title: Horse heart cytochrome c entrapped into the hydrated liquid-crystalline phases of phytantriol: X-ray diffraction and Raman spectroscopic characterization.
abstract: 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 Q(230) and Q(224) liquid-crystalline phases of hydrated Phyt to such an extent that they transform into the Q(229) phase with the Im3m space group. RR data revealed that entrapment of oxidized Cyt c into the Q(230) 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(-1) (γ(21)) and ν(48) mode at 633 cm(-1), it was demonstrated that the protein matrix tension on the heme group is relaxed upon incorporation of protein into Q(230) phase. Non-resonant Raman bands of difference spectra showed the preservation of α-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.
authors.affiliation: Institute of Biochemistry, Vilnius University, Vilnius, Lithuania.
authors.forename: Audrius
authors.initials: A
authors.lastname: Misiūnas
authors.forename: Gediminas
authors.initials: G
authors.lastname: Niaura
authors.forename: Justas
authors.initials: J
authors.lastname: Barauskas
authors.forename: Rolandas
authors.initials: R
authors.lastname: Meškys
authors.forename: Rasa
authors.initials: R
authors.lastname: Rutkienė
authors.forename: Valdemaras
authors.initials: V
authors.lastname: Razumas
authors.forename: Tommy
authors.initials: T
authors.lastname: Nylander
mesh_terms: D000818:Animals; D045304:Cytochromes c / Q000737:chemistry*; D004800:Enzymes, Immobilized / Q000737:chemistry*; D005233:Fatty Alcohols / Q000737:chemistry*; D006418:Heme / Q000737:chemistry; D006736:Horses; D050866:Liquid Crystals / Q000737:chemistry*; D009124:Muscle Proteins / Q000737:chemistry*; D009206:Myocardium / Q000737:chemistry*; D049329:Nanostructures / Q000737:chemistry*; D013059:Spectrum Analysis, Raman; D014961:X-Ray Diffraction
chemical_list: D004800:Enzymes, Immobilized; D005233:Fatty Alcohols; D009124:Muscle Proteins; D006418:Heme; C508873:3,7,11,15-tetramethyl-1,2,3-hexadecanetriol; D045304:Cytochromes c