Twenty-four-hour changes of S-adenosylmethionine, S-adenosylhomocysteine adenosine and their metabolizing enzymes in rat liver; possible physiological significance in phospholipid methylation.
1. The metabolic control of adenosine concentration in the rat liver through the 24-hr cycle is related to the activity of adenosine-metabolizing enzymes [5'-nucleotidase (5'N), adenosine deaminase (A.D.), adenosine kinase (A.K.) and S-adenosylhomocysteine hydrolase (SAH-H)]. 2. Two peaks of adenosine were observed, one at 12:00 hr caused by high activity of 5'N and SAH-H, and the other at 02:00 hr, caused by a decrease in purine catabolism and purine utilization, low activity of SAH-H and de novo purine formation. 3. The similarity of the adenosine and S-adenosylmethionine (SAM) profiles through the 24-hr cycle suggests a role of adenosine in transmethylation reactions, because, during the night (02:00 hr), the metabolic conditions favor the formation and accumulation of S-adenosylhomocysteine (SAH), with consequent inhibition of transmethylation reactions. 4. In the 24-hr variation of phosphatidylcholine (PC) and phosphatidylethanolamine (PE), the lowest ratio of PC/PE was observed at 24:00-02:00 hr when SAH concentration is high, whereas the highest PC/PE ratio occurs at the same time as one of the SAM/SAH ratio maxima.
Chagoya de Sánchez
V
V
Departamento de Bioenergética, Universidad Nacional Autónoma de México, D.F.
Hernández-Muñoz
R
R
Sánchez
L
L
Vidrio
S
S
Yáñez
L
L
Suárez
J
J
D000241:Adenosine / Q000378:metabolism*; D000818:Animals; D066298:In Vitro Techniques; D007700:Kinetics; D008099:Liver / Q000201:enzymology*; D008297:Male; D008745:Methylation; D010743:Phospholipids / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D012435:S-Adenosylhomocysteine / Q000378:metabolism*; D012436:S-Adenosylmethionine / Q000378:metabolism*
D010743:Phospholipids; D012436:S-Adenosylmethionine; D012435:S-Adenosylhomocysteine; D000241:Adenosine