Russian Journal of Bioorganic Chemistry, Vol. 23, No. 4, 1997, p. 223

Novel Structural Motifs in -Helical Proteins

A. V. Efimov ¹

Institute of Protein Research , Russian Academy of Sciences, Pushchino, 142292, Moscow oblast, Russia

Abstract: Four novel structural motifs were found and characterized in -helical proteins. One of them consists of three helices and can be represented as a combination of an – corner and an L-shaped structure. Its second helix is a part of both one of the two helices of the – corner and one of the two L-structure helices. The second structural motif, named the ABCD unit, consists of four helices, A, B, C, and D. These are consecutive in sequence and arranged in space in such a manner that the helices B, C, and D form a left-handed superhelix and the helix A is located between the helices B and D and is approximately antiparallel to them. The third motif, helix–loop– helix, consists of two helices and a long connection. Its helices are arranged in an approximately parallel manner and, together with the long connection, form a left-handed –l– superhelix in space. The fourth structural motif considered is formed by four consecutive helices. It is named the motif, because its overall shape is reminiscent of the Greek letter . Various variants of these motifs are analyzed on numerous examples of proteins with the known spatial structures.

Key words: proteins, spatial structure; – corner, – hairpin, L-structure, left- and right-handed superhelix, stereochemical analysis