A new method of determination of hydroxamic acid by its urease inhibition and application to biochemical studies

A colorimetric method for the determination of hydroxamic acid by iodine oxidation

A new colorimetric method for the determination of hydroxamic acid is described. Hydroxamic acid was oxidized quantitatively by iodine to produce nitrous acid, which was thereafter determined according to the diazocoupling reaction. This method is sensitive to as little as 5 nmol of hydroxamic acid, and the calibration curve is linear up to 50 nmol. Using this method, acyl-CoAs were determined after conversion to hydroxamic acid by the addition of hydroxylamine. The present method is applicable to the determination of free fatty acids which are activated by acyl-CoA synthetase.

Stimulation by glutamine of the formation of N6-hydroxylysine in a cell-free extract from Aerobacter aerogenes 62-1

Glutamine may serve as an activator and/or regulator of the N6-hydroxylase (E.C. 1.14.99) of Aerobacter aerogenes 62-1. Activation and stabilization of N6-hydroxylase activity was observed both in vivo and in vitro. Growth in a glutamine-supplemented medium resulted in (1) maximum N6-hydroxylase activity at an earlier stage of growth and (2) higher N6-hydroxylase activity and continued aerobactin synthesis into stationary phase. Storage of P2 in the presence of L-glutamine (1 mM) significantly increased the lifetime of the labile N6-hydroxylase activity. Inclusion of L-glutamine in the incubation mixture typically resulted in a 2-3-fold activation of the hydroxylase activity. The stimulatory effect of glutamine was independent of and additive to the enhancement of N6-hydroxylation by the active component(s) in the supernatant, S2 fraction. Glutamic acid-gamma-semihydrazide activated slightly in the absence of glutamine but activation of the system by glutamine was decreased by this compound. Azaserine was shown to be an uncompetitive inhibitor with respect to lysine and this inhibition was not reversed by glutamine.

The use of bis(mercaptoacetato-S,O)hydroxoiron(III) complex for the determination of hydroxamates

A rapid, indirect, spectrophotometric procedure for the determination of hydroxamates, based on the competition for ferric ions of the bis(mercaptoacetato-S,O)hydroxoiron(III) complex, has been developed. The assay is remarkably free of interferences by common ions, thus rendering it useful in the quantitative determination of hydroxamates in culture fluids and crude preparations.

Treatment of infected urinary stones in rats by a new hydroxamic acid, "N-(pivaloyl)glycinohydroxamic acid

The effectiveness of a new urease inhibitor, N-(pivaloyl)glycinohydroxamic acid, in the treatment of infected urinary stones was investigated. The hydroxamic acid markedly inhibited and alkalinisation of urine and stone formation when it was administered orally to rats with urinary tract infection caused by Proteus mirabilis; its inhibitory effect was potentiated by concomitant treatment with Cephalexin. This compound may become a useful medicine for the treatment of struvite stones.