# Protein thermal stability: insights from atomic displacement parameters (B values)

Parthasarathy, S and Murthy, MRN (2000) Protein thermal stability: insights from atomic displacement parameters (B values). In: Protein Engineering, 13 (1). pp. 9-13.

 PDF Protein_thermal_stability.pdf Restricted to Registered users only Download (104Kb) | Request a copy

## Abstract

The factors contributing to the thermal stability of proteins from thermophilic origins are matters of intense debate and investigation. Thermophilic proteins are thought to possess better packed interiors than their mesophilic counterparts, leading to lesser overall flexibility and a corresponding reduction in surface-to-volume ratio. These observations prompted an analysis of B values reported in high-resolution X-ray crystal structures of mesophilic and thermophilic proteins. In this analysis, the following aspects were addressed: (1) frequency distribution of normalized B values (B' factors) over all the proteins and for individual amino acids; (2) amino acid compositions in high B value regions of polypeptide chains; (3) variation in the B values from core to the surface of proteins in terms of their radius of gyration; and (4) degree of dispersion of normalized B values in spheres around the $C\alpha$ atoms. The analysis revealed that (1) Ser and Thr have lesser flexibility in thermophiles than in mesophiles, (2) the proportion of Glu and Lys in high B value regions of thermophiles is higher and that of Ser and Thr is lower and (3) the dispersion of B values within spheres at $C\alpha$ atoms is similar in mesophiles and thermophiles. These observations reflect plausible differences in the dynamics of thermophilic and mesophilic proteins and suggest amino acid substitutions that are likely to change thermal stability.

Item Type: Journal Article Copyright of this article belongs to Oxford University Press. Protein dynamics;Protein stability;Temperature factors;Thermophiles;X-ray structures Division of Biological Sciences > Molecular Biophysics Unit 15 Oct 2007 19 Sep 2010 04:39 http://eprints.iisc.ernet.in/id/eprint/12013