The enzyme ^9 desaturase catalyzes the conversion of stearic acid into?: (A) Linolenic acid, (B) Linoleic acid, (C) Oleic acid, (D) All of the above
Answer is C. The enzyme ^9 desaturase, in endoplasmic reticulum, catalyzes conversion of stearic acid to oleic acid, which is a MUFA. ^9 desaturase is a mixed-function oxidase, requiring NADPH and O2. Humans cannot introduce double bonds beyond ^9 position (between C10 and terminal methyl group). Hence, linoleic (D9,12 ) and linolenic acid (D 9,12,15) are considered essential fatty acids. Reference: Harper's Illustrated Biochemistry 30th Edition Pg 239