Aspartate Aminotransferases
Pyridoxamine
The 4-aminomethyl form of VITAMIN B 6. During transamination of amino acids, PYRIDOXAL PHOSPHATE is transiently converted into pyridoxamine phosphate.
Transaminases
Cytosol
Liver
Alanine Transaminase
Tyrosine Transaminase
An enzyme that catalyzes the conversion of L-TYROSINE and 2-oxoglutarate to 4-hydroxyphenylpyruvate and L-GLUTAMATE. It is a pyridoxal-phosphate protein. L-PHENYLALANINE is hydroxylated to L-tyrosine. The mitochondrial enzyme may be identical with ASPARTATE AMINOTRANSFERASES (EC 2.6.1.1.). Deficiency of this enzyme may cause type II Tyrosinemia (see TYROSINEMIAS). EC 2.6.1.5.
Pyridoxal Phosphate
This is the active form of VITAMIN B 6 serving as a coenzyme for synthesis of amino acids, neurotransmitters (serotonin, norepinephrine), sphingolipids, aminolevulinic acid. During transamination of amino acids, pyridoxal phosphate is transiently converted into pyridoxamine phosphate (PYRIDOXAMINE).
Aspartate Carbamoyltransferase
Aspartic Acid
Substrate Cycling
A set of opposing, nonequilibrium reactions catalyzed by different enzymes which act simultaneously, with at least one of the reactions driven by ATP hydrolysis. The results of the cycle are that ATP energy is depleted, heat is produced and no net substrate-to-product conversion is achieved. Examples of substrate cycling are cycling of gluconeogenesis and glycolysis pathways and cycling of the triglycerides and fatty acid pathways. Rates of substrate cycling may be increased many-fold in association with hypermetabolic states resulting from severe burns, cold exposure, hyperthyroidism, or acute exercise.
Phenylpyruvic Acids
Tryptophan Transaminase
A PYRIDOXAL PHOSPHATE containing enzyme that catalyzes the transfer amino group from L-TRYPTOPHAN to 2-oxoglutarate in order to generate indolepyruvate and L-GLUTAMATE.
Leucine Transaminase
A PYRIDOXAL PHOSPHATE containing enzyme that catalyzes the reversible transamination of branched-chain AMINO ACIDS to 2-oxoglutarate.