[Formation of taurine and amino acid pools in rat tissues upon stimulation of NAD synthesis].
A single intraperitoneal injection of nicotinamide (500 mg/kg) to mongrel albino rats causes a 6-hour increase in the 2-oxoglutarate level and the free NAD+/NADH ratio in liver mitochondria. The levels of taurine and taurocholates as well the activity of cysteine oxidase in liver tissues remains thereby unchanged, whereas the cysteine transaminase activity diminishes. In the heart and brain of experimental animals the activity of both enzymes is decreased. In the liver, blood plasma and heart of experimental animals, the Ala and Ser levels are low, whereas the taurine content is elevated both in blood plasma and brain. Nicotinamide administration eliminates positive correlations between the levels of taurine, its precursors and metabolically bound amino acids. In the liver the negative correlations between the activities of cysteine oxidase and cysteine transaminase observed in the control group disappear in the experimental group. Apparently, one of regulatory mechanisms of the taurine pool formation in the liver is the ratio of activities of the both enzymes as well as their competition at the substrate level. This emphasizes the importance of the transamination reactions in the metabolism of sulphur-containing amino acids.
Nefedov
L I
LI
Bukhmet
M I
MI
Ostrovskiĭ
Iu M
IuM
Moroz
A R
AR
D000596:Amino Acids / Q000096:biosynthesis* / Q000097:blood; D000818:Animals; D001921:Brain / Q000201:enzymology / Q000378:metabolism; D050558:Cysteine Dioxygenase; D049308:Dioxygenases; D004790:Enzyme Induction; D008297:Male; D008930:Mitochondria, Liver / Q000201:enzymology / Q000378:metabolism; D009206:Myocardium / Q000201:enzymology / Q000378:metabolism; D009243:NAD / Q000096:biosynthesis*; D009536:Niacinamide / Q000494:pharmacology; D010105:Oxygenases / Q000378:metabolism; D051381:Rats; D013654:Taurine / Q000097:blood*
D000596:Amino Acids; D009243:NAD; D013654:Taurine; D009536:Niacinamide; D010105:Oxygenases; D049308:Dioxygenases; D050558:Cysteine Dioxygenase
Formirovanie taurinovogo pula i aminokislotnogo fonda v tkaniakh krys v usloviiakh stimuliatsii sinteza NAD.