BACKGROUNDA hydrolysis of glyceryltrioleate catalyzed by Candida rugosa lipase (CRL) was carried out to investigate the interaction of acetaldehyde and CRL. Acetaldehyde at low-dose stimulated CRL activity, but decreased it at high-dose, confirming a typical hormetic phenomenon. The interaction of CRL and low-dose acetaldehyde was investigated by spectroscopic and molecular docking methods. RESULTSAcetaldehyde (0.2215 mmol L-1) increased -helix and -sheet contents of CRL, and enhanced CRL affinity for the substrate based on ATR-FTIR, fluorescence and kinetic analyses. In docking studies, it was found that hydrogen bonds were formed separately between acetaldehyde and the five amino acid residues of CRL molecules, namely Trp188 and Ser389 in -helix segments, Ser209 in -turn region, Gly124 and Gly342 in random coil regions. And the formation of another hydrogen bond between Glu341 in the catalytic triad and Gln338 in the active pocket was also attributed to the change of the hydrophobic cleft conformation from the interaction of acetaldehyde and CRL. CONCLUSIONThe formed hydrogen bonds produced a profound distortion of the secondary structure of CRL molecules, which enhanced the affinity of CRL to the substrate leading to the increase of CRL activity. (c) 2014 Society of Chemical Industry