Biomaterial Database

Apoenzyme content of serum aminotransferases in relation to plasma pyridoxal-5'-phosphate concentration. 1983

L W Westerhuis, and J C Hafkenscheid

To investigate the considerable variation in stimulation of serum aminotransferase activities by pyridoxal-5'-phosphate added in vitro, we determined the pyridoxal-5'-phosphate content of plasma, using the tyrosine decarboxylase reaction together with the catalytic activities of alanine aminotransferase and aspartate aminotransferase, with and without pyridoxal-5'-phosphate supplementation, within a group of normal human individuals. We found a very significant inverse linear relationship between plasma pyridoxal-5'-phosphate concentration and stimulation of the activities of these enzymes in serum after supplementation with pyridoxal-5'-phosphate. We conclude that the degree of stimulation of the apoenzyme of the two serum aminotransferases clearly depends on the pyridoxal-5'-phosphate concentration in vivo.

UI	MeSH Term	Description	Entries
D011732	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).	Pyridoxal 5-Phosphate,Pyridoxal-P,Phosphate, Pyridoxal,Pyridoxal 5 Phosphate,Pyridoxal P
D000637	Transaminases	A subclass of enzymes of the transferase class that catalyze the transfer of an amino group from a donor (generally an amino acid) to an acceptor (generally a 2-keto acid). Most of these enzymes are pyridoxyl phosphate proteins. (Dorland, 28th ed) EC 2.6.1.	Aminotransferase,Aminotransferases,Transaminase
D001051	Apoenzymes	The protein components of enzyme complexes (HOLOENZYMES). An apoenzyme is the holoenzyme minus any cofactors (ENZYME COFACTORS) or prosthetic groups required for the enzymatic function.	Apoenzyme
D001059	Apoproteins	The protein components of a number of complexes, such as enzymes (APOENZYMES), ferritin (APOFERRITINS), or lipoproteins (APOLIPOPROTEINS).	Apoprotein
D013268	Stimulation, Chemical	The increase in a measurable parameter of a PHYSIOLOGICAL PROCESS, including cellular, microbial, and plant; immunological, cardiovascular, respiratory, reproductive, urinary, digestive, neural, musculoskeletal, ocular, and skin physiological processes; or METABOLIC PROCESS, including enzymatic and other pharmacological processes, by a drug or other chemical.	Chemical Stimulation,Chemical Stimulations,Stimulations, Chemical
D014445	Tyrosine Decarboxylase	A pyridoxal-phosphate protein that catalyzes the conversion of L-tyrosine to tyramine and carbon dioxide. The bacterial enzyme also acts on 3-hydroxytyrosine and, more slowly, on 3-hydroxyphenylalanine. (From Enzyme Nomenclature, 1992) EC 4.1.1.25.	Decarboxylase, Tyrosine