NADH peroxidase: kinetic mechanism and nucleotide specificity
NADH peroxidase is a flavoprotein reductase isolated from Streptococcus faecalis which catalyzes the pyridine nucleotide dependent reduction of hydrogen peroxide to water. Initial velocity, product and dead-end inhibition studies have been performed and all support a ping-pong kinetic mechanism. Further support for the ping-pong nature of the kinetic mechanism are the hydrogen peroxide independent transhydrogenase activity of the enzyme, measured either with thio-NAD or with radiolabeled NAD (isotope exchange studies). Kinetic parameters will be presented for a number of reduced pyridine nucleotide analogs. Analogs which have been modified in the adenine ring exhibit much higher K/sub m/'s relative to their adenine analogs. NADH peroxidase catalyzes the stereo-specific removal of the 4S hydrogen of NADH and primary deuterium kinetic isotope effects have been determined for a number of these substrates with 4S-deuterated molecules. There is a strong correlation between their steady-state K/sub m/ and /sup D/V/K. Small values for /sup D/V are interpreted as supporting rate-limitation in the oxidative half-reaction. These data will be discussed in terms of a kinetic and chemical mechanism proposed for NADH peroxidase.
- Research Organization:
- Albert Einstein College of Medicine, Bronx, NY
- OSTI ID:
- 5903982
- Report Number(s):
- CONF-870644-; TRN: 87-037205
- Journal Information:
- Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States), Vol. 46:6; Conference: 78. annual meeting of the American Society of Biological Chemists conference, Philadelphia, PA, USA, 7 Jun 1987
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
DEUTERIUM
ISOTOPE EFFECTS
PEROXIDASES
BIOCHEMICAL REACTION KINETICS
ISOTOPIC EXCHANGE
NAD
NADH2
TRACER TECHNIQUES
COENZYMES
ENZYMES
HYDROGEN ISOTOPES
ISOTOPE APPLICATIONS
ISOTOPES
KINETICS
LIGHT NUCLEI
NUCLEI
NUCLEOTIDES
ODD-ODD NUCLEI
ORGANIC COMPOUNDS
OXIDOREDUCTASES
REACTION KINETICS
STABLE ISOTOPES
550201* - Biochemistry- Tracer Techniques