Horse heart cytochrome c entrapped into the hydrated liquid-crystalline phases of phytantriol: X-ray diffraction and Raman spectroscopic characterization

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• 作者：Audrius Misi奴nas^a ; Gediminas Niaura^a ; ^{gniaura@ktl.mii.lt} ; Justas Barauskas^a ; Rolandas Me&scaron ; kys^a ; Rasa Rutkien臈^a ; Valdemaras Razumas^a ; Tommy Nylander^b
• 关键词：Phytantriol ; Cytochrome c ; SAXD ; Resonance Raman spectroscopy ; Liquid-crystalline phases
• 刊名：Journal of Colloid and Interface Science
• 出版年：2012
• 期刊代码：125_00219797
• 类别：ch
• 出版时间：15 July, 2012
• 卷：378
• 期：1
• 页码：232-240
• 文件大小：969 K

摘要

Small angle X-ray diffraction (SAXD), resonance Raman (RR) spectroscopy with 413 nm excitation, and non-resonance Raman technique with 785 nm excitation were used to probe the influence of entrapped cytochrome c (Cyt c) on the structure of hydrated phytantriol (Phyt) liquid-crystalline phases as well as conformational changes of heme group and secondary structure of the protein. SAXD measurements indicated that incorporation of Cyt c affects both nanostructure dimensions and type of liquid-crystalline phases of hydrated Phyt. The unit cell dimensions decrease with increasing Cyt c concentration for all phases. In addition, protein perturbs the nanostructure of Q²³⁰ and Q²²⁴ liquid-crystalline phases of hydrated Phyt to such an extent that they transform into the Q²²⁹ phase with the Im3m space group. RR data revealed that entrapment of oxidized Cyt c into the Q²³⁰ phase at 1 wt.%content results in near complete reduction of central iron ion of the heme group, while its low-spin state and six-ligand coordination configuration are preserved. Based on the analysis of heme out-of-plane folding vibration near 568 cm^鈭? (纬₂₁) and 谓₄₈ mode at 633 cm^鈭?, it was demonstrated that the protein matrix tension on the heme group is relaxed upon incorporation of protein into Q²³⁰ phase. Non-resonant Raman bands of difference spectra showed the preservation of 伪-helix secondary structure of Cyt c in the liquid-crystalline phase at relatively high (5 wt.%) content. The Cyt c induced spectroscopic changes of Phyt bands were found to be similar as decrease in temperature.