Taxoid metabolism: Taxoid 14β-hydroxylase is a cytochrome P450-dependent monooxygenase
作者:Stefan Jennewein、Christopher D. Rithner、Robert M. Williams、Rodney Croteau
DOI:10.1016/s0003-9861(03)00090-0
日期:2003.5
properties of a taxoid triol monoacetate, and the identity of this product was confirmed by spectroscopic means as 5alpha-acetoxy-10beta,14beta-dihydroxy taxadiene. Microsome preparation from the transformed yeast allowed characterization of this new hydroxylase, which was shown to resemble other cytochrome P450 taxoid hydroxylases with pH optimum at 7.5 and a K(m) value for the taxoid substrate of about
在红豆杉(紫杉)细胞培养物中生产抗癌药紫杉醇通常伴随着带有14β-羟基的旁路多氧化紫杉醇代谢物的形成。最近收购了几种新的半合成的紫杉类中间体,使得能够针对14β-羟化酶和其他类紫杉醇加氧酶筛选一个红豆杉细胞色素P450 cDNA克隆家族。候选细胞色素P450克隆在酵母中功能表达,并通过体内供入放射性标记的5α-乙酰氧基-10β-羟基紫杉二烯和5α,13α-二羟基紫杉二烯进行测试。一个克隆将5alpha-乙酰氧基-10beta-ol(但不是5alpha,13alpha-diol)有效且特异地转化为极性更大的产物,具有紫杉醇三醇单乙酸酯的色谱特性,并通过光谱法确认了该产物的身份为5α-乙酰氧基-10β,14β-二羟基紫杉二烯。用转化酵母制备微粒体可以表征这种新的羟化酶,该酶与其他细胞色素P450紫杉醇羟化酶相似,最适pH为7.5,紫杉醇底物的K(m)值约为50 microM。由于紫杉醇在C14