Chinese Journal of Applied Chemistry ›› 2016, Vol. 33 ›› Issue (4): 436-441.DOI: 10.11944/j.issn.1000-0518.2016.04.150268

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Effect of Site-Directed Mutagenesis in Coenzyme-Binding Domain of Malic Enzyme on Coenzyme Activities for Nicotinamide Adenine Dinucleotide Analogs

HOU Shuhuaa*(),JI Debinb,LIU Wujunb,WANG Leib   

  1. aDepartment of Chemistry,Bohai University,Jinzhou,Liaoning 121013,China
    bDalian Institute of Chemical Physics,Chinese Academy of Sciences,Dalian,Liaoning 116023,China
  • Received:2015-07-28 Accepted:2015-12-08 Published:2016-04-01 Online:2016-04-01
  • Contact: HOU Shuhua

Abstract:

The cofactor-binding domains of malic enzyme(ME) L310, Q401 and L404 were found to have a steric effect on binding of nicotinamide adenine dinucleotide(NAD+). The site-directed mutagenesis of these three sites shows that the cofactor activities of NAD+ analogs(B1~B7) change in some level, indicating that these sites have a critical role in binding the cofactors. A high-throughput screen between malic enzyme mutants and NAD+ analogs affords 2 different mutants capable of taking NAD+ analogs as the cofactor. ME-Q401H/L404T has a 50-fold higher kcat/Km than the that of wild-type ME for the analog B4. For ME-L310M/Q401N, the kcat/Km are 16-fold and 5-fold higher than those of wild-type ME for the cofactors B4 and B3. The coenzyme activity can be increased through site-directed mutagenesis of cofactor-binding domains.

Key words: malic enzyme, site-directed mutagenesis, coenzyme activity