1UNO

Crystal structure of a d,l-alternating peptide

Summary for 1UNO

• Entry DOI: 10.2210/pdb1uno/pdb
• Related PRD ID: PRD_000107
• Descriptor: H-(L-TYR-D-TYR)4-LYS-OH (2 entities in total)
• Functional Keywords: d-l peptide, d, l-alternating peptide, beta-helix
• Biological source: SYNTHETIC CONSTRUCT
• Total number of polymer chains: 2
• Total formula weight: 2905.17

Authors

Alexopoulos, E.,Kuesel, A.,Uson, I.,Diederichsen, U.,Sheldrick, G.M. (deposition date: 2003-09-11, release date: 2004-09-24, Last modification date: 2024-10-23)

Primary citation

Alexopoulos, E.,Kuesel, A.,Sheldrick, G.M.,Diederichsen, U.,Uson, I.
Solution and Structure of an Alternating D,L-Peptide
Acta Crystallogr.,Sect.D, 60:1971-, 2004

PubMed Abstract: The crystal structure of H-(L-Tyr-D-Tyr)(4)-L-Lys-OH has been determined to 1.3 A resolution. The D,L-alternating peptide crystallizes in the tetragonal system, space group P4(3)2(1)2, with unit-cell parameters a = b = 27.99 (3), c = 78.93 (8) A. The crystals contain two molecules in the asymmetric unit that form a double-stranded right-handed antiparallel beta-helix. The structure has been solved by SIRAS using a crystal soaked in an iodide-containing solution for 1 min. The programs SHELXD and SHELXE were used to determine the iodide substructure and also the experimental electron-density map. Using the coordinates of known D,L-peptides deposited in the PDB, several attempts were made to solve the structure by molecular-replacement techniques. Although the backbone of the MR model selected shows great similarity and was used to trace the actual peptide structure in the map, it was not possible to obtain the correct solution before the experimental phases became available. The correct fragment orientations are easily determined, but the same does not apply to the translation search. Nevertheless, insights into fragment search and expansion were gained from the tests described in this paper. The correlation coefficient calculated with the resolution shell of data around 2.4 A, a distance corresponding to most 1-3 interatomic vectors, is a particularly good discriminator of correct orientations in the rotation search of small fragments.

PubMed: 15502304
DOI: 10.1107/S0907444904022292

Experimental method

X-RAY DIFFRACTION (1.4 Å)