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A methylglyoxal-resistant mutant of Escherichia coli B excreted glutathione into the growth medium, especially during growth on medium containing methylglyoxal. In the presence of methylglyoxal, the total amount of glutathione excreted was increased about 50-fold over that of the wild-type strain. The resistant mutant had high activities of two enzyme systems: a glutathione-forming enzyme system (consisting of gamma-glutamylcysteine synthetase and glutathione synthetase) and a glyoxalase system (consisting of glyoxalase I and glyoxalase II). Methylglyoxal resistance appeared to be due to the simultaneous increase in the activities of these two enzyme systems.

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A new nicotinamid adenine dinucleotide (NAD) kinase which synthesizes nicotinamid adenine dinucleotide phosphate (NADP) from NAD and metaphosphate was found in some microorganisms. The activity of this enzyme, designated tentatively as metaphosphate dependent NAD kinase, was detected in Acetobacter, Achromobacter, Brevibacterium, Corynebacterium and Micrococcus species, but was not detected in Escherichia, Proteus and Aerobacter species. The metaphosphate-dependent NAD kinase activity of Brevibacterium ammoniagenes IAM 1645 was not affected by culture conditions, though the adenosine-5'-triphosphate (ATP)-dependent NAD kinase activity was did. The metaphosphate-dependent NAD kinase activity from B. ammoniagenes also differed from the ATP-dependent NAD kinase activity in optimal pH of reaction and stability in heating and in freezing and thawing. Of phosphate polymers tested, the potent phosphoryl donor was metaphosphate alone, and other chain and ring phosphate polymers of different degrees of condensation were not utilized by this enzyme.

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