Yemm R S, Poulton J E
Arch Biochem Biophys. 1986 Jun;247(2):440-5. doi: 10.1016/0003-9861(86)90604-1.
Five multiple forms (forms 1-5) of mandelonitrile lyase (EC 4.1.2.10) which catalyze the decomposition of mandelonitrile to benzaldehyde and hydrogen cyanide have been extensively purified from seeds of black cherry (Prunus serotina Ehrh.) by concanavalin A-Sepharose 4B chromatography and chromatofocusing. These forms are monomers which differ only slightly in molecular weight (57,000-59,000) and isoelectric point (4.58-4.63), but heterogeneity in their carbohydrate side-chains was suggested by concanavalin A-Sepharose 4B chromatography. The absorption spectra of the predominating forms 4 and 5 showed maxima of 278, 380, and 460 nm, indicative of flavoprotein character. Detailed comparative kinetic studies of forms 4 and 5 revealed few significant differences in behavior. Both proteins showed pH optima between 6.0 and 7.0, had identical Km values (0.17 mM) for (R,S)-mandelonitrile, and retained similar activities upon storage at 4 and -20 degrees C. Neither form exhibited a metal ion requirement and both were affected similarly by metal salts, beta-mercaptoethanol, and sulfhydryl reagents. Benzoic acid, p-hydroxybenzyl alcohol, and benzyl alcohol inhibited both forms.
已通过伴刀豆球蛋白A-琼脂糖4B层析和色谱聚焦法，从黑樱桃（Prunus serotina Ehrh.）种子中对催化扁桃腈分解为苯甲醛和氰化氢的五种扁桃腈裂解酶（EC 4.1.2.10）的多种形式（形式1-5）进行了广泛纯化。这些形式均为单体，分子量（57,000 - 59,000）和等电点（4.58 - 4.63）仅有细微差异，但伴刀豆球蛋白A-琼脂糖4B层析表明其碳水化合物侧链存在异质性。主要形式4和5的吸收光谱显示在278、380和460 nm处有最大值，表明具有黄素蛋白特征。对形式4和5进行的详细比较动力学研究显示，二者在行为上几乎没有显著差异。两种蛋白质的最适pH均在6.0至7.0之间，对（R,S）-扁桃腈的Km值相同（0.17 mM），并且在4℃和 - 20℃储存时保留了相似的活性。两种形式均不表现出对金属离子的需求，并且受金属盐、β-巯基乙醇和巯基试剂的影响相似。苯甲酸、对羟基苄醇和苄醇均抑制这两种形式。
