Regional Distribution of Methionine Adenosyltransferase in Rat Brain as Measured by a Rapid Radiochemical Method

Abstract

The distribution of methionine adenosyltransferase (MAT) in the CNS of the rat was studied by use of a rapid, sensitive and specific radiochemical method. The S-adenosyl-[methyl-14C]L-methionine ([14C]SAM) generated by adenosyl transfer from ATP to [methyl-14C]L-methionine is quantitated by use of a SAM-consuming transmethylation reaction. Catechol O-methyltransferase (COMT), prepared from rat liver, transfers the methyl-14C group of SAM to 3,4-dihydroxybenzoic acid. The 14C-labelled methylation products, vanillic acid and isovanillic acid, are separated from unreacted methionine by solvent extraction and quantitated by liquid scintillation counting. Compared to other methods of MAT determination, which include separation of generated SAM from methionine by ion-exchange chromatography, the assay described exhibited the same high degree of specificity and sensitivity but proved to be less time consuming. MAT activity was found to be uniformly distributed between various brain regions and the pituitary gland of adult male rats. In the pineal gland the enzyme activity is about tenfold higher.

Brain tumor protein synthesis and histological grades: A study by positron emission tomography (PET) with C11-L-Methionine

“…This small part represents a very low activity of brain tissue during our protocol examination time (46 minutes). These transmethylated active derivates can be neglected in comparison with the high activity rapidly found in newly synthetised protein compartment after injection of 11 C (Me)-L-MET (21,22).…”

Effects of Thyroxine on Methionine Adenosyltransferase Activity in Rat Cerebral Cortex and Cerebellum During Postnatal Development

“…In the rat, the tissue distribution of methionine adenosyltransferase (MAT) and the differences in enzyme activity during brain maturation have been reported (Eloranta, 1977). MAT activity was much higher in the pineal gland than in the whole brain (Guchhait and Grau, 1978), and the distribution of enzyme activity in nine brain regions was found to be uniform (Hiemke and Ghraf, 1981).…”