Showing papers on "Methylglyoxal published in 1970"

The formation and catabolism of methylglyoxal during glycolysis

Abstract: Methylglyoxal was once believed to be involved in glucose catabolism as a component of the so-called non-phosphorylating glycolysis [ 1 ]. When phospho. rylated compounds were identified as intermediates in glucose breakdown the formation of methylglyoxal was considered to be due to non-enzymic side-reactions and thus of little or no importance [2]. In this paper we show that E. coil contains enzymes which convert dihydroxyacetone phosphate (DHAP) to pyruvate via methylglyoxal and D-lactate. This sequence provides a by-pass of the normal glycolytic reactions for the con- version of DHAP to pyruvate and as such represents a combination of the phosphorylated and non-phos- phorylated pathways of glucose breakdown (scheme 1). 2. Materials and methods The organisms used were the E. coli K12 derivat- ives K10, [3], K1 [41, P10 [5], AA200 [61, K2.1t [4] K2.1.20 and E. coli B. Cultures were grown aerob- ically at 37 ° on minimal media [7] containing the ap- propriate carbon sources at 25 mM concentration. Cells were harvested in the late logarithmic phase of growth (approx. 0.5 mg dry wt./ml) by centrifugation at 4 °. They were resuspended in 10 mM tris-HCl buffer pH 7.4, disrupted by exposure to ultrasonic oscillations then centrifuged at 2000 g for 5 min at 4 ° and the super- natant retained. Soluble protein was measured colori- metrically [8]. For the conversion of DHAP to methylglyoxal the reaction mixture contained, in 1 ml, sodium maleate buffer pH 6.6 (25/.tmoles), DHAP (2/amoles) and E.

Further Studies on Glyoxal and Methylglyoxal in Beer

Abstract: (1970). Further Studies on Glyoxal and Methylglyoxal in Beer. Proceedings. Annual meeting - American Society of Brewing Chemists: Vol. 28, Proceedings of the Annual Meeting 1970, pp. 186-191.