title: Peptide crystal growth via vapor diffusion. Crystal structure of glycyl-L-tyrosyl-L-alanine dihydrate.
abstract: The structure of a dihydrated form of glycyl-L-tyrosyl-L-alanine (GYA) has been determined as part of a series of peptide structural investigations and development of microscale vapor diffusion experiments for peptide crystal growth. Crystals were grown by the hanging-drop method against sodium acetate. The tripeptide is a zwitterion in the crystal, adopting an extended conformation through glycine, a nearly perpendicular bend at tyrosine and a reverse turn for the C-terminal carboxylate. Principal backbone torsion angles are psi 1 175(1) degrees, omega 2 173(1) degrees, phi 2 -119(1) degrees, psi 2 120(1) degrees, omega 3 172(1) degrees, phi 3 -73(1) degrees, psi 31 -9(1) degrees, psi 32 171(1) degrees. The tyrosyl side chain adopts an unusual orientation (chi 1/2 = -86(1) degrees). The relationship of the GYA.2H2O structure to GYA sequences in proteins is examined, particularly as regards its helix-forming potential. Crystal data: C14H19N3O4.2H2O, M(r) = 345.36, orthorhombic, P2(1)2(1)2(1), a = 4.810 (4), b = 11.400(7), c = 30.162(23)A, V = 1653.8(24)A-3, Z = 4, Dx = 1.387 Mgm-3, lambda(CuK- alpha) = 1.540 A, mu = 9.053 mm-1, F(000) = 736, T = 199 K, R = 0.041 for 1458 observations with I greater than or equal to 3 sigma(I).
authors.affiliation: SmithKline Beecham Pharmaceuticals, King of Prussia, PA.
authors.forename: D S
authors.initials: DS
authors.lastname: Eggleston
authors.forename: P W
authors.initials: PW
authors.lastname: Baures
mesh_terms: D000595:Amino Acid Sequence; D003460:Crystallization; D004058:Diffusion; D008969:Molecular Sequence Data; D009842:Oligopeptides / Q000737:chemistry*; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D014961:X-Ray Diffraction
chemical_list: D009842:Oligopeptides; C078139:glycyl-tyrosyl-alanine