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Biomedical subjects

R A Neal

Publications and source records attributed to R A Neal.

At least 109 records · Page 6Linked to original sources
PubMed1975

An examination of octanol and octanal metabolism to octanoic acid by horse liver alcohol dehydrogenase.

The kinetics of the horse liver alcohol dehydrogenase (alcohol: NAD+ oxidoreductase EC 1.1.1.1) catalyzed metabolism of octanol and octanal to octanoic acid have been examined. On incubation of octanol with horse liver alcohol dehydrogenase in the presence of NAD+, NADH as well as octanal and octanoic acid were seen as the initial products. However, on continued incubation, the octanal concentration progressively decreased to where only negligible quantities were present in the incubation after 10 min. The production of NADH was biphasic. An initial phase was followed in about 2 min with a slower but linear rate of NADH production. The production of octanoic acid was approximately linear throughout the 10 min incubation period. Since octanal is an intermediate in the oxidation of octanol to octanoic acid, the ability of semicarbazide to inhibit the metabolism of octanol to octanoic acid was examined. At a concentration of semicarbazide which was 63 times the concentration of octanol in the incubation media, the rate of formation of octanoic acid was inhibited by only 30%. The results of these experiments suggest that in the oxidation of octanol to octanoic acid a portion of the octanal formed from octanol is not released from the enzyme but, in the presence of NAD+, is oxidized to octanoic acid.

Alcohol Oxidoreductases↗
PubMed1975

Toxicological implications of the mixed-function oxidase catalyzed metabolism of carbon disulfide.

The results of these studies have indicated that the decrease in the activity of the hepatic mixed-function oxidase enzyme system and the concentration of cytochrome P-450 seen on incubation of carbon disulfide (CS2) with rat liver microsomes in the presence of NADPH is the result of the binding of the sulfur atom released in the mixed-function oxidase catalyzed metabolism of CS2 to carbonyl sulfide (COS). Moreover, it appears that COS is further metabolized by the mixed-function oxidase enzyme system to CO2 and that, analogous to the metabolism of CS2 to COS, the sulfur atom released in this reaction also binds to the microsomes and inhibits benzphetamine metabolism and decreases the concentration of cytochrome P-450 detectable as its carbon monoxide complex. The results of these studies also suggest that the decrease in the concentration of cytochrome P-450 and the liver damage seen on in vivo administration of CS2 to phenobarbital pretreated rats, is due to the mixed-function oxidase catalyzed release and binding of the sulfur atoms of CS2. The decrease in the concentration of cytochrome P-450 seen on incubation of CS2 with rat liver microsomes in the presence of NADPH does not appear to be the result of destruction of the heme group or its dissociation from the apoenzyme since the total amount of protoheme is unchanged in microsomes which have been incubated with CS2 and NADPH as compared to those not incubated with these compounds.

Animals↗