Download MendeleyFunctional implications of structural differences between variants A and B of bovine beta-lactoglobulin.
Qin, B.Y., Bewley, M.C., Creamer, L.K., Baker, E.N., Jameson, G.B.(1999) Protein Sci 8: 75-83
- PubMed: 10210185
- DOI: https://doi.org/10.1110/ps.8.1.75
- Primary Citation of Related Structures:
1BSQ - PubMed Abstract:
The structure of the trigonal crystal form of bovine beta-lactoglobulin variant B at pH 7.1 has been determined by X-ray diffraction methods at a resolution of 2.22 A and refined to values for R and Rfree of 0.239 and 0.286, respectively. By comparison with the structure of the trigonal crystal form of bovine beta-lactoglobulin variant A at pH 7.1, which was determined previously [Qin BY et al., 1998, Biochemistry 37:14014-14023], the structural consequences of the sequence differences D64G and V118A of variants A and B, respectively, have been investigated. Only minor differences in the core calyx structure occur. In the vicinity of the mutation site D64G on loop CD (residues 61-67), there are small changes in main-chain conformation, whereas the substitution V118A on beta-strand H is unaccompanied by changes in the surrounding structure, thereby creating a void volume and weakened hydrophobic interactions with a consequent loss of thermal stability relative to variant A. A conformational difference is found for the loop EF, implicated in the pH-dependent conformational change known as the Tanford transition, but it is not clear whether this reflects differences intrinsic to the variants in solution or differences in crystallization.
Organizational Affiliation:
Centre for Structural Biology, Institute of Fundamental Sciences, Massey University, Palmerston North, New Zealand.
