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

A chemically modified alpha-amylase with a molten-globule state has entropically driven enhanced thermal stability
A chemically modified alpha-amylase with a molten-globule state has entropically driven enhanced thermal stability
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
1741-0126
769-780
Siddiqui, Khawar Sohail
02cff74f-dcd2-4336-bdfb-0c8bcc56c630
Poljak, Anne
114fe1b4-3275-4d81-8d9c-ff523cd18254
De Francisci, Davide
9d232dd9-241d-4d06-98f7-053227a42012
Guerriero, Gea
4659a0c1-71fd-446b-8d19-3373db103c58
Pilak, Oliver
b7025bf7-7e05-4194-8aae-67b26f977a6f
Burg, Dominic
a51bc2a5-54d3-40ee-ac66-4ca0bc4d9d1d
Raftery, Mark J
a63e7f96-ecfa-4ec7-8f25-367b82e6b7b3
Parkin, Don M
59d5938a-2f68-4008-a8fb-e53981e4f621
Trewhella, Jill
5e106475-ba69-40ea-b1d1-0bbad5a9b01c
Cavicchioli, Ricardo
95c04c14-6cdd-4f0d-afc6-32bdbfa53ad9
Siddiqui, Khawar Sohail
02cff74f-dcd2-4336-bdfb-0c8bcc56c630
Poljak, Anne
114fe1b4-3275-4d81-8d9c-ff523cd18254
De Francisci, Davide
9d232dd9-241d-4d06-98f7-053227a42012
Guerriero, Gea
4659a0c1-71fd-446b-8d19-3373db103c58
Pilak, Oliver
b7025bf7-7e05-4194-8aae-67b26f977a6f
Burg, Dominic
a51bc2a5-54d3-40ee-ac66-4ca0bc4d9d1d
Raftery, Mark J
a63e7f96-ecfa-4ec7-8f25-367b82e6b7b3
Parkin, Don M
59d5938a-2f68-4008-a8fb-e53981e4f621
Trewhella, Jill
5e106475-ba69-40ea-b1d1-0bbad5a9b01c
Cavicchioli, Ricardo
95c04c14-6cdd-4f0d-afc6-32bdbfa53ad9

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)

Record type: Article

Abstract

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

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e-pub ahead of print date: 9 August 2010
Published date: October 2010
Organisations: Molecular and Cellular

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Local EPrints ID: 338908
URI: http://eprints.soton.ac.uk/id/eprint/338908
ISSN: 1741-0126
PURE UUID: f54a28ce-fae0-4843-9ade-cf3d5385ff18

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Date deposited: 18 May 2012 13:29
Last modified: 14 Mar 2024 11:06

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Contributors

Author: Khawar Sohail Siddiqui
Author: Anne Poljak
Author: Davide De Francisci
Author: Gea Guerriero
Author: Oliver Pilak
Author: Dominic Burg
Author: Mark J Raftery
Author: Don M Parkin
Author: Jill Trewhella
Author: Ricardo Cavicchioli

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