Showing papers on "Methylglyoxal published in 1974"
TL;DR: S-Formylglutathione rather than formate is formed from formaldehyde and reduced glutathione in the reaction catalyzed by purified formaldehyde dehydrogenase, which is not strictly NAD-specific; NADP can be used although NADP has a much higher Km value than NAD, especially at high pH values.
205 citations
TL;DR: Inhibition by the drug depends, among other things, on the nature of the aliphatic amines that can serve as stimulators of rat prostate S-adenosylmethionine decarboxylase.
Abstract: Methylglyoxal bis(guanylhydrazone) {1,1′-[(methylethanediylidene)-dinitrilo]diguanidine} is a very potent inhibitor of putrescine-activated S-adenosylmethionine decarboxylases from many different mammalian tissues, including sublines of mouse L1210 leukaemia that are resistant to the drug as well as sublines that are sensitive. The inhibition of purified rat ventral prostate S-adenosylmethionine decarboxylase is competitive with respect to the S-adenosylmethionine substrate, and is much greater in the presence than in the absence of the activator putrescine. Inhibition by the drug depends, among other things, on the nature of the aliphatic amines that can serve as stimulators of rat prostate S-adenosylmethionine decarboxylase. Effects of some congeners of methylglyoxal bis(guanylhydrazone) on the enzyme are described.
125 citations
TL;DR: The results suggest that adenosine 3',5'-monophosphate results in induction of excessively high levels of an early rate-limiting step in xylose metabolism, which may be the transport ofxylose into the cell.
Abstract: Wild-type strains of Escherichia coli K-12 accumulate toxic concentrations of methylglyoxal when grown in medium containing adenosine 3′,5′-monophosphate and either d-xylose, l-arabinose, or d-glucose-6-phosphate, independent of the presence of other carbon sources. Mutations at a locus called cxm specifically block methylglyoxal formation from xylose in the presence of adenosine 3′,5′-monophosphate. Accumulation in medium containing xylose, studied in some detail, is dependent on the ability to utilize xylose and is associated with an increased rate of xylose utilization without changes in levels of xylose isomerase. These results suggest that adenosine 3′,5′-monophosphate results in induction of excessively high levels of an early rate-limiting step in xylose metabolism. This step may be the transport of xylose into the cell. The resulting excessive rates of xylose catabolism could stimulate methylglyoxal formation by overburdening late steps in glycolysis.
95 citations
TL;DR: The amount of S-adenosyl-l-methionine decarboxylase present in rat liver was enhanced 17-fold by administration of methylglyoxal bis(guanylhydrazone),* a specific inhibitor of the enzyme.
Abstract: The amount of S-adenosyl-l-methionine decarboxylase present in rat liver was enhanced 17-fold by administration of methylglyoxal bis(guanylhydrazone),* a specific inhibitor of the enzyme. The enzyme was purified 1400-fold in 50% yield from such liver extracts by chromatography on columns of the inhibitor bound to Sepharose. The purified enzyme had no spermidine synthetase activity.
62 citations
TL;DR: Inorganic orthophosphate inhibition appeared to be more complex and was overcome in a co-operative manner by increasing dihydroxyacetone phosphate concentration, and Hill plots suggested that in the presence of inorganic orthphosphate there were three diHydroxyacet one phosphate-binding sites on the enzyme.
Abstract: Methylglyoxal synthase, which forms methylglyoxal from dihydroxyacetone phosphate, has been detected in both glucose- and succinate-grown Pseudomonas saccharophila but there was no evidence for methylglyoxal production from d-glyceraldehyde. The enzyme was purified 100-fold from glucose-grown cells and found to be very similar to Escherichia coli methylglyoxal synthase. It has a pH optimum of 8.2, a molecular weight of approximately 67000 and a Km for dihydroxyacetone phosphate of 0.09 mM. Inorganic pyrophosphate, 3-phosphoglycerate, phosphoenol-pyruvate and inorganic orthophosphate were all potent inhibitors, the first three compounds being competitive with respect to dihydroxyacetone phosphate with K1 values of 0.048 mM, 0.029 mM and 0.096 mM, respectively. Inorganic orthophosphate inhibition appeared to be more complex and was overcome in a co-operative manner by increasing dihydroxyacetone phosphate concentration. Hill plots suggested that in the presence of inorganic orthophosphate there were three dihydroxyacetone phosphate-binding sites on the enzyme.
46 citations
TL;DR: The phytohemagglutinin induced DNA synthesis in guinea pig lymph node cells was inhibited remarkably by methylglyoxal bis(guanylhydrazone) and no inhibition of DNA synthesis was observed.
Abstract: The phytohemagglutinin induced DNA synthesis in guinea pig lymph node cells was inhibited remarkably by methylglyoxal bis(guanylhydrazone). This inhibitory effect was dependent on the time of its addition to the lymph node cell culture after stimulation with phytohemagglutinin. If methylglyoxal bis(guanylhydrazone) was added 48 hr after the stimulation, no inhibition of DNA synthesis was observed. Exogenous spermidine added at an early time of cell culture reversed the inhibitory effect of methylglyoxal bis(guanylhydrazone). However, no reversion occurred when spermidine was added at a late time of the cell culture.
32 citations
TL;DR: A mechanism is proposed, which exhibits the unusual feature of alternative one- and two-substrate branches, the latter involving glutathione and methylglyoxal as the first and second substrates, and the former having their hemimercaptal adduct as the substrate.
21 citations
TL;DR: The mechanism by which a large increase in the activity of an enzyme inhibited by MGBG is produced by administration of the drug is of considerable interest particularly since MGBGs is a useful antileukaemic agent.
12 citations
1 citations