出版社：American Society for Biochemistry and Molecular Biology
摘要：Biliary bile salt composition of 677 vertebrate species (103 fish, 130 reptiles, 271 birds, 173 mammals) was determined. Bile salts were of three types: C27 bile alcohols, C27 bile acids, or C24 bile acids, with default hydroxylation at C-3 and C-7. C27 bile alcohols dominated in early evolving fish and amphibians; C27 bile acids, in reptiles and early evolving birds. C24 bile acids were present in all vertebrate classes, often with C27 alcohols or with C27 acids, indicating two evolutionary pathways from C27 bile alcohols to C24 bile acids: a ) a ‘direct’ pathway and b ) an ‘indirect’ pathway with C27 bile acids as intermediates. Hydroxylation at C-12 occurred in all orders and at C-16 in snakes and birds. Minor hydroxylation sites were C-1, C-2, C-5, C-6, and C-15. Side chain hydroxylation in C27 bile salts occurred at C-22, C-24, C-25, and C-26, and in C24 bile acids, at C-23 (snakes, birds, and pinnipeds). Unexpected was the presence of C27 bile alcohols in four early evolving mammals. Bile salt composition showed significant variation between orders but not between families, genera, or species. Bile salt composition is a biochemical trait providing clues to evolutionary relationships, complementing anatomical and genetic analyses.
