Crystal structure and conformational analysis of angiotensinogen fragments
| Autor: | Gilles Precigoux, Michel Cotrait, S. Geoffre, M. Benkoulouche |
|---|---|
| Rok vydání: | 2009 |
| Předmět: |
Crystallography
Protein Conformation Stereochemistry Hydrogen bond Molecular Sequence Data Angiotensinogen Hydrogen Bonding Tripeptide Crystal structure Biochemistry Peptide Fragments chemistry.chemical_compound Protein structure chemistry Zwitterion Side chain Thermodynamics Orthorhombic crystal system Amino Acid Sequence Conformational isomerism |
| Zdroj: | International Journal of Peptide and Protein Research. 34:463-470 |
| ISSN: | 0367-8377 |
| Popis: | The tripeptide acetyl-L-prolyl-L-phenylalanyl-L-histidine crystallizes in the orthorhombic space group P2(1)2(1)2(1) with eight molecules in a unit cell of dimensions a = 9.028(2), b = 140.54(6) and c = 42.41(1)A. The structure has been solved by direct methods and refined to an R value of 0.056 for 2904 observed reflections. The molecule exists as a zwitterion with terminal (His)CO2- and (imidazole)H+ as charged groups. The two peptide molecules in the structure adopt a type I beta-turn with Pro and Phe as the corner residues. The main conformational difference between the two crystallographically independent molecules is seen to be in the histidine side-chain orientations. The molecules arrange themselves in sheets perpendicular to the c axis. All hydrophobic side chains lie on one side of the sheets thus generated, whereas the hydrophilic groups are located on the other side. An interesting feature of the crystal structure is the existence of a water layer between adjacent peptide sheets. The conformational study of the isolated Ac-His-Pro-Phe-His-MA using energy calculations gives a rather limited number of stable conformers. The most stable corresponds to a type I beta-turn stabilized through two hydrogen bonds, followed by a less stable type II beta-turn (delta E = 2.0 kcal) and a partly helical structure (delta E = 2.6 kcal). |
| Databáze: | OpenAIRE |
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