title: Forced unfolding of apocytochrome b5 by steered molecular dynamics simulation.
abstract: Apocytochrome b5 (apocyt b5), a small b-type cytochrome with heme prosthetic group removal, has been subjected to steered molecular dynamics (SMD) simulations for investigating the consequences of mechanical force-induced unfolding. Both constant velocity (0.5 and 1.0 A/ps) and constant force (500, 750 and 1000 pN) stretching have been employed to model forced unfolding of apocyt b5. The results of SMD simulations elucidate that apocyt b5 is protected against external stress mainly through the interstrand hydrogen bonding between its beta1-beta2 and beta2-beta3 strands, highlighting the importance of hydrophobic core 2 in stabilization of apocyt b5. The existence of intermediate states manifested by current simulations in the forced unfolding pathway of apocyt b5 is different from the observations in pervious thermal or chemical unfolding studies in the absence of force. The present study could thus provide insights into the relationship between the two cooperative functional modules of apocyt b5 and also guide the rational molecular design of heme proteins.
authors: College of Chemistry and Chemical Engineering, University of South China, Hunan, Hengyang 421001, PR China. linlinying@hotmail.com
authors: Ying-Wu
authors: YW
authors: Lin
authors: Zhong-Hua
authors: ZH
authors: Wang
authors: Feng-Yun
authors: FY
authors: Ni
authors: Zhong-Xian
authors: ZX
authors: Huang
mesh_terms: D000595:Amino Acid Sequence; D015786:Cytochromes b5 / Q000737:chemistry* / Q000378:metabolism; D009682:Magnetic Resonance Spectroscopy; D018625:Microscopy, Atomic Force; D008958:Models, Molecular; D011487:Protein Conformation; D017510:Protein Folding; D021381:Protein Transport
chemical_list: D015786:Cytochromes b5