科研之友
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摘要
The cytochromes P450 (CYPs) are heme proteins responsible for the oxidation of xenobiotics and pharmaceuticals and the biosynthesis of essential steroid products. In all cases, substrate binding initiates the enzymatic cycle, converting ferric low-spin to high-spin state, with the efficiency of the conversion varying widely for different substrates, so documentation of this conversion for a given substrate is an important objective. Resonance Raman (rR) spectroscopy can effectively yield distinctive frequencies for the (3) spin state marker%26apos; bands. Here, employing a reference cytochrome P450 (CYP101), the intensities of the (3) modes (I-LS) and (I-HS) relative to an internal standard (sodium sulfate) yield relative populations for the two spin states; i.e., a value of 1.24 was determined for the ratio of the relative cross sections for the (3) modes. The use of this value was then shown to permit a reliable calculation of relative populations of the two spin states from rR spectra of several other CYPs P450. The importance of this work is that, using this information, it is now possible to conveniently document by rR the spin state population without conducting separate experiments requiring different analytical methods, instrumentation, and additional sample.
- 出版日期2013-12
