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Synthesis and Conformational Studies of Model Histones: II Sequential and Random Polypeptides with the Composition L‐Lysyl:L‐Alanyl:L‐Proline
Author(s) -
Cernosek Stanley F.,
Wells Margarete,
Fasman Gerald D.
Publication year - 1974
Publication title -
israel journal of chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.908
H-Index - 54
eISSN - 1869-5868
pISSN - 0021-2148
DOI - 10.1002/ijch.197400007
Subject(s) - chemistry , random coil , polymer , aqueous solution , polymerization , helix (gastropod) , sequence (biology) , amino acid , crystallography , stereochemistry , kinetics , protein secondary structure , composition (language) , lysine , circular dichroism , biochemistry , organic chemistry , ecology , physics , quantum mechanics , snail , biology , linguistics , philosophy
The sequential polytripeptide (Lys‐Ala‐Pro) n and the random polypeptide (Lys 36.2 Ala 32.5 Pro 31.3 ) n were synthesized as model histones to be used in studying the structure and interactions of nucleohistone complexes. The CD spectra of (Lys‐Ala‐Pro) n in aqueous solutions, at both pH 7 and 11, as well as in HFIP, TFA, and 1 M SDS (pH 7), indicated that this polytripeptide only assumed the random coil conformation under all these conditions. In aqueous solution, the CD spectra of the random sequence polypeptide indicated that this polymer undergoes a pH‐dependent random coil‐helix transition as the pH is raised from 7 to 11. This polymer was also partially helical in TFE. The observation that the random polymer can assume a regular, asymmetric structure may be due to a clustering of lysyl and alanyl residues at one end of the polymer because of the faster incorporation of Pro than Lys or Ala, as indicated by their respective kinetics of polymerization. The random conformation of the sequential polypeptide, (Lys‐Ala‐Pro) n , is probably determined by the presence of Pro at regular intervals. It is concluded that the sequential polymer (Lys‐Ala‐Pro) n is a plausible model histone for use in studying the influence of amino acid sequence and composition on the structure and interactions of nucleohistone complexes.