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. Study holds ProTherm entries: 25787, 25788, 25789, 25790, 25791, 25792, 25793, 25794 Extra Details: Unfolding at a scan rate of 60 degreesC/h activation thermodynamics; calorimetry; entropy/ enzyme kinetics; protein X-ray crystallographic structure

Submission Details

ID: goATrosq3

Submitter: Connie Wang

Submission Date: April 24, 2018, 8:56 p.m.

Version: 1

Publication Details
Siddiqui KS;Poljak A;De Francisci D;Guerriero G;Pilak O;Burg D;Raftery MJ;Parkin DM;Trewhella J;Cavicchioli R,Protein Eng. Des. Sel. (2010) A chemically modified alpha-amylase with a molten-globule state has entropically driven enhanced thermal stability. PMID:20696745
Additional Information

Structure view and single mutant data analysis

Study data

No weblogo for data of varying length.
Colors: D E R H K S T N Q A V I L M F Y W C G P

Data Distribution

Studies with similar sequences (approximate matches)

Correlation with other assays (exact sequence matches)

Relevant UniProtKB Entries

Percent Identity Matching Chains Protein Accession Entry Name
100.0 Alpha-amylase A type-1/2 P0C1B3 AMYA1_ASPOR
94.6 Alpha-amylase A type-1/2 Q02906 AMYB_ASPAW
99.8 Alpha-amylase A type-1/2 P30292 AMY_ASPSH
99.6 Alpha-amylase A type-1/2 P0C1B4 AMYA3_ASPOR
94.6 Alpha-amylase A type-1/2 Q02905 AMYA_ASPAW