McKeon T A, Stumpf P K
J Biol Chem. 1982 Oct 25;257(20):12141-7.
Two enzymes involved in oleic acid biosynthesis have been purified from immature safflower seed. The stearoyl-acyl carrier protein (ACP) desaturase which catalyzes the formation of the double bond of oleate has been purified 200-fold and is a dimer with a molecular weight of 68,000. The enzyme shows strong preference for stearoyl-ACP as substrate; by comparison of its activity with stearoyl-CoA and palmitoyl-ACP as substrates, it appears that the ACP moiety is primarily important for binding of substrate and the chain length is important for catalytic activity. The desaturase requires 56 microM oxygen for half-maximal activity, 400 microM oxygen for maximal activity, and is stimulated severalfold by catalase. The acyl-ACP thioesterase has been purified 700-fold and is also a dimer of molecular weight 74,000. It shows a 5-fold preference for oleoyl-ACP versus stearoyl-ACP and is relatively inactive with corresponding acyl-CoAs.
已从未成熟的红花种子中纯化出两种参与油酸生物合成的酶。催化油酸双键形成的硬脂酰 - 酰基载体蛋白（ACP）去饱和酶已被纯化200倍，是一种分子量为68,000的二聚体。该酶对硬脂酰 - ACP作为底物表现出强烈偏好；通过比较其以硬脂酰 - CoA和棕榈酰 - ACP作为底物时的活性，似乎ACP部分对底物结合至关重要，而链长对催化活性很重要。该去饱和酶半最大活性需要56微摩尔氧气，最大活性需要400微摩尔氧气，并且受到过氧化氢酶的几倍刺激。酰基 - ACP硫酯酶已被纯化700倍，也是一种分子量为74,000的二聚体。与硬脂酰 - ACP相比，它对油酰 - ACP的偏好高5倍，并且对相应的酰基 - CoA相对无活性。
