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Mutation Choice to Eliminate Buried Free Cysteines in Protein Therapeutics

Title: Mutation Choice to Eliminate Buried Free Cysteines in Protein Therapeutics .
Name(s): Xia, Xue, author
Longo, Liam, author
Blaber, Michael, author
Type of Resource: text
Genre: text
Date Issued: 2014-10-13
Physical Form: computer
Physical Form: online resource
Extent: 1 online resource
Language(s): English
Abstract/Description: Buried free Cys residues can contribute to an irreversible unfolding pathway that promotes protein aggregation, increases immunogenic potential, and significantly reduces protein functional half-life. Consequently, mutation of buried free Cys residues can result in significant improvement in the storage, reconstitution, and pharmacokinetic properties of protein-based therapeutics. Mutational design to eliminate buried free Cys residues typically follows one of two common heuristics: either substitution by Ser (polar and isosteric), or substitution by Ala or Val (hydrophobic); however, a detailed structural and thermodynamic understanding of Cys mutations is lacking. We report a comprehensive structure and stability study of Ala, Ser, Thr and Val mutations at each of the three buried free Cys positions (Cys16, Cys83, and Cys117) in fibroblast growth factor-1 (FGF-1). Mutation was almost universally destabilizing, indicating a general optimization for the wild-type Cys, including van der Waals and H-bond interactions. Structural response to Cys mutation characteristically involved changes to maintain, or effectively substitute, local H-bond interactions -- by either structural collapse to accommodate the smaller oxygen radius of Ser/Thr, or conversely, expansion to enable inclusion of novel H-bonding solvent. Despite the diverse structural effects, the least destabilizing average substitution at each position was Ala, and not isosteric Ser.
Identifier: FSU_libsubv1_scholarship_submission_1456504649 (IID), 10.1002/jps.24188 (DOI)
Keywords: Protein aggregation, protein structure, stability, crystal structure, thermodynamics, protein engineering, protein half-life, hydrogen bond, fibroblast growth factor-1
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Owner Institution: FSU
Is Part Of: Journal of Pharmaceutical Sciences.
Issue: iss. 2, vol. 104