Imai Y, Nakamura M
Institute for Protein Research, Osaka University, Japan.
FEBS Lett. 1988 Jul 18;234(2):313-5. doi: 10.1016/0014-5793(88)80106-6.
Threonine-301 from rabbit liver cytochromes P-450 (laurate (omega-1)-hydroxylase and testosterone 16 alpha-hydroxylase) has been replaced by histidine via site-directed mutagenesis. In the oxidized state the mutant P-450s exhibited typical low-spin type absorption spectra of P-450 and their reduced CO complexes showed a Soret peak at 450 nm. However, no spectral change was induced on addition of substrates for their wild-type counterparts. The mutant P-450s were also completely devoid of the hydroxylase activity. These findings suggest that threonine-301, which is highly conserved in P-450s and located at the distal heme surface, plays an important role in substrate binding.
通过定点诱变，兔肝细胞色素P - 450（月桂酸（ω-1）羟化酶和睾酮16α-羟化酶）的苏氨酸-301已被组氨酸取代。在氧化状态下，突变型P - 450呈现出典型的P - 450低自旋型吸收光谱，其还原态的一氧化碳复合物在450 nm处有一个Soret峰。然而，加入其野生型对应物的底物后未诱导出光谱变化。突变型P - 450也完全没有羟化酶活性。这些发现表明，在P - 450中高度保守且位于血红素远端表面的苏氨酸-301在底物结合中起重要作用。
