Abortive Complexes in Dehydrogenase Reactions

Determination of Dissociation Constants of Coenzymes and Abortive Ternary Complexes with Rabbit Muscle Lactate Dehydrogenase from Fluorescence Measurements.

Studies on the mechanism of substrate interaction with rabbit muscle lactate dehydrogenase have recently been reported (1). These investigations, which were primarily kinetic in nature, indicated that nicotinamide adenine dinucleotide and reduced nicotinamide adenine dinucleotide must add to the enzyme before the binding of substrates pyruvate and L-lactate. It was also noted that ternary compl...

Supplementing Pyruvate Dehydrogenase and Alpha Ketogluterate Dehydrogenase Complexes

Studies on rates of abortive ternary complex formation of lactate dehydrogenase isozymes.

Rates of formation and dissociation of an abortive ternary complex between lactate dehydrogenase isozymes from various mammalian tissues, NADf, and pyruvate were studied utilizing stopped-flow spectrofluorometry. Formation of the complex was accompanied by a decrease in protein fluorescence at 340 rnp and a loss of lactate dehydrogenase activity. Rates of formation of an abortive lactate dehydr...

Mammalian a-Keto Acid Dehydrogenase Complexes

1. The pig heart pyruvate dehydrogenase complex was separated into lipoamide hydrogenase (&I,~ = 5.55 S) and a colorless fraction by the fractionation on a calcium phosphate gel-cellulose column in the presence of 4 M urea. Subsequently, in the presence of 0.3 M potassium iodide, the colorless fraction was fractionated into two additional components, pyruvate dehydrogenase (7.45 S) and partiall...

The reactions of nitrosyl complexes with cysteine.

The reaction kinetics of a set of ruthenium nitrosyl complexes, {(X)5MNO}n, containing different coligands X (polypyridines, NH3, EDTA, pz, and py) with cysteine (excess conditions), were studied by UV-vis spectrophotometry, using stopped-flow techniques, at an appropriate pH, in the range 3-10, and T = 25 degrees C. The selection of coligands afforded a redox-potential range from -0.3 to +0.5 ...