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Ion pair formation involving methylated lysine side chains: A theoretical study
Author(s) -
Mavri Janez,
Vogel Hans J.
Publication year - 1994
Publication title -
proteins: structure, function, and bioinformatics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.699
H-Index - 191
eISSN - 1097-0134
pISSN - 0887-3585
DOI - 10.1002/prot.340180408
Subject(s) - chemistry , methylamine , formate , ethylamine , lysine , side chain , interaction energy , ab initio , computational chemistry , methyl group , carboxylate , stereochemistry , amino acid , organic chemistry , molecule , group (periodic table) , biochemistry , polymer , catalysis
Lysine residues with one, two, or three methyl groups substituted on the ϵ‐nitrogen atom are found in many proteins. To evaluate the effect of the posttranslational methylation on ion‐pair formation we have performed semiempirical and ab initio molecular orbital calculations, using the AMI method and the 6‐31G * basis set, respectively. Combinations of various methylated forms of methylamine and ethylamine with formate, acetate, and dimethyl phosphate were studied as model compounds. This approach allowed us to obtain information relevant to the interaction of the modified Lys residues with carboxylate groups of proteins, and the backbone of nucleic acids. We have found that the interaction energy decreases with an increasing number of methyl groups. Inclusion of a solvent reaction field in the semiempirical calculations gave reasonable values for the interaction energy in aqueous solution, when formate and acetate were the counterions. These studies suggest that, in addition to other factors, a weakening of ionic interactions contributes to the various physiological effects of lysine methylation. © 1994 John Wiley & Sons, Inc.