Pyridine-Nucleotide Transhydrogenase. 5. Kinetic Studies on Transhydrogenase from Azotobacter vinelandii

Pyridine Nucleotide Transhydrogenase

established unequivocally that either a hydrogen or electron transfer was involved in this reaction. The possibility of a transfer of the monoester phosphate group or an exchange of reduced and oxidized nicotinamidecontaining moieties (nucleoside, nucleotide, etc.) was ruled out by this and other experiments. There still remained, however, the problem of distinguishing experimentally between th...

Pyridine nucleotide transhydrogenase from Chromatium.

The isolation and purification of a soluble transhydrogenase from Chromatium is described. The enzyme promotes the oxidation of reduced triphosphopyridine nucleotide by diphosphopyridine nucleotide. However, it will also use several analogues of DPN and TPN which include deamino-DPN, deamino-TPN, thionicotinamide DPN, and deamino-DPNH. Nicotinamide mononucleotide was also reduced. The enzyme do...

The kinetic mechanism of pyridine nucleotide transhydrogenase from Escherichia coli.

Pyridine nucleotide transhydrogenase was extracted from the membrane fraction of Escherichia coli with Triton X-100 and purified i’l-fold by chromatography on DEAE-cellulose and Sepharose 4B in buffers containing detergent. The kinetic mechanism for reduction of I-acetylpyridine adenine dinucleotide (AcPyAD) by NADPH was determined. Plots of reciprocal velocity versus the reciprocal concentrati...

Pyridine nucleotide transhydrogenase in normal human and leukemic leukocytes.

Pyridine Nucleotide Transhydrogenase VIII. PROPERTIES OF THE TRANSHYDROGENASE REACTIONS OF AN ENZYME COMPLEX ISOLATED FROM BEEF HEART MITOCHONDRIA*

Extensive studies in this and other laboratories have demonstrated the occurrence of pyridine nucleotide transhydrogenase activity in a variety of animal mitochondria (l-6), bacterial extracts (7), mitochondrial particles (8-IO), and plant tissues (11). With the introduction of the pyridine nucleotide analogues (5) the study of the true transhydrogenase reaction was greatly facilitated. This re...