title: The kinetic properties and sensitivity to pyruvate inhibition of tissue lactate dehydrogenase in diving and nondiving reptiles.
abstract: The kinetic properties and susceptibility to pyruvate inhibition of lactate dehydrogenase (LDH) were examined in three tissues of the freshwater turtle, Pseudemys scripta, and two snake species, Elaphe obsoleta and Nerodia rhombifera. Brain and heart LDH activity of the snakes surpassed that of Pseudemys at pyruvate concentrations between 0.03 and 0.50 mM. The snakes also had lower apparent Km and higher Vmax values than Pseudemys. Liver LDH activity, apparent Km, and Vmax were highest in Elaphe, and there were no differences between Km or Vmax values of Nerodia and Pseudemys. In each tissue, snake LDH was less susceptible to pyruvate inhibition than was Pseudemys LDH. The results indicate that Pseudemys LDH is no better adapted to withstand anaerobic conditions than is that of Nerodia or Elaphe.
mesh_terms: D000818:Animals; D001921:Brain / Q000201:enzymology; D004242:Diving; D007700:Kinetics; D007770:L-Lactate Dehydrogenase / Q000037:antagonists & inhibitors*; D008099:Liver / Q000201:enzymology; D009206:Myocardium / Q000201:enzymology; D011773:Pyruvates / Q000494:pharmacology*; D012104:Reptiles / Q000502:physiology*; D012911:Snakes / Q000502:physiology*; D013045:Species Specificity
chemical_list: D011773:Pyruvates; D007770:L-Lactate Dehydrogenase