Analysis of distribution of alternating-sign charged clusters on the surface of globular proteins
Larionova, E.A.; Chirgadze, I.N.
Molekuliarnaia Biologiia 32(6): 1020-1024
1998
ISSN/ISBN: 0026-8984 PMID: 9929880 Document Number: 488832
Sign-alternating charge clusters consisting of charged side and terminal chains of amino acid residues exist on the surface of globular proteins. Charge clusters are determined on the basis of distance between charged structures. One hundred and nineteen nonhomologous proteins from the Protein Structure Bank were considered. Clusters containing four or more charged groups were observed in 83.5% of the proteins. Theoretical assessment of the distribution of sign-alternating charge clusters of various sizes was conducted on the basis of the probability model of charge distribution. It was found that the distribution of isolated charged groups, small clusters, and large clusters with 4-6 groups complied with the requirements of the statistics of random distribution of non-branched clusters. At the same time, giant charge clusters with seven or more groups were observed in proteins much more frequently than according to random distribution. The functional role of sign-alternating charge clusters was discussed. Apparently, their principal role is to determine the local stability of individual surface elements and consequently the three-dimensional native structure of globular proteins.