아미드 결합 분해 활성을 갖는 리파제 변형체 생성에 대한 연구

Abstract

Because lipases have high reactivity, selectivity, and stability in organic solvent, they are used in industrial and academic areas. In addition, lipases are relatively inexpensive and commercially available. Lipases have the catalytic triad, Asp-His-Ser, which is similar to that of serine proteases. However, most lipases cannot hydrolyze amide bonds although serine-proteases catalyze hydrolysis of amide bonds. This phenomenon is not yet fully understood and comprehending its molecular basis remains a challenge for researchers. For this reason, lipases have a limit to produce chiral amines, which is an important building block in pharmaceutical industry. Therefore, research to create lipase variants containing high activity toward chiral amines is important in academia and industry. This thesis deals with rational design for improving amidase activity of Candida antarctica lipase B, and understanding different activities lipase and serine-protease. Based on the assumption of the previous study, a residue, such as Met, Asp, Glu, Gln, was introduced near the active site to provide a hydrogen bond with the amide nitrogen atom. Total ten mutant enzymes were created. Among them, the I189Q mutant enzyme showed eleven-fold faster hydrolysis activity toward p-nitroacetanilide than the wild-type enzyme.