(1)脱氢 脂酰CoA脱氢酶 R-CH2 -CH,C-SCoA FAD-R-CH=CH-C-SCoA+FADH, 脂酰C0A △2-反-烯脂酰CoA （1）脱氢  2 -反-烯脂酰CoA 脂酰CoA脱氢酶 ＋ FAD 脂酰CoA Ｏ R-CH2 - CH2C-SCoA || Ｏ R-CH=CH-C-SCoA || ＋ FADH2