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Biomedical subjects

W M Jones

Publications and source records attributed to W M Jones.

At least 37 records · Page 2Linked to original sources
PubMed1977

Inactivation of bacterial D-amino acid transaminase by beta-chloro-D-alanine.

Purified D-amino acid transaminase from Bacillus sphaericus catalyzes an alpha,beta elimination from the D isomer of beta-chloroalanine to yield equivalent amounts of pyruvate, chloride, and ammonia; the L isomer of chloroalanine is not a substrate for this transaminase. During the beta elimination there is a synchronous loss in enzyme activity; the Kinact for beta-chloroalanine was estimated to be about 10 micrometers. The alpha-aminoacrylate-Schiff base intermediate formed after beta elimination of chloride ion is probably the key intermediate that partitions between one inactivation event for every 1500 turnovers. In the presence of D-alanine and alpha-ketoglutarate, which are good substrates for the transaminase activity of this enzyme, beta-chloroalanine is a potent, competitive inhibitor (K1 = 10 micrometers) with D-alanine and a weak, uncompetitive inhibitor with alpha-ketoglutarate.

Alanine↗
PubMed1977

Blood pressure effects of lower abdominal aortic surgery with particular reference to the use of morphine and droperidol in modifying the responses.

Hypertensive responses during operations on the abdominal aorta are common. We have shown that hypertensive changes occur before cross-clamping of the aorta. We have also shown that droperidol modifies the hypertensive changes in operations on the lower aorta. Although further studies are required, our preliminary results show a higher rise of serum epinephrine and norepinephrine levels in one patient receiving morphine, as compared to one patient receiving the same dose per unit body weight of morphine plus droperidol. With maintenance of adequate pre-operative hydration and intra-operative fluid and blood replacement, declamping hypotension was transient in both groups of our patients.

Adult↗
PubMed1974

Inhibition of bacterial growth by beta-chloro-D-alanine.

The D- and L-isomers of beta-chloroalanine inhibit the growth of Diplococcus pneumoniae, Streptococcus pyogenes, Bacillus subtilis, and Escherichia coli. With pneumococcus the inhibition by beta-chloro-D-alanine is completely prevented by either D-alanine or D-alanyl-D-alanine, while L-alanine is not effective in preventing the inhibition. The inhibition of growth by beta-chloro-L-alanine is not affected by D-alanine and is only partially prevented by high concentrations of L-alanine. The intracellular free alanine in untreated E. coli and B. subtilis is about 95% in the D-configuration while the free intracellular alanine in both organisms after treatment with beta-chloro-D-alanine is predominantly the L-isomer. These results suggested that the beta-chloroamino acid inactivates alanine racemase (EC 5.1.1.1). Indeed, when extracts of E. coli or B. subtilis were treated with beta-chloro-D-alanine, the activities of alanine racemase and of D-glutamate-D-alanine transaminase were found to be 90-95% inhibited. Studies with mice have shown that beta-chloro-D-alanine is an effective antibacterial agent in vivo againt D. pneumoniae, S. pyogenes, and E. coli.

Alanine↗