Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0027960 (mole)
 21,279 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Dilute solutions in cold dry ethyl acetate of 98-100% pure specimens of each of the four stereoisomers of soman were tested against enzymes in hen brain homogenate at 37 degrees and pH 8.0. Rate constants for progressive inhibition of acetylcholinesterase were 10(7)-10(8)/mole/min for both P(-) isomers and less than 10(5) for both P(+) isomers. All isomers inhibited neuropathy target esterase non-progressively to some degree. Rate constants for progressive inhibition of neuropathy target esterase were 2.7-3.8 X 10(5)/mole/min for C(-) P(+) and 2-6 X 10(4) for the others. Forced reactivation by KF was 90% initially and aging was slow in each case. Spontaneous reactivation of inhibited neuropathy target esterase was substantial during 18 hr for both P(-) isomers but not for P(+). By comparison of rate constants for the two enzymes we predict that pure P(+) isomers may cause delayed neuropathy in hens dosed at about unprotected LD50: prophylaxis and therapy against acute cholinergic effects would have to raise LD50 1000-fold before birds could tolerate potentially neuropathic doses of P(-) isomers.
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PMID:Interaction of the four stereoisomers of soman (pinacolyl methylphosphonofluoridate) with acetylcholinesterase and neuropathy target esterase of hen brain. 400 9

A method has been developed for the histochemical demonstration of phospholipase B (lysolecithinase) of rat tissues. The enzyme attacks lysolecithin with liberation of 1 mole of glycerylphosphorylcholine and 1 mole of fatty acid. The recommended procedure involves use of 6-10 micro frozen sections, fixed in cold calcium-formol and incubated at 37 degrees C in Tris buffered medium at pH 6.6 containing 2.2 X 10(-3) M lysolecithin and 1% cobalt acetate. The fatty acid liberated by enzymatic hydrolysis is trapped as a cobalt precipitate and is then converted to a black-brown precipitate by treatment with dilute ammonium sulfide in cold isotonic saline. Equivalent amounts of fatty acid and glycerylphosphorylcholine are recovered by extraction and analysis of the incubated sections and of the incubation medium, thus proving that lysolecithin hydrolysis occurs under the proposed reaction conditions. Staining is reduced by treating the sections with copper ions, mercury compounds, alcohols, acetone and by heating at 60 degrees C prior to incubation with substrate. Lowering of the pH of the incubation medium has similar effect. These findings are interpreted as evidence of the enzymatic nature of the reaction. Cells exhibiting a positive staining are found in the lamina propria of the intestinal villi and crypts, in the red pulp of the spleen and in the interstitial tissue of lung, liver and thymus. Similar elements are present in bone marrow smears and in leukocyte preparations obtained by peritoneal lavage. The morphologic and staining characteristics of these cells correspond to those of the eosinophilic leukocytes. Physical and chemical agents (x-irradiation, corticosteroids) which sharply decrease the number of eosinophils also reduce the number of cells shown histochemically to hydrolyze lysolecithin. A correspondent diminution of phospholipase B activity of homogenates of the same tissues can be shown in vitro. Differences in tissue distribution and chemical properties distinguish the phospholipase B from less specific esterases and lipases.
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PMID:Histochemical demonstration of phospholipase B (lysolecithinase) activity in rat tissues. 1712 89