Threonine Dehydratase: A pyridoxal-phosphate protein that catalyzes the deamination of THREONINE to 2-ketobutyrate and AMMONIA. The role of this enzyme can be biosynthetic or biodegradative. In the former role it supplies 2-ketobutyrate required for ISOLEUCINE biosynthesis, while in the latter it is only involved in the breakdown of threonine to supply energy. This enzyme was formerly listed as EC 220.127.116.11.L-Serine Dehydratase: A PYRIDOXAL-phosphate containing enzyme that catalyzes the dehydration and deamination of L-serine to form pyruvate. This enzyme was formerly listed as EC 18.104.22.168.Threonine: An essential amino acid occurring naturally in the L-form, which is the active form. It is found in eggs, milk, gelatin, and other proteins.Hydro-Lyases: Enzymes that catalyze the breakage of a carbon-oxygen bond leading to unsaturated products via the removal of water. EC 4.2.1.Urocanate Hydratase: An enzyme that catalyzes the conversion of 4,5-dihydro-4-oxo-5-imidazolepropanoate to urocanate and water. EC 22.214.171.124.Isoleucine: An essential branched-chain aliphatic amino acid found in many proteins. It is an isomer of LEUCINE. It is important in hemoglobin synthesis and regulation of blood sugar and energy levels.NitrosoguanidinesCorynebacterium: A genus of asporogenous bacteria that is widely distributed in nature. Its organisms appear as straight to slightly curved rods and are known to be human and animal parasites and pathogens.Propanediol Dehydratase: An enzyme that catalyzes the dehydration of 1,2-propanediol to propionaldehyde. EC 126.96.36.199.KetonesButyrates: Derivatives of BUTYRIC ACID. Included under this heading are a broad variety of acid forms, salts, esters, and amides that contain the carboxypropane structure.Prephenate Dehydratase: An enzyme that catalyzes the conversion of prephenate to phenylpyruvate with the elimination of water and carbon dioxide. In the enteric bacteria this enzyme also possesses chorismate mutase activity, thereby catalyzing the first two steps in the biosynthesis of phenylalanine. EC 188.8.131.52.Porphobilinogen Synthase: An enzyme that catalyzes the formation of porphobilinogen from two molecules of 5-aminolevulinic acid. EC 184.108.40.206.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.Culture Media: Any liquid or solid preparation made specifically for the growth, storage, or transport of microorganisms or other types of cells. The variety of media that exist allow for the culturing of specific microorganisms and cell types, such as differential media, selective media, test media, and defined media. Solid media consist of liquid media that have been solidified with an agent such as AGAR or GELATIN.