Shifting pH optimum of Bacillus circulans xylanase based on molecular modeling.
Although hydrolases are used in several industrial processes, its industrial applications have some limitations in specific cases since some industrial processes are carried out at pH value which is different from optimum pH of the enzyme. Alkaline side optimum pH of hydrolases is always desirable, and it is proved difficult to achieve that by mutation only. Hence, molecular modeling was applied to select the promising mutants. The changes in electrostatic potential, which was calculated using Delphi, were compared to the changes in pH optimum of four hydolases and their mutants. The results showed that the change in electrostatic potential can be used as an indicator for selecting relevant candidates of mutation. Bacillus circulans xylanase was selected as a model system, and the promising mutants were picked up by the molecular modeling. Q167M and R73V, had a higher pH optimum than the wild type, while K175Q had a similar pH-activity profile of the wild type.
Yang
Ji Hye
JH
School of Chemical and Biological Engineering, Seoul National University, Seoul 151-744, Republic of Korea.
Park
Jae Yeon
JY
Kim
Seok Hwan
SH
Yoo
Young Je
YJ
D000595:Amino Acid Sequence; D001407:Bacillus / Q000201:enzymology*; D002384:Catalysis; D006863:Hydrogen-Ion Concentration; D006867:Hydrolases / Q000378:metabolism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D050505:Mutant Proteins / Q000737:chemistry / Q000378:metabolism; D055672:Static Electricity; D043325:Xylan Endo-1,3-beta-Xylosidase / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism*
D050505:Mutant Proteins; D006867:Hydrolases; D043325:Xylan Endo-1,3-beta-Xylosidase