Computational Design of Thermostabilizing d-Amino Acid Substitutions.
Rodriguez-Granillo, A., Annavarapu, S., Zhang, L., Koder, R.L., Nanda, V.(2011) J Am Chem Soc 133: 18750-18759
- PubMed: 21978298 
- DOI: https://doi.org/10.1021/ja205609c
- Primary Citation of Related Structures:  
2LDJ - PubMed Abstract: 
Judicious incorporation of D-amino acids in engineered proteins confers many advantages such as preventing degradation by endogenous proteases and promoting novel structures and functions not accessible to homochiral polypeptides. Glycine to D-alanine substitutions at the carboxy termini can stabilize α-helices by reducing conformational entropy. Beyond alanine, we propose additional side chain effects on the degree of stabilization conferred by D-amino acid substitutions. A detailed, molecular understanding of backbone and side chain interactions is important for developing rational, broadly applicable strategies in using D-amino acids to increase protein thermostability. Insight from structural bioinformatics combined with computational protein design can successfully guide the selection of stabilizing D-amino acid mutations. Substituting a key glycine in the Trp-cage miniprotein with D-Gln dramatically stabilizes the fold without altering the protein backbone. Stabilities of individual substitutions can be understood in terms of the balance of intramolecular forces both at the α-helix C-terminus and throughout the protein.
Organizational Affiliation: 
Department of Biochemistry, Robert Wood Johnson Medical School, University of Medicine and Dentistry of New Jersey (UMDNJ) and Center for Advanced Biotechnology and Medicine, Piscataway, New Jersey 08854, USA.