A chemically modified alpha-amylase with a molten-globule state has entropically driven enhanced thermal stability

Siddiqui, Khawar Sohail, Poljak, Anne, De Francisci, Davide, Guerriero, Gea, Pilak, Oliver, Burg, Dominic, Raftery, Mark J, Parkin, Don M, Trewhella, Jill and Cavicchioli, Ricardo (2010) A chemically modified alpha-amylase with a molten-globule state has entropically driven enhanced thermal stability. PEDS: Protein Engineering, Design & Selection, 23, (10), 769-780. (doi:10.1093/protein/gzq051). (PMID:20696745).


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The thermostability properties of TAA were investigated by chemically modifying carboxyl groups on the surface of the enzyme with AMEs. The TAA(MOD) exhibited a 200% improvement in starch-hydrolyzing productivity at 60 degrees C. By studying the kinetic, thermodynamic and biophysical properties, we found that TAA(MOD) had formed a thermostable, MG state, in which the unfolding of the tertiary structure preceded that of the secondary structure by at least 20 degrees C. The X-ray crystal structure of TAA(MOD) revealed no new permanent interactions (electrostatic or other) resulting from the modification. By deriving thermodynamic activation parameters of TAA(MOD), we rationalised that thermostabilisation have been caused by a decrease in the entropy of the transition state, rather than being enthalpically driven. Far-UV CD shows that the origin of decreased entropy may have arisen from a higher helical content of TAA(MOD). This study provides new insight into the intriguing properties of an MG state resulting from the chemical modification of TAA

Item Type: Article
Digital Object Identifier (DOI): doi:10.1093/protein/gzq051
ISSNs: 1741-0126 (print)
1741-0134 (electronic)
Subjects: Q Science > QD Chemistry
Divisions : Faculty of Medicine > Biomedical Research Facility
Faculty of Natural and Environmental Sciences > Biological Sciences > Molecular & Cellular
ePrint ID: 338908
Accepted Date and Publication Date:
9 August 2010Made publicly available
October 2010Published
Date Deposited: 18 May 2012 13:29
Last Modified: 31 Mar 2016 14:28
URI: http://eprints.soton.ac.uk/id/eprint/338908

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