Format

Send to

Choose Destination
Biochim Biophys Acta. 2003 Mar 17;1620(1-3):47-53.

Theanine, gamma-glutamylethylamide, is metabolized by renal phosphate-independent glutaminase.

Author information

1
Laboratory of Nutritional Biochemistry, Department of Food Science, Faculty of Agriculture, Gifu University, 1-1 Yanagido, Japan. tsuge@cc.gifu-u.ac.jp

Abstract

The distribution of theanine-degrading activity in Wistar rats was examined and this activity was detected only in the kidney. Judging from polyacrylamide gel electrophoresis, theanine-degrading enzyme from rat kidney was purified almost to homogeneity. Theanine-degrading activity was co-purified with glutaminase activity, and the relative activity for theanine was about 85% of that for L-glutamine throughout purification. Substrate specificity of purified enzyme preparation coincided well with the data of phosphate-independent glutaminase [EC 3.5.1.2], which had been previously reported. It was very curious that gamma-glutamyl methyl and ethyl esters were more effectively hydrolyzed than theanine and L-glutamine, in view of relative activity and K(m) value. It was suggested that gamma-glutamyl moiety in theanine molecule was transferred to form gamma-glutamylglycylglycine with relative ease in the presence of glycylglycine. On the other hand, purified phosphate-dependent glutaminase did not show theanine-degrading activity at all. Thus, it was concluded that theanine was hydrolyzed by phosphate-independent glutaminase in kidney and suggested that, as for the metabolic fate of theanine, its glutamyl moiety might be transferred by means of gamma-glutamyl transpeptidase reaction to other peptides in vivo.

PMID:
12595072
[Indexed for MEDLINE]

Supplemental Content

Full text links

Icon for Elsevier Science
Loading ...
Support Center