Open AccessProperties of Basic Amino‐Acid Residues
Author(s) -
WAGNER Karl G.,
ARFMANN HansAdolf
Publication year - 1974
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1974.tb03593.x
Subject(s) - polylysine , chemistry , circular dichroism , nucleotide , cooperativity , crystallography , cooperative binding , stereochemistry , guanine , lysine , stacking , amino acid , binding site , biochemistry , organic chemistry , gene
The interaction of four basic polyamino acids, poly( l ‐lysine), poly( l ‐ornithine), poly( l ‐arginine) and poly( l ‐homoarginine) with nucleotides was investigated using equilibrium dialysis and circular dichroism. Polyhomoarginine was prepared by guanidization of polylysine. The interaction of 5′‐GMP exhibited equal values for the binding cooperativity in all cases, indicating that nucleotide‐nucleotide interaction, i.e. the stacking tendency of the guanine base, was the origin of this affinity. The affinity parameters of 5′‐GMP and other nucleotides directed towards the basic polypeptides, however, decrease in the series: polyarginine > polyhomoarginine > polyornithine > polylysine. This indicates that the ion bond between guanidinium and phosphate is stronger than that between ammonium and phosphate, and that decreasing the length of the poly(amino acid) side chains by one CH 2 group results in an increase of affinity. The binding of 3′‐GMP and 5′‐GMP by polylysine and polyornithine induces a strong negative circular dichroism band in the absorption region of the base and in the case of polylysine also changes at shorter wavelength. Temperature‐dependent measurements of these circular dichroic spectra revealed that polylysine fits best to and forms the most stable complexes with helical arrangements of bound GMP molecules.