A variety of cultural conditions were examined to determine the relationship between pyruvate kinase isozyme patterns and morphology in Mucor racemosus. The results indicate that M. racemosus has two isozymes of pyruvate kinase, form A and form B, which are clearly separable on ion-exchange columns (diethylaminoethyl-cellulose). Addition of glucose to cultures growing on amino acids in air resu...

Various metabolic models have been studied by computer simulation in an effort to understand why allowing for the reversibility of the reaction catalysed by pyruvate kinase, normally considered as irreversible for all practical purposes, significantly altered the behaviour of the model of glycolysis in Trypanosoma brucei [Eisenthal, R. & Cornish-Bowden, A. (1998) J. Biol. Chem. 273, 5500-5505]....

velocities in the forward and reverse directions was 54.5: 1 , somewhat lower than that previously reported (McQuate & Utter, 1959). Product-inhibition experiments with a non-saturating concentration of the constant substrate showed that in every case competitive inhibition occurs. This is consistent with a rapidequilibrium random Bi Bi mechanism for the reverse reaction, a similar mechanism to...

The pyruvate and NADH concentrations and the buffer pH which gave maximal activity with LDH isoenzymes derived from human heart and liver tissue were established for the temperatures 25°C, 30°C, 35°C, 37°C, 40°C, 45°C, and 50°C. The velocities of the LDH isoenzymes using these maximal assay conditions were used to obtain Arrhenius plots, i.e. log initial velocity against inverse absolute temper...

It was previously shown (1) that in the cornea1 epithelium pyruvate stimulated the anaerobic oxidation of t,he C-l .of glucose. This stimulation appeared to be the result of reactions coupling the reduction of triphosphopyridme nucleotide by the dehydrogenases of the phosphogluconate oxidation pathway with the oxidation of TPNH by lactic dehydrogenase. Stimulation of the C-l oxidation of glucos...

Muscle pyruvic phosphoferase,l catalyzing the reaction PEPA + ADP a pyruvate + ATP,2 has been shown to require both Mg+ (3) and K+ or NHb+ ions (4-6) for maximum activity and to be strongly inhibited by Ca+f (4, 5). The mechanism of action of these ions is not known. The principal objective of the research reported in this paper was to acquire information about the activation by K+ ions through...

The growth of a thiamine pyrophosphate auxotroph of Escherichi coli was inhibited by either thiamine or thiamine monophosphate, and the growth of a thiamine monophosphate auxotroph was inhibited by thiamine. The thiamine pyrophosphate-dependent oxidation of pyruvate was inhibited by thiamine with whole cells of the thiamine pyrophosphate auxotroph but not with cell extracts prepared from the sa...

Addition of catalase to milk cultures of lactic streptococci resulted in increased rates of acid production, although it had no effect on cultures of lactobacilli. Milk cultures of both streptococci and lactobacilli produced detectable amounts of peroxide, which reached a maximum level in the early period of acid production followed by a drastic decrease as the acid production increased. Pyruva...

single Sep-Pak has been used for as many as 10 serum samples with no noticeable loss in efficiency. For analysis of clinical samples, I compared the above sample pretreatment procedure to the acetonitrile extraction of Kabra et al. (1). The chromatographic conditions were similar to those of Kabra et al. (1), except for our use of ambient temperature and a 3.5 mL/min flow rate. The Sep-Pak pret...