caa a22 4500 605512930 CHVBK 20210128100658.0 cr unu---uuuuu 210128e20150801xx s 000 0 eng 10.1007/s00894-015-2724-z doi (NATIONALLICENCE)springer-10.1007/s00894-015-2724-z Functional role of R462 in the degradation of hyaluronan catalyzed by hyaluronate lyase from Streptococcus pneumoniae [Elektronische Daten] [Fengxue Li, Dingguo Xu] Hyaluronan lyase from Streptococcus pneumoniae can degrade hyaluronic acid, which is one of the major components in the extracellular matrix. Hyaluronan can regulate water balance, osmotic pressure, and act as an ion exchange resin. Followed by our recent work on the catalytic reaction mechanism and substrate binding mode, we in this work further investigate the functional role of active site arginine residue, R462, in the degradation of hyaluronan. The site directed mutagenesis simulation of R462A and R462Q were modeled using a combined quantum mechanical and molecular mechanical method. The overall substrate binding features upon mutations do not have significant changes. The energetic profiles for the reaction processes are essentially the same as that in wild type enzyme, but significant activation barrier height changes can be observed. Both mutants were shown to accelerate the overall enzymatic activity, e.g., R462A can reduce the barrier height by about 2.8kcal mol-1, while R462Q reduces the activation energy by about 2.9kcal mol-1. Consistent with the active site model calculated using density functional theory, our results can support that the positive charge on R462 guanidino side chain group plays a negative role in the catalysis. Finally, the functional role of R462 was proposed to facilitate the formation of initial enzyme-substrate complex, but not in the subsequent catalytic degradation reaction. Graphical Abstract Degradation of hyaluronan catalyzed by hyaluronate lyase from Streptococcus pneumoniae Springer-Verlag Berlin Heidelberg, 2015 Enzymatic catalysis nationallicence Hyaluronan lyase nationallicence Molecular dynamics nationallicence QM/MM nationallicence Reaction mechanism nationallicence Site-directed mutagenesis nationallicence Li Fengxue MOE Key Laboratory of Green Chemistry, College of Chemistry, Sichuan University, 610064, Chengdu, Sichuan, People's Republic of China aut Xu Dingguo MOE Key Laboratory of Green Chemistry, College of Chemistry, Sichuan University, 610064, Chengdu, Sichuan, People's Republic of China aut Journal of Molecular Modeling Springer Berlin Heidelberg 21/8(2015-08-01), 1-13 1610-2940 21:8<1 2015 21 894 https://doi.org/10.1007/s00894-015-2724-z text/html Onlinezugriff via DOI BK010053 XK010053 XK010000 Metadata rights reserved Springer special CC-BY-NC licence nationallicence 1 research-article jats NATIONALLICENCE NATIONALLICENCE NL-springer NATIONALLICENCE 856 40 https://doi.org/10.1007/s00894-015-2724-z text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Li Fengxue MOE Key Laboratory of Green Chemistry, College of Chemistry, Sichuan University, 610064, Chengdu, Sichuan, People's Republic of China aut NATIONALLICENCE 700 1- Xu Dingguo MOE Key Laboratory of Green Chemistry, College of Chemistry, Sichuan University, 610064, Chengdu, Sichuan, People's Republic of China aut NATIONALLICENCE 773 0- Journal of Molecular Modeling Springer Berlin Heidelberg 21/8(2015-08-01), 1-13 1610-2940 21:8<1 2015 21 894