A sequence preference for nucleation of α-helix—crystal structure of Gly-L-Ala-L-Val and Gly-L-Ala-L-Leu: Some comments on the geometry of leucine zippers

✍ Scribed by Sanjeev Chaturvedi; Kuantee Go; R. Parthasarathy

• Publisher: Wiley (John Wiley & Sons)
• Year: 1991
• Tongue: English
• Weight: 723 KB
• Volume: 31
• Category: Article
• ISSN: 0006-3525
• DOI: 10.1002/bip.360310405

✦ Synopsis

The synthetic peptide Gly-L-Ala-L-Val ( CloH19N,0, * 3H20; GAV) crystallizes in the monoclinic space group P21, with a = 8.052( 2), b = 6.032(2), c = 15.779(7) A, ( 3 = 98.520( l)', V = 757.8 A3, D, = 1.312 g ~m -~, and 2 = 2. The peptide Gly-L-Ala-L-Leu ( C,,HplN30, * 3H20; GAL) crystallizes in the orthorhombic space group P2,2,2,, with a = 6 . 0 2 4 ( 1 ) , b = 8 . 1 7 1 ( 1 ) , ~= 3 2 . 7 9 1 ( 1 ) ~, V = 1 6 1 4 A 3 , D , = 1 . 2 8 9 g ~m -~, a n d . Z = 4 . Their crystal structures were solved by direct methods using the program SHELXS-86, and refined to an R index of 0.05 for 1489 reflections for GAV and to an R index of 0.05 for 1563 reflections for GAL. The tripeptides exist as a zwitterion in the crystal and assume a near a-helical backbone conformation with the following torsion angles: $1 = -150.7';