Galliard T, Phillips D R
Biochem J. 1971 Sep;124(2):431-8. doi: 10.1042/bj1240431.
A lipoxygenase (EC 1.13.1.13) was partially purified from potato tubers and was shown to differ from previously characterized soya-bean lipoxygenases in the positional specificity and pH characteristics of the oxygenation reaction. The potato enzyme converted linoleic acid almost exclusively (95%) into 9-d-hydroperoxyoctadeca-trans-10,cis-12-dienoic acid. The 13-hydroperoxy isomer was only a minor product (5%). Linolenic acid was an equally effective substrate, which was also oxygenated specifically at the 9-position. The enzyme had a pH optimum at 5.5-6.0 and was inactive at pH9.0. A half-maximal velocity was obtained at a linoleic acid concentration of 0.1mm. No inhibition was observed with EDTA (1mm) and cyanide (1mm) or with p-chloromercuribenzoate (0.2mm). Haemoproteins were not involved in the lipoxygenase activity. The molecular weight of the enzyme was estimated from gel filtration to be approx. 10(5). Preliminary evidence suggested that the enzyme oxygenated the n-10 position of fatty acids containing a penta(n-3, n-6)diene structure.
从马铃薯块茎中部分纯化出一种脂氧合酶（EC 1.13.1.13），结果表明，该酶在氧化反应的位置特异性和pH特性方面与先前已鉴定的大豆脂氧合酶有所不同。马铃薯酶几乎将亚油酸全部（95%）转化为9-d-氢过氧十八碳-反式-10,顺式-12-二烯酸。13-氢过氧异构体只是次要产物（5%）。亚麻酸是同样有效的底物，它也在9位被特异性氧化。该酶的最适pH为5.5 - 6.0，在pH9.0时无活性。在亚油酸浓度为0.1mm时获得最大反应速度的一半。未观察到EDTA（1mm）、氰化物（1mm）或对氯汞苯甲酸（0.2mm）有抑制作用。血红素蛋白不参与脂氧合酶活性。通过凝胶过滤估计该酶的分子量约为10⁵。初步证据表明，该酶对含有五烯（n-3，n-6）二烯结构的脂肪酸的n-10位进行氧化。
