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Ion pairs in alpha helices
Author(s) -
Sundaralingam M.,
Sekharudu Y.C.,
Yathindra N.,
Ravichandran V.
Publication year - 1987
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.340020108
Subject(s) - ion , globular protein , alpha (finance) , folding (dsp implementation) , alpha helix , chemistry , beta (programming language) , crystallography , helix (gastropod) , protein folding , physics , circular dichroism , biology , mathematics , biochemistry , statistics , computer science , ecology , construct validity , organic chemistry , snail , electrical engineering , engineering , psychometrics , programming language
A survey of 47 globular proteins was made to determine the probability of occurrence of ion pairs separated by 1, 2, 3, … and 8 residues in the alpha helices. As a control, the probability of occurrence of like charged pairs was also determined. The survey showed that ion pairs of the type i, i±3 and i, i±4 are the most predominant. Such a preference was not observed for like charged pairs. The observed frequency of ion pairs is significantly greater than their expected frequency. The normalized frequencies of occurrence of the ion pairs were also found to increase generally with the helix length. These results indicate that the ion pairs may contribute to the stability of solvent‐exposed alpha helices. Since the stabilization of protein secondary structure, these results may throw light on the mechanism of protein folding.