Residual electrostatic effects in the unfolded state of the N-terminal domain of L9 can be attributed to nonspecific nonlocal charge-charge interactions.
Residual electrostatic interactions in the unfolded state of the N-terminal domain of L9 (NTL9) were found by Kuhlman et al. [(1999) Biochemistry 38, 4896-4903]. These residual interactions are analyzed here by the Gaussian-chain model [Zhou, H.-X. (2002) Proc. Natl. Acad. Sci. U.S.A. 99, 3569-3574]. The original model is made more realistic by replacing "standard" model-compound pK(a) values for ionizable groups by those measured by Kuhlman et al. in peptide fragments of NTL9. The predicted pH dependence of the unfolding free energy is in agreement with experiment over the pH range of 1-7 at ionic strengths of 100 and 750 mM. This indicates that the residual electrostatic effects in the unfolded state of NTL9 can be attributed to nonspecific nonlocal charge-charge interactions.
Zhou
Huan-Xiang
HX
Department of Physics, Drexel University, Philadelphia, Pennsylvania 19104, USA. zhou@sb.fsu.edu
D000595:Amino Acid Sequence; D006863:Hydrogen-Ion Concentration; D008956:Models, Chemical; D008969:Molecular Sequence Data; D016011:Normal Distribution; D010446:Peptide Fragments / Q000737:chemistry*; D011489:Protein Denaturation; D017510:Protein Folding; D017434:Protein Structure, Tertiary; D012269:Ribosomal Proteins / Q000737:chemistry*; D055672:Static Electricity
D010446:Peptide Fragments; D012269:Ribosomal Proteins; C049650:ribosomal protein L9