代谢
在体内,饮食中的甲硫氨酸转化为同型半胱氨酸。通过一系列的代谢步骤,胱硫醚β-合成酶(CBS)不可逆地生成一种名为胱硫醚的物质。同型半胱氨酸从甲硫氨酸生成然后转化为胱硫醚的速度显然是由习惯性饮食中甲硫氨酸的摄入量决定的。L-同型半胱氨酸有两个主要去向:通过四氢叶酸(THF)转化回L-甲硫氨酸,或者转化为L-胱氨酸。同型半胱氨酸可以环化生成同型半胱氨酸硫内酯,一个五元杂环,这个反应由甲硫氨酰-tRNA合成酶催化。
In the body, dietary methionine is converted to homocysteine. In a series of metabolic steps, the enzyme cystathionine b-synthase (CBS) irreversibly generates a substance called cystathionine from homocysteine. The rate at which homocysteine is generated from methionine and then converted to cystathionine is evidently determined by the habitual dietary intake of methionine. L-Homocysteine has two primary fates: conversion via tetrahydrofolate (THF) back into L-methionine or conversion to L-cysteine. Homocysteine can cyclize to give homocysteine thiolactone, a five-membered heterocycle, a reaction catalyzed by methionyl-transfer RNA synthetase.
来源:Toxin and Toxin Target Database (T3DB)