Smulevich G, Feis A, Focardi C, Tams J, Welinder K G
Dipartimento di Chimica, Universitá di Firenze, Italy.
Biochemistry. 1994 Dec 27;33(51):15425-32. doi: 10.1021/bi00255a024.
Resonance Raman (RR) spectra for the resting state ferric and the reduced ferrous forms of recombinant Coprinus cinereus peroxidase (CIP), obtained with different excitation wavelengths and in polarized light, are reported. The spectra are compared with those obtained previously for cytochrome c peroxidase expressed in Escherichia coli [(CCP(MI)] and horseradish peroxidase (HRP-C). Although the enzymic properties of CIP and HRP-C are similar, the RR data show that, in terms of the heme cavity structures, CIP and CCP(MI) are much more closely related to each other than to HRP-C. The ferric state of CIP at neutral pH is characteristic mainly of a five-coordinate high spin heme. However, the lower frequency of the v2 mode and a higher frequency of the v(C = C) vinyl stretching modes for CIP as compared to CCP, indicate a higher degree of vibrational coupling between the two modes in CIP. In addition, CIP is rather unstable under low laser power irradiation as an irreversible transition to a six-coordinate high spin heme followed by a second transition to a six-coordinate low spin heme is observed. This instability of CIP as compared to CCP(MI) is proposed to be a consequence of the presence of a distal Phe54 in CIP rather than the homologous Trp51 in CCP, as Trp51 is hydrogen-bonded to a distal water molecule located above the heme Fe thereby preventing its coordination in CCP. In CIP the FeII-His RR band has two components with frequencies at 230 and 211 cm-1.(ABSTRACT TRUNCATED AT 250 WORDS)
报道了在不同激发波长和偏振光条件下获得的重组灰盖鬼伞过氧化物酶（CIP）的静止态铁离子形式和还原亚铁形式的共振拉曼（RR）光谱。将这些光谱与先前在大肠杆菌中表达的细胞色素c过氧化物酶[CCP(MI)]和辣根过氧化物酶（HRP-C）所获得的光谱进行了比较。尽管CIP和HRP-C的酶学性质相似，但RR数据表明，就血红素腔结构而言，CIP和CCP(MI)彼此之间的关系比它们与HRP-C的关系更为密切。中性pH条件下CIP铁离子态主要特征为五配位高自旋血红素。然而，与CCP相比，CIP的v2模式频率较低，v(C = C)乙烯基伸缩模式频率较高，这表明CIP中这两种模式之间的振动耦合程度更高。此外，在低激光功率照射下CIP相当不稳定，观察到其不可逆地转变为六配位高自旋血红素，随后又转变为六配位低自旋血红素。与CCP(MI)相比，CIP的这种不稳定性被认为是由于CIP中存在远端苯丙氨酸54，而不是CCP中的同源色氨酸51，因为色氨酸51与位于血红素铁上方的远端水分子形成氢键，从而阻止了其在CCP中的配位。在CIP中，FeII-His RR带具有两个频率分别为230和211 cm-1的组分。（摘要截短于250字）
