Rebouche C J, Engel A G
Biochim Biophys Acta. 1980 Jun 5;630(1):22-9. doi: 10.1016/0304-4165(80)90133-6.
The distribution in human tissues of enzymes which convert epsilon-N-trimethyl-L-lysine to L-carnitine was studied. Existing methodology was modified and new procedures were developed to measure enzyme activities. Epsilon-N-Trimethyl-L-lysine was converted to gamma-butyrobetaine in three enzymatic steps (hydroxylation at carbon 3, aldol cleavage between carbons 2 and 3 to yield glycine and gamma-trimethylaminobutyraldehyde, and subsequent oxidation of the aldehyde) in all tissues studied (liver, brain, kidney, heart and skeletal muscle), but gamma-butyrobetaine was hydroxylated to form L-carnitine only in liver, kidney and brain. Gamma-Butyrobetaine hydroxylase (4-trimethylaminobutyrate, 2-oxoglutarate: oxygen oxidoreductase (3-hydroxylating), EC 1.14.11.1) activity in liver was dependent on the age of the subject. The activity rose from 12% in infants to 100% of the adult mean by age 15 years. No age dependence could be demonstrated for the other three enzymes studied.
研究了将ε-N-三甲基-L-赖氨酸转化为L-肉碱的酶在人体组织中的分布情况。对现有方法进行了改进，并开发了新的程序来测量酶活性。在所有研究的组织（肝脏、大脑、肾脏、心脏和骨骼肌）中，ε-N-三甲基-L-赖氨酸通过三个酶促步骤（在碳3处羟基化、在碳2和碳3之间进行醛醇裂解生成甘氨酸和γ-三甲基氨基丁醛，以及随后醛的氧化）转化为γ-丁酰甜菜碱，但γ-丁酰甜菜碱仅在肝脏、肾脏和大脑中被羟基化形成L-肉碱。肝脏中的γ-丁酰甜菜碱羟化酶（4-三甲基氨基丁酸，2-氧代戊二酸：氧氧化还原酶（3-羟基化），EC 1.14.11.1）活性取决于受试者的年龄。该活性从婴儿期的12%上升到15岁时达到成人平均水平的100%。对于所研究的其他三种酶，未显示出年龄依赖性。
