title: Interaction of tetraiodofluorescein with a modified form of aspartate transcarbamylase.
abstract: Low concentrations of the dye tetraiodofluorescein activate native aspartate transcarbamylase (aspartate carbomoyltransferase, carbomoylphosphate:L-aspartate carbomoyltransferase, EC 2.1.3.2), while high concentrations inhibit the enzyme's activity [Jacobsberg, L. B., Kantrowitz, E. R. & Lipscomb, W. N. (1975) J. Biol. Chem. 250, 9238-9249]. This dye is now shown to produce similar effects upon a modified form of aspartate transcarbamylase produced by Escherichia coli grown in a culture medium supplemented with thiouracil. Significantly, the ATP-induced activation is reduced in the modified form of the enzyme to the same extent as is the tetraiodofluorescein-induced activation. Thus, a relationship is demonstrated between the internal mechanisms by which ATP and tetraiodofluorescein activate aspartate transcarbamylase.
mesh_terms: D000255:Adenosine Triphosphate / Q000494:pharmacology; D000494:Allosteric Regulation / Q000187:drug effects; D001221:Aspartate Carbamoyltransferase / Q000096:biosynthesis / Q000378:metabolism*; D004789:Enzyme Activation / Q000187:drug effects; D004926:Escherichia coli / Q000201:enzymology; D005452:Fluoresceins / Q000494:pharmacology*; D013329:Structure-Activity Relationship; D013889:Thiouracil / Q000494:pharmacology
chemical_list: D005452:Fluoresceins; D013889:Thiouracil; D000255:Adenosine Triphosphate; D001221:Aspartate Carbamoyltransferase