A comparative study of the influence of oxygen on lactate dehydrogenase

• Published in: Comparative biochemistry and physiology. B, Comparative biochemistry Vol. 47; no. 1; pp. 1 - 7
• Main Authors: Baeyens, d.A., Hoffert, J.Russell, Fromm, P.O.
• Format: Journal Article
• Language: English
• Published: England Elsevier Inc 15.01.1974
• Subjects: Animals; Anura; Brain - drug effects; Brain - enzymology; Canis familiaris; Dogs; Electrophoresis, Disc; Isoenzymes; Kinetics; L-Lactate Dehydrogenase - metabolism; LDH; Liver - drug effects; Liver - enzymology; Nitrogen - pharmacology; Organ Specificity; Oxygen - pharmacology; Oxygen toxicity; Rana pipiens; retina; Retina - drug effects; Retina - enzymology; Salmo gairdneri; Salmonidae; Species Specificity; Spectrophotometry, Ultraviolet; LDH; Rana pipiens; Salmo gairdneri; Canis familiaris; Oxygen toxicity; retina
• ISSN: 0305-0491
• DOI: 10.1016/0305-0491(74)90085-6

1. 1. Homogenates of retina, liver and brain tissue from trout, frogs and dogs were exposed to hyperbaric tensions of oxygen and nitrogen for 24 hr and then assayed for lactate dehydrogenase (LDH) activity. 2. 2. With the exception of trout retina all tissue preparations exhibited a lower LDH activity when exposed to hyperbaric oxygen. In general, the electrophoretic obilities of the various LDH isozymes were not altered by exposure to high oxygen thus the decrease in enzyme activity could not be associated with changes in tertiary structure or intermolecular disulfide bridge formation. 3. 3. It is hypothesized that the observed decreased LDH activity is caused by oxygen affecting the active and/or allosteric site on the enzyme. 4. 4. Apparently there is some protective mechanism which prevents inactivation of teleost retinal LDH upon exposure to hyperbaric oxygen tensions. 5. 5. Mammalian hepatic, retinal and brain tissue demonstrated altered LDH kinetics after oxygen treatment. Increased K m values signified a decreased affinity of the enzyme for substrate resulting in a decreased rate of product formation after oxygen exposure. 6. 6. Analyses of data for LDH activity in the teleost retina according to the “Michaelis-Menten constant” indicated that the enhanced enzyme activity in the oxygen exposed tissue was related to an increase in the affinity of the enzyme for substrate (i.e. decrease in K m value).