Biomaterial Database

Transition state analogs for thiamin pyrophosphate-dependent enzymes. 1976

J A Gutowski, and G E Lienhard

Many of the transition states that are formed from thiamin pyrophosphate in enzymic reactions are expected to have structures in which the thiazolium ring of thiamin pyrophosphate has lost most of its positive charge. We have synthesized thiamin thiazolone pyrophosphate from the unphosphorylated compound. The sulphur-containing ring of thiamin thiazolone pyrophosphate is uncharged, and thus the compound resembles these transition states. In agreement with the prediction from the transition state theory of reaction rates, thiamin thiazolone pyrophosphate binds to Escherichia coli pyruvate dehydrogenase complex (EC 1.2.7.1) much more strongly than thiamin pyrophosphate itself. An upper limit for the value of the dissociation constant, calculated from the extent of inactivation of the enzyme by a low concentration of thiamin thiazolone pyrophosphate, is 5 X 10(-10) M at 3 degrees in 0.5 mM MgCl2/10 mM potassium phosphate, pH 6.6. The dissociation constant for thiamin pyrophosphate under similar conditions is about 10(-5) M. The kinetics of inactivation of pyruvate dehydrogenase complex by thiamin thiazolone pyrophosphate are first order with respect to both enzyme and thiamin thiazolone pyrophosphate; the value of the second order rate constant is 5.7 X 10(5) M-1 min-1 at 3 degrees in 0.5 mM MgCl2/10 mM potassium phosphate, pH 6.6. An analysis of the decrease in the rates of inactivation caused by thiamin pyrophosphate indicates that thiamin thiazolone pyrophosphate binds at the coenzyme sites. We have also synthesized thiamin thiothiazolone pyrophosphate and obtained very similar results with this compound.

UI	MeSH Term	Description	Entries
D007700	Kinetics	The rate dynamics in chemical or physical systems.
D008433	Mathematics	The deductive study of shape, quantity, and dependence. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)	Mathematic
D011485	Protein Binding	The process in which substances, either endogenous or exogenous, bind to proteins, peptides, enzymes, protein precursors, or allied compounds. Specific protein-binding measures are often used as assays in diagnostic assessments.	Plasma Protein Binding Capacity,Binding, Protein
D011768	Pyruvate Dehydrogenase Complex	A multienzyme complex responsible for the formation of ACETYL COENZYME A from pyruvate. The enzyme components are PYRUVATE DEHYDROGENASE (LIPOAMIDE); dihydrolipoamide acetyltransferase; and LIPOAMIDE DEHYDROGENASE. Pyruvate dehydrogenase complex is subject to three types of control: inhibited by acetyl-CoA and NADH; influenced by the energy state of the cell; and inhibited when a specific serine residue in the pyruvate decarboxylase is phosphorylated by ATP. PYRUVATE DEHYDROGENASE (LIPOAMIDE)-PHOSPHATASE catalyzes reactivation of the complex. (From Concise Encyclopedia Biochemistry and Molecular Biology, 3rd ed)	Complex, Pyruvate Dehydrogenase,Dehydrogenase Complex, Pyruvate
D004926	Escherichia coli	A species of gram-negative, facultatively anaerobic, rod-shaped bacteria (GRAM-NEGATIVE FACULTATIVELY ANAEROBIC RODS) commonly found in the lower part of the intestine of warm-blooded animals. It is usually nonpathogenic, but some strains are known to produce DIARRHEA and pyogenic infections. Pathogenic strains (virotypes) are classified by their specific pathogenic mechanisms such as toxins (ENTEROTOXIGENIC ESCHERICHIA COLI), etc.	Alkalescens-Dispar Group,Bacillus coli,Bacterium coli,Bacterium coli commune,Diffusely Adherent Escherichia coli,E coli,EAggEC,Enteroaggregative Escherichia coli,Enterococcus coli,Diffusely Adherent E. coli,Enteroaggregative E. coli,Enteroinvasive E. coli,Enteroinvasive Escherichia coli
D000469	Alkaline Phosphatase	An enzyme that catalyzes the conversion of an orthophosphoric monoester and water to an alcohol and orthophosphate. EC 3.1.3.1.
D001665	Binding Sites	The parts of a macromolecule that directly participate in its specific combination with another molecule.	Combining Site,Binding Site,Combining Sites,Site, Binding,Site, Combining,Sites, Binding,Sites, Combining
D013329	Structure-Activity Relationship	The relationship between the chemical structure of a compound and its biological or pharmacological activity. Compounds are often classed together because they have structural characteristics in common including shape, size, stereochemical arrangement, and distribution of functional groups.	Relationship, Structure-Activity,Relationships, Structure-Activity,Structure Activity Relationship,Structure-Activity Relationships
D013835	Thiamine Pyrophosphate	The coenzyme form of Vitamin B1 present in many animal tissues. It is a required intermediate in the PYRUVATE DEHYDROGENASE COMPLEX and the KETOGLUTARATE DEHYDROGENASE COMPLEX.	Cocarboxylase,Thiamine Diphosphate,Berolase,Pyrophosphate, Thiamine