Document Type : Research Paper

Authors

• Jamshid Mehrvand ¹
• Nasim Hayati Roodbari ²
• Leila Hassani ³
• Vahab Jafarian ⁴
• Khosrow Khalifeh ⁵

¹ Student / department of Biology, Faculty of Sciences, Islamic Azad University, science and research Branch, Tehran, Iran

² Academic staff / Department of Biology, Islamic Azad University, Science and Research Branch

³ Academic Staff / Institute for Advanced studies in sciences

⁴ Academic Staff / Department of Biology, Faculty of Sciences, University of Zanjan, Zanjan, Iran

⁵ Academic Staff / Department of Biology- faculty of sciences- University of Zanjan- Zanjan- Iran

Abstract

Cyclomaltodextrinase (CDase) is belonging to a class of enzymes that are involved in carbohydrate degradation. It is one of the most important enzymes from the amylase family with highly important industrial applications. Recently, a variant of native CDase has characterized and reported (Accession number: AMB26774). Previous study on this enzyme and three representative mutants including A123V, C127Q and their respective double mutant, A123V/C127Q has shown that applying point mutations on the interface between the subunits has functional and structural consequences. In current work, complete set of experimental study and modelling procedures was performed to elucidate the thermodynamics behavior of the enzyme variants in chemical denaturation experiments using Guanidinium chloride (GdmCl) as chemical denaturant. It was shown that the wild-type protein with the maximum value of ∆G^(H_2 O) is the most stable variant, as compared with mutants. It appears that the replacement of residues at positions 123 and 127 leads to increasing the flexibility of the protein chains and that the feasibility of the GdmCl penetration and interaction with mutants as compared with the WT protein. We concluded that these positions are hot spot points that can be more manipulated to change the structural features of the enzyme toward thermal and chemical stability.

Keywords

• Amylase
• Thermal stability
• Unfolding
• Biothermodynamics

Main Subjects

• Biophysics