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Published on: January 16, 2020
[Effects of methionine on the activity of cystathionine-β-synthase]
Lili Shi1, Chao Han1, Shuai Liu2
1National Institute for Nutrition and Health, Chinese Center for Disease Control and Prevention, The Key Laboratory of Trace Element Nutrition of National Health Commission (NHC), Beijing 100050, China.
Objective:
To investigate the effects of methionine on the activity of cystathionine-β-synthase.
Methods:
A total of 56 male rats of the Wistar were randomly divided into 7 groups: 10% casein(10 C) group, 40% casein(40 C) group, 10 C+0.75% L-methionine(10 CM) group, 10 C+amino acid mixture(10 CAA) group, 10 CAA-methionine(10 CAA-Met) group, 10 C+ essential amino acid(10 C+EAA) group, and 10 C+ non-essential amino acid(10 C+NEAA) group, with 8 rats in each group for 10 days.
Results:
The plasma homocysteine concentration significantly increased from(17.1±0.3)μmol/L to(50.7±4.8)μmol/L and(40.5±3.9)μmol/L in rats fed 10 CM and 10 C+EAA diets(P<0.01). Supplementation with methionine induced hyperhomocysteinemia. Compared to 10 C, the activity of hepatic cystathionine-β-synthase(CBS) were significantly increased in the experimental group except for 10 CM(P<0.05). The activity of hepatic CBS was the largest increases in diets with 40 C and the smallest increases in 10 C+NEAA. The activity of hepatic betaine-homocysteine S-methyltransferase(BHMT) were increased in the experimental group except for 10 CAA-Met and 10 C+NEAA(P<0.05).
Conclusion:
The increased CBS activity induced by high protein diets is determined by high amino acid intake rather than methionine supplemention.
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