Biomaterial Database

Active site-directed modification of tryptophanase by 3-bromopyruvate. 1985

T Honda, and M Tokushige

Tryptophanase purified from Escherichia coli B/It7-A was irreversibly inactivated by 3-bromopyruvate following pseudo-first-order kinetics. The inactivation rate for the holoenzyme tended to saturate as the concentration f bromopyruvate increased. L-Alanine and DL-3-phenylserine, potent competitive inhibitors with respect to L-tryptophan decomposition, protected the enzyme from inactivation. Titration of SH groups in the enzyme protein with 5,5'-dithiobis(2-nitrobenzoic acid) (DTNB) showed that modification of one SH group per enzyme subunit resulted in a complete inactivation. When the enzyme was subjected to bromopyruvate-modification following pretreatment with DTNB, the activity was almost completely restored upon reduction with dithiothreitol. Modification of the enzyme with bromopyruvate quenched the absorption peak near 500 nm, characteristic of a quinoidal structure formed by labilization of the alpha-proton. These results support the possibility that bromopyruvate reacts with the enzyme as an affinity labeling agent.

UI	MeSH Term	Description	Entries
D007700	Kinetics	The rate dynamics in chemical or physical systems.
D008190	Lyases	A class of enzymes that catalyze the cleavage of C-C, C-O, and C-N, and other bonds by other means than by hydrolysis or oxidation. (Enzyme Nomenclature, 1992) EC 4.	Desmolase,Desmolases,Lyase
D011773	Pyruvates	Derivatives of PYRUVIC ACID, including its salts and esters.
D002621	Chemistry	A basic science concerned with the composition, structure, and properties of matter; and the reactions that occur between substances and the associated energy exchange.
D004228	Dithionitrobenzoic Acid	A standard reagent for the determination of reactive sulfhydryl groups by absorbance measurements. It is used primarily for the determination of sulfhydryl and disulfide groups in proteins. The color produced is due to the formation of a thio anion, 3-carboxyl-4-nitrothiophenolate.	5,5'-Dithiobis(2-nitrobenzoic Acid),DTNB,Ellman's Reagent,5,5'-Dithiobis(nitrobenzoate),Acid, Dithionitrobenzoic,Ellman Reagent,Ellmans Reagent,Reagent, Ellman's
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
D000345	Affinity Labels	Analogs of those substrates or compounds which bind naturally at the active sites of proteins, enzymes, antibodies, steroids, or physiological receptors. These analogs form a stable covalent bond at the binding site, thereby acting as inhibitors of the proteins or steroids.	Affinity Labeling Reagents,Labeling Reagents, Affinity,Labels, Affinity,Reagents, Affinity Labeling
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
D013053	Spectrophotometry	The art or process of comparing photometrically the relative intensities of the light in different parts of the spectrum.
D013438	Sulfhydryl Compounds	Compounds containing the -SH radical.	Mercaptan,Mercapto Compounds,Sulfhydryl Compound,Thiol,Thiols,Mercaptans,Compound, Sulfhydryl,Compounds, Mercapto,Compounds, Sulfhydryl