LABILE METHYL BALANCES FOR NORMAL HUMANS ON VARIOUS DIETARY REGIMENS
LABILE METHYL BALANCES FOR NORMAL HUMANS ON VARIOUS DIETARY REGIMENS
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DOI：
10.1016/0026-0495(75)90040-2
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发表时间：
1975-01-01
影响因子：
9.8
通讯作者：
POOLE, JR
中科院分区：
文献类型：
--
作者：
MUDD, SH;POOLE, JR
正常的年轻成年男性和女性受试者维持固定的饮食方案，这些饮食方案基本上是正常的或半合成的，减少蛋氨酸和胆碱的摄入量，几乎不含胱氨酸。受试者保持稳定的体重，并保持在正氮平衡或在氮平衡区，并接近硫平衡区。计算胆碱摄入量，测量肌酐、肌酸和肌酐的尿排泄量。基本正常饮食的男性受试者的肌酐排泄量超过了不稳定甲基的总摄入量。考虑到额外的甲基化化合物的分泌，从发表的值判断，它似乎甲基新生通常必须发挥作用，在男性和女性。当不稳定的甲基摄入量被削减，从头形成的甲基基团是定量更显着的比预先形成的甲基部分的摄入。在这些实验中使用的正常饮食中，雄性中的平均同型半胱氨酸部分在转化为胱硫醚之前在甲硫氨酸和同型半胱氨酸之间循环至少1.9次。对于女性，平均周期数至少为1.5。当不稳定的甲基摄入量被削减，平均周期数上升到3.9男性和3.0女性的条件下使用。
Normal young adult male and female subjects were maintained on fixed dietary regimens which were either essentially normal or were semisynthetic and curtailed in methionine and choline intakes and virtually free of cystine. The subjects maintained stable weights and remained in positive nitrogen balance or within the zone of nitrogen equilibrium, and close to the zone of sulfur equilibrium. Choline intakes were calculated, and urinary excretions of creatinine, creatine, and sacrosine were measured. Creatinine excretions of male subjects on essentially normal diets outweighed the total intakes of labile methyl groups. Taking into account the excretions of additional methylated compounds, as judged from published values, it appears that methyl neogenesis must normally play a role in both males and females. When labile methyl intake is curtailed, de novo formation of methyl groups is quantitatively more significant than ingestion of preformed methyl moieties. On the normal diets used in these experiments, the average homocysteinyl moiety in males cycled between methionine and homocysteine at least 1.9 times before being converted to cystathionine. For females, the average number of cycles was at least 1.5. When labile methyl intake was curtailed, the average number of cycles rose to 3.9 for males and 3.0 for females under the conditions employed.