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Helix capping
Author(s) -
Aurora Rajeev,
Rosee George D.
Publication year - 1998
Publication title -
protein science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.353
H-Index - 175
eISSN - 1469-896X
pISSN - 0961-8368
DOI - 10.1002/pro.5560070103
Subject(s) - hydrogen bond , helix (gastropod) , crystallography , chemistry , alpha helix , protein structure , structural motif , protein secondary structure , stereochemistry , circular dichroism , biology , molecule , biochemistry , ecology , organic chemistry , snail
Helix‐capping motifs are specific patterns of hydrogen bonding and hydrophobic interactions found at or near the ends of helices in both proteins and peptides. In an α‐helix, the first four >N‐H groups and last four >C=O groups necessarily lack intrahelical hydrogen bonds. Instead, such groups are often capped by alternative hydrogen bond partners. This review enlarges our earlier hypothesis (Presta LG, Rose GD. 1988. Helix signals in proteins. Science 240 :1632‐1641) to include hydrophobic capping. A hydrophobic interaction that straddles the helix terminus is always associated with hydrogen‐bonded capping. From a global survey among proteins of known structure, seven distinct capping motifs are identified‐three at the helix N‐terminus and four at the C‐terminus. The consensus sequence patterns of these seven motifs, together with results from simple molecular modeling, are used to formulate useful rules of thumb for helix termination. Finally, we examine the role of helix capping as a bridge linking the conformation of secondary structure to supersecondary structure.