Effect of ATP on purified L(+) lactate dehydrogenase from electric organ of Electrophorus electricus (L.).
L(+) lactate dehydrogenase (LDH) activity from the electric organ of Electrophorus electricus was measured in the presence of ATP in the forward (substrate lactate) and reverse (substrate pyruvate) enzymatic reactions. The I50 for ATP was first determined and then the kinetics of the reactions were investigated with either constant coenzyme (NAD or NADH) concentration and varying substrate (lactate or pyruvate) concentration, or, constant substrate and varying coenzyme concentration. The kinetic data showed that ATP inhibits LDH uncompetitively with respect to the reduced and the oxidized coenzyme. As for the substrates, ATP gives a mixed type inhibition for lactate and a noncompetitive inhibition for pyruvate.
D000255:Adenosine Triphosphate / Q000494:pharmacology*; D000818:Animals; D004557:Electric Organ / Q000201:enzymology*; D004593:Electrophorus; D007700:Kinetics; D007770:L-Lactate Dehydrogenase / Q000302:isolation & purification / Q000378:metabolism*; D013379:Substrate Specificity
D000255:Adenosine Triphosphate; D007770:L-Lactate Dehydrogenase