Chimeric Protein Engineering

• Published in: International journal of peptide research and therapeutics Vol. 13; no. 1-2; pp. 151 - 160
• Main Authors: Feng, Jianwen A, Tessler, Lee A, Marshall, Garland R
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Nature B.V 01.06.2007
• Subjects: Amino acid sequence; Denaturation; Design; Enzymatic activity; Enzymes; HIV; Human immunodeficiency virus; Hydrogen bonding; Molecular dynamics; N-Terminus; Peptidomimetics; Protein engineering; Protein folding; Proteins; Proteolysis; Ribonuclease A
• ISSN: 1573-3149; 1573-3904
• DOI: 10.1007/s10989-006-9058-8

Protein stability can be enhanced by the incorporation of non-natural amino acids and semi-rigid peptidomimetics to lower the entropic penalty upon protein folding through preorganization. An example is the incorporation of aminoisobutyric acid (Aib, α-methylalanine) into proteins to restrict the Φ and Ψ backbone angles adjacent to Aib to those associated with helix formation. Reverse-turn analogs were introduced into the sequences of HIV protease and ribonuclease A that enhanced their stability and retained their native enzymatic activity. In this work, a chimeric protein, design_4, was engineered, in silico, by replacing the C-terminal helix of full sequence design protein (FSD-1) with a semi-rigid helix mimetic. Residues 1–16 of FSD-1 was ligated in silico with the N-terminus of a phenylbipyridyl-based helix mimetic to form design_4. The designed chimeric protein was stable and maintained the designed fold in a 100-nanosecond molecular dynamics simulation at 280 K. Its β-hairpin adopted conformations that formed three additional hydrogen bonds. Compared to FSD-1, design_4 contained fewer peptide bonds and internal degrees of freedom; it should, therefore, be more resistant to proteolytic degradation and denaturation.