Nam SH, Ko EA, Jang SS, Kim DW, Kim SY, Hwang DS, Kim D. Maximization of dextransucrase activity expressed in E. coli by mutation and its functional characterization.
Biotechnol Lett 2007;
30:135-43. [PMID:
17673948 DOI:
10.1007/s10529-007-9498-z]
[Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2007] [Revised: 07/17/2007] [Accepted: 07/17/2007] [Indexed: 10/23/2022]
Abstract
A novel dextransucrase gene, DSRN, was obtained by ultrasoft X-ray treatment of the DSRB742 gene. The DSRN gene was further mutated via site-directed mutagenesis producing four mutants: DSRN1 (F196S), DSRN2 (Y346N), DSRN3 (K395T) and DSRN4 (P980T). Dextransucrases derived from DSRB742 and its mutants were expressed in E. coli and affinity-purified using dextran to give 80% purity. They had specific activities of 0.6-17 U/mg with Km values of 18-88 mM. DSRB742 had the lowest (0.02 s(-1) x mM(-1)) and DSRN1 had the highest (0.13 s(-1) x mM(-1)) Kcat/Km values. DSRN3 had the highest enzymatic transglycosylation efficiency with maltose (63% of theoretical), gentiobiose (39%), or salicine (40%).
Collapse