3al1

DESIGNED PEPTIDE ALPHA-1, RACEMIC P1BAR FORM

spinqualitylabelsall models 3al1, resolution 0.75Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 3al1 is a 2 chain structure. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 0.75Å Ligands: ACE, ETA, MPD Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Publication Abstract from PubMed We report the 0.75 A crystal structure of a racemic mixture of the 12-residue designed peptide "Alpha-1" (Acetyl-ELLKKLLEELKG), the L-enantiomer of which is described in the accompanying paper. Equivalent solutions of the centrosymmetric bilayers were determined by two direct phasing programs in space groups P1 and P1bar. The unit cell contains two L-alpha-helices and two D-alpha-helices. The columnar-sheet bilayer motif seen in L-Alpha-1 is maintained in the D,L-Alpha-1 structure except that each sheet of head-to-tail helices is composed of one enantiomer and is related to its neighboring sheets by inversion symmetry. Comparison to the L-Alpha-1 structure provides further insight into peptide design. The high resolution and small asymmetric unit allowed building an intricate model (R = 13.1%, Rfree = 14.5%) that incorporates much of the discrete disorder of peptide and solvent. Ethanolamine and 2-methyl-2,4-pentanediol (MPD) molecules bind near helix termini. Rigid body analysis identifies sites of restricted displacements and torsions. Side-chain discrete disorder propagates into the backbone of one helix but not the other. Although no side chain in Alpha-1 is rigid, the environments in the crystal restrict some of them to no or only one active torsion. Centrosymmetric bilayers in the 0.75 A resolution structure of a designed alpha-helical peptide, D,L-Alpha-1.,Patterson WR, Anderson DH, DeGrado WF, Cascio D, Eisenberg D Protein Sci. 1999 Jul;8(7):1410-22. PMID:10422829 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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