I. C. Gunsalus

Bio: I. C. Gunsalus is an academic researcher from New York University. The author has contributed to research in topics: Pyruvate decarboxylation & Cofactor. The author has an hindex of 2, co-authored 2 publications receiving 260 citations.

Enzymatic synthesis of citrate from pyruvate and oxalacetate.

Abstract: SOLUBLE enzyme preparations from Escherichia coli and Streptococcus faecalis catalyse the dismutation of two molecules of pyruvate to acetyl phosphate, lactate and carbon dioxide when orthophosphate is present. Acetyl phosphate was determined by Lipmann's hydroxylamine reaction1. The system is almost inactive in the absence of added diphosphopyridine nucleotide (DPN). Maximum reaction-rates require, in addition to enzyme, substrate and pyridine nucleotide, the following components: orthophosphate, magnesium ions (Mg++) or manganese ions (Mn++), diphosphothiamine, a boiled extract of yeast, and lactic dehydrogenase. Coenzyme A is required for maximum yields of acetyl phosphate. The nature of the active factor in yeast extract is unknown; but it is not coenzyme A. It is possible that the compound may be a coenzyme form of the factor of O'Kane and Gunsalus2 required for oxidative decarboxylation of pyruvate by S. faecalis cells. In the absence of orthophosphate, the reaction-rate is sharply reduced and no acetyl phosphate accumulates. The dismutation can be formulated as follows:

The path of carbon in photosynthesis. XX. The steady state.

Abstract: The separation of the phenomenon of photosynthesis in green plants into a photochemical reaction and into the light-dependent reduction of carbon dioxide is discussed, The reduction of carbon dioxide and the fate of the assimilated carbon were investigated with the help of the tracer technique (exposure of the planks to the radioactive C{sup 14}O{sub 2}) and of paper chromatography A reaction cycle is proposed in which phosphoglyceric acid is the first isolable assimilations product Analyses of the algal extracts which had assimilated radioactive carbon dioxide in a stationary condition ('steady-state' photosynthesis) for a long time provided further information concerning the proposed cycle and permitted the approximate estimation, for a number of compounds of what fraction of each compound was taking part in the cycle The earlier supposition that light influences the respiration cycle was confirmed The possibility of the assistance of {alpha}-lipoic acid, or of a related substance, in this influence and in the photosynthesis cycle, is discussed