Inhibition of Horse Liver Alcohol Dehydrogenase by l-3,3',5-Triiodothyronine
Year: 1969
Type: article
Abstract: Triiodothyronine has been found to inhibit horse liver alcohol dehydrogenase competitively with respect to NAD+ and NADH; the φ1 and φ'1 values are increased 10-fold in the presence of 10 µm triiodothyronine. The dissociation constant for the enzyme-inhibitor complex was determined spectrofluorometrically by competitive titration and found to be 6.7 µm. The competitive inhibition constant determined kinetically was 6.3 to 6.6 µm. The stoichiometry of binding was determined by measuring protein fluorescence quenching in the presence of triiodothyronine, and it was found that 1 mole of triiodothyronine binds per eq of liver alcohol dehydrogenase. Yonetani-Theorell plots show that triiodothyronine hinders the binding of ADP-ribose, but not that of 1,10-phenanthroline, which is known to chelate zinc in liver alcohol dehydrogenase. Evidence suggests that triiodothyronine interferes with coenzyme binding by blocking the binding site of the ADP-ribose portion of the coenzyme.
Source: Journal of Biological Chemistry
Authors: Martha J. Gilleland, Joseph D. Shore
Institution: Henry Ford Hospital
Language: English
Subfield: Molecular Biology
Domain: Life Sciences
Open Access status: hybrid
Estimated APC paid: $3,430
OpenAlex ID: W1590158586