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N ‐terminal truncation contributed to increasing thermal stability of mannanase Man1312 without activity loss
Author(s) -
Zhou Haiyan,
Yang Wenjiao,
Tian Yun,
Peng Hanhui,
Wu Yongyao
Publication year - 2015
Publication title -
journal of the science of food and agriculture
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.782
H-Index - 142
eISSN - 1097-0010
pISSN - 0022-5142
DOI - 10.1002/jsfa.7240
Subject(s) - thermostability , circular dichroism , mutant , chemistry , enzyme , differential scanning calorimetry , thermal stability , enzyme kinetics , kinetics , residue (chemistry) , biophysics , crystallography , biochemistry , stereochemistry , active site , biology , organic chemistry , physics , quantum mechanics , gene , thermodynamics
BACKGROUND The disordered residues on distal loops affect the molecular structural stability and on some occasions have regulatory roles in catalytic reaction. To increase understanding of the influence of distal residue mutation, this study explored the thermostability and enzymatic activity of mannanase Man1312 deletion mutants. The focus was on residues located on the N ‐terminal region because they are more disordered and changeable. The effects of N ‐terminal truncation on enzymatic activity and thermal dynamics were investigated by spectrophotometry, circular dichroism and differential scanning calorimetry assays. RESULTS The deletion mutants on V3 , N7 and Q11 showed a marked increase in stability, while the enzymatic activity was significantly improved when triplet deletion was carried out. Triplet deletion MandVNQ showed around double the stability of its corresponding single‐site and double‐site deletion mutants. The T m value of MandVNP was about 8 °C higher than that of Man1312. MandVNP had improved characteristics of T opt by 10 °C, t 1/2 by 10 min and catalytic activity by 11% in comparison with Man1312. Analysis of spectra and modeling showed that MandVNQ had increased helix and strand contents. CONCLUSION N ‐terminal truncation had positive effects on the thermostability and activity of mannanase. © 2015 Society of Chemical Industry