Oku H, Onotogi M, Nagata J, Wada K, Chinen I
Laboratory of Applied Biochemistry, Faculty of Agriculture, University of The Ryukyus, Okinawa-ken, Japan.
Biosci Biotechnol Biochem. 1995 May;59(5):891-5. doi: 10.1271/bbb.59.891.
Iso- and anteiso-fatty acids are detected in more than trace amounts in rat skin surface lipid. The terminal portion of even carbon number iso- and anteiso-fatty acids are synthesized respectively from valine (Val) and isoleucine (Ile) by essentially the same reaction sequences established for straight chain fatty acids. This paper describes the stereospecific biosynthesis of these branched chain fatty acids (BCFAs) and alcohols (BCFALs) in rat skin. Dependence of the concentration of these BCFAs on dietary L-Val and L-Ile was studied. Concentrations of even carbon number iso- and anteiso-fatty acid increased respectively with dietary L-Val and L-Ile. The saturation dose appeared to be 2% for L-Val and 1% for L-Ile. Supplementation of the diet with 2% D-Val, however, did not affect the concentration of even carbon number iso-fatty acid in rat skin surface lipid despite a comparable serum Val level to that of the 2% L-Val group. A similar experiment using 1% DL-Ile found that L-isomer, but not D-isomer, in the circulation was used for the biosynthesis of anteiso-fatty acids. This view was applicable to the incorporation of D-Val and DL-Ile into related BCFALs.
在大鼠皮肤表面脂质中检测到了异脂肪酸和反异脂肪酸，其含量超过痕量。偶数碳数的异脂肪酸和反异脂肪酸的末端部分分别由缬氨酸（Val）和异亮氨酸（Ile）通过与直链脂肪酸相同的反应序列合成。本文描述了大鼠皮肤中这些支链脂肪酸（BCFAs）和醇（BCFALs）的立体特异性生物合成。研究了这些BCFAs浓度对膳食L-缬氨酸和L-异亮氨酸的依赖性。偶数碳数的异脂肪酸和反异脂肪酸的浓度分别随膳食L-缬氨酸和L-异亮氨酸的增加而增加。L-缬氨酸的饱和剂量似乎为2%，L-异亮氨酸为1%。然而，用2%D-缬氨酸补充饮食，尽管血清缬氨酸水平与2%L-缬氨酸组相当，但并未影响大鼠皮肤表面脂质中偶数碳数异脂肪酸的浓度。使用1%DL-异亮氨酸进行的类似实验发现，循环中的L-异构体而非D-异构体用于反异脂肪酸的生物合成。这一观点适用于D-缬氨酸和DL-异亮氨酸掺入相关BCFALs的情况。
