| 摘要： |
A combined experimental and computational study is performed for arginine side chain stacking with the protein -helix. Theremostability measurements of Aristaless homeodomain, a helical protein, suggest that mutating the arginine residue R106, R137 or R141, which has the guanidino side chain stacking with the peptide plane, to alanine, destabilizes the protein. The R-PP stacking has an energy of approximate to 0.2-0.4 kcal/mol. This stacking interaction mainly comes from dispersion and electrostatics, based on MP2 calculations with the energy decomposition analysis. The calculations also suggest that the stacking stabilizes 2 backbone-backbone h-bonds (ii-4 and i-3i-7) in a cooperative way. Desolvation and electrostatic polarization are responsible for cooperativity with the ii-4 and i-3i-7 h-bonds, respectively. This cooperativity is supported by a protein -helices h-bond survey in the pdb databank where stacking shortens the corresponding h-bond distances. |
