Okamura TA, Tsubouchi K, Onitsuka K. Zigzag-Helix Transformation of Expanded Polyvaline Induced by Racemization.
Chem Asian J 2019;
14:2950-2952. [PMID:
31318486 DOI:
10.1002/asia.201900896]
[Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2019] [Revised: 07/18/2019] [Indexed: 12/25/2022]
Abstract
Biological macromolecules are essentially homochiral. For example, proteins mostly consist of l-amino acids. What happens when a chiral molecule meets itself in a mirror? For expanded polyvaline, zigzag-helix transformation occurs. In this study, expanded polyvalines containing bis(pyridine)silver(I) moieties were synthesized and isolated as single crystals. The molecular structures were determined by X-ray analysis, which revealed that chiral expanded poly(l-valine) and poly(d-valine) form zigzag chains. However, racemic mixture of these molecules form left- and right-handed 41 helices that retain the original sequences. These secondary structures can be transformed by only flipping the C-terminal amide plane for each unit, which is reminiscent of the relationship between an α-helix and a β-strand. Such expanded polypeptides can be built up into expanded protein, forming a tailor-made three-dimensional structure, which will lead to new functions.
Collapse