.
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PMID:86Rb+ fluxes and K+-stimulated nitrophenyl phosphatase activity in the pancreatic islets of genetically diabetic mice (C57BL/KsJ-db/db). 21 36

Isolated myocytes were prepared from adult canine hearts using a combined technique of myocardial perfusion followed by incubation with collagenase. More than 60% of the cells routinely excluded trypan blue dye. Disruption of the myocytes was accomplished using high pressure nitrogen cavitation. After differential and sucrose gradient centrifugation, the peak sarcolemmal fraction averaged 100-fold enrichment in ouabain-inhibited K+-stimulated p-nitrophenyl phosphatase and 82-fold in ouabain-inhibited (Na+,K+)-ATPase. These sarcolemmal membranes are enriched in phospholipid phosphorus (1.98 mumol/mg of protein) and more than 4-fold in sphingomyelin and cholesterol. Polyacrylamide gels revealed three major protein peaks at 50,000, 91,000, and 140,000 apparent molecular weights. This work demonstrates the feasibility of preparing highly pure cardiac sarcolemma from isolated adult myocytes. The problem of cellular cross-contamination due to heterogeneity of cell types in whole myocardial tissue has been circumvented. The level of enrichment exceeds all reported preparations of cardiac sarcolemma from whole myocardium and cultured myocytes. This preparation should prove to be useful as an in vitro model for studies of physiological, pharmacological, and pathological perturbations of sarcolemmal structure and function.
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PMID:Preparation and properties of highly enriched cardiac sarcolemma from isolated adult myocytes. 624 86

Collagenase treatment, commonly used to prepare alkaline phosphatase-rich matrix vesicles from epiphyseal cartilage growth plates, seems to affect the integrity of this membrane-bound enzyme. Alkaline phosphatase-rich rat osseous plates were incubated with 1,000 U/mL collagenase for 3 h, at 37 degrees C and after purification on Sepharose 4B, kinetic studies were performed using nitrophenylphosphate and pyrophosphate as substrates. The optimum apparent pH for the hydrolysis of p-nitrophenylphosphate and pyrophosphate increased from 9.4 to 10.25 and from 8.0 to 9.0, respectively, as a consequence ofcollagenase treatment. In the absence of Mg2+ ions, the enzyme hydrolyzed PNPP with KM = 322.5 +/- 15.3 microM and V = 965.2 +/- 45.8 U/mg, while in the presence of 2 mM Mg2+ ions, V increased 66%. Cobalt (K0.5 = 5.3 +/- 0.3 microM) and manganese (K0.5 = 0.72 +/- 0.03 microM) ions stimulated the PNPPase activity of the collagenase-treated enzyme, but with a lower apparent affinity when compared with that of not-treated enzyme. In the absence of Mg2+ ions pyrophosphate was hydrolyzed according to Michaelis-Menten kinetics (KM = 105.1 +/- 6.3 microM and V = 64.9 +/- 3.9 U/mg), but site-site interactions (nH = 1.2) were observed in the presence of 2 mM Mg2+ ions (V = 110.8 +/- 5.5 U/mg; K0.5 = 42.7 +/- 2.0 microM). To our knowledge this is the first report showing significant alterations on phosphohydrolytic activity and metal binding properties of bone alkaline phosphatase due to associated neutral proteases in collagenase preparations often used for the isolation of matrix vesicles.
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PMID:Rat osseous plate alkaline phosphatase: effect of neutral protease digestion on the hydrolysis of pyrophosphate and nitrophenylphosphate. 1248 27