N-terminal Truncation had contribution on increasing thermal stability of mannanase Man1312 without the activity loss.

Journal of the science of food and agriculture

PubMedID: 25930671

Zhou H, Yang W, Tian Y, Peng H, Wu Y. N-terminal Truncation had contribution on increasing thermal stability of mannanase Man1312 without the activity loss. J Sci Food Agric. 2015;.
BACKGROUND
The disordered residues on distal loops affect the molecular structural stability and in some occasions they have regulatory roles in catalytic reaction. To expand our understanding on the influences of distal residues mutation, we explored the thermo-stability and enzymatic activity of mannanase Man1312 deletion mutants. The focused residues are located on the N-terminal region because they are more disordered and changeable. The effects of the N-terminal truncation on enzyme activity and thermal dynamics were investigated by spectrophotometer, circular dichroism and differential scanning calorimetry assays.

RESULTS
The deletion mutants on V3, N7 and Q11 showed marked increase on stability and meanwhile the enzymatic activity was significantly improved when triplet deletion carried out. Triplet deletion MandVNQ showed around double stability than its corresponding single-site deletion and double-site deletion mutants. Tm value of MandVNP was ~8?°C higher than Man1312. MandVNP had promoted characteristics of Topt by 10?°C, t1/2 by 10?min and catalytic activity by 11% in compare with Man1312. Analysis of spectra and modeling, MandVNQ increased its contents of the helix and strand.

CONCLUSION
N-terminal truncation had positive effects on mannanase thermostability and on its activity.