title: Molecular mechanism of carbon nanotube to activate Subtilisin Carlsberg in polar and non-polar organic media.
abstract: In the work, we mainly used molecular dynamics (MD) simulation and protein structure network (PSN) to study subtilisin Carlsberg (SC) immobilized onto carbon nanotube (CNT) in water, acetonitrile and heptane solvents, in order to explore activation mechanism of enzymes in non-aqueous media. The result indicates that the affinity of SC with CNT follows the decreasing order of water > acetonitrile > heptane. The overall structure of SC and the catalytic triad display strong robustness to the change of environments, responsible for the activity retaining. However, the distances between two β-strands of substrate-binding pocket are significantly expanded by the immobilization in the increasing order of water < acetonitrile < heptane, contributing to the highest substrate-binding energy in heptane media. PSN analysis further reveals that the immobilization enhances structural communication paths to the substrate-binding pocket, leading to its larger change than the free-enzymes. Interestingly, the increase in the number of the pathways upon immobilization is not dependent on the absorbed extent but the desorbed one, indicating significant role of shifting process of experimental operations in influencing the functional region. In addition, some conserved and important hot-residues in the paths are identified, providing molecular information for functional modification.
authors.affiliation: Faculty of Chemistry, Sichuan University, Chengdu 610064, People's Republic of China.
authors.forename: Liyun
authors.initials: L
authors.lastname: Zhang
authors.affiliation: Faculty of Chemistry, Sichuan University, Chengdu 610064, People's Republic of China.
authors.forename: Yuzhi
authors.initials: Y
authors.lastname: Li
authors.affiliation: College of Management, Southwest University for Nationalities, Chengdu 610041, People's Republic of China.
authors.forename: Yuan
authors.initials: Y
authors.lastname: Yuan
authors.affiliation: Faculty of Chemistry, Sichuan University, Chengdu 610064, People's Republic of China.
authors.forename: Yuanyuan
authors.initials: Y
authors.lastname: Jiang
authors.affiliation: Faculty of Chemistry, Sichuan University, Chengdu 610064, People's Republic of China.
authors.forename: Yanzhi
authors.initials: Y
authors.lastname: Guo
authors.affiliation: Faculty of Chemistry, Sichuan University, Chengdu 610064, People's Republic of China.
authors.forename: Menglong
authors.initials: M
authors.lastname: Li
authors.affiliation: Faculty of Chemistry, Sichuan University, Chengdu 610064, People's Republic of China.
authors.forename: Xuemei
authors.initials: X
authors.lastname: Pu