title: Kinetics of myoglobin redox form stabilization by malate dehydrogenase.
abstract: This study reports the reduction of metmyoglobin (MMb) via oxidation of malate to oxaloacetate and the regeneration of reduced nicotinamide adenine dinucleotide (NADH) via malate dehydrogenase (MDH). Two experiments were conducted to evaluate a malate-MDH-NADH system as a possible mechanism for MMb reduction. In experiment 1, kinetics of MDH and MMb reduction were determined, and the results showed that increasing concentrations of oxidized nicotinamide adenine dinucleotide (NAD(+)) and l-malate also increased (p < 0.05) MMb reduction in vitro. Experiment 2 assessed the reducing activity of beef muscle extracts with different concentrations of malate and NAD(+) added. Reduction of MMb in the muscle extracts via MDH was NAD(+), malate, and extract concentration dependent (p < 0.05). A new mechanism is described for the nonspecific and specific enzymatic reduction of MMb, which supports the hypothesis that malate can replenish NADH via MDH activity in post-mortem muscle, ultimately resulting in a more functional meat color.
authors.affiliation: Department of Animal Sciences and Industry, Weber Hall, Kansas State University, 224 Weber Hall, Manhattan, Kansas 66506, USA.
authors.forename: Anand
authors.initials: A
authors.lastname: Mohan
authors.forename: S
authors.initials: S
authors.lastname: Muthukrishnan
authors.forename: Melvin C
authors.initials: MC
authors.lastname: Hunt
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Barstow
authors.forename: Terry A
authors.initials: TA
authors.lastname: Houser
mesh_terms: D000818:Animals; D002417:Cattle; D004795:Enzyme Stability; D006736:Horses; D007700:Kinetics; D008291:Malate Dehydrogenase / Q000737:chemistry*; D008293:Malates / Q000737:chemistry; D009206:Myocardium / Q000201:enzymology; D009211:Myoglobin / Q000737:chemistry*; D062907:Oxaloacetic Acid / Q000737:chemistry; D010084:Oxidation-Reduction
chemical_list: D008293:Malates; D009211:Myoglobin; D062907:Oxaloacetic Acid; C030298:malic acid; D008291:Malate Dehydrogenase