Inosinic Acid Dehydrogenase of Sarcoma 180 Cells
Year: 1968
Type: article
Abstract: Inosinic acid dehydrogenase was partially purified from sarcoma 180 cells. The concentrations of each reactant, inosine 5'-phosphate, nicotinamide adenine dinucleotide, and K+, altered both the apparent Km and Vmax values for each of the other reactants. Enzymatic activity was inhibited by both products of the reaction, xanthosine 5'-phosphate and reduced nicotinamide adenine dinucleotide; the inhibition produced by XMP was competitive with respect to IMP, whereas the inhibition caused by NADH was not competitive with respect to either IMP, NAD+, or K+. The data are consistent with an enzymatic mechanism involving ordered sequential addition of IMP, NAD+, and K+ to the enzyme to form active enzyme-substrate complexes. Substrate inhibition occurred at NAD+ concentrations several-fold higher than the optimal concentration of NAD+; the kinetics suggests that formation of an abortive ternary complex between the enzyme, XMP, and NAD+ is involved in producing this substrate inhibition.
Source: Journal of Biological Chemistry
Authors: J H Anderson, A C Sartorelli
Institution: Yale University
Language: English
Subfield: Molecular Biology
Domain: Life Sciences
Open Access status: hybrid
Estimated APC paid: $3,430
OpenAlex ID: W1484045710