Racemic crystallography of synthetic protein enantiomers used to determine the X-ray structure of plectasin by direct methods
We describe the use of racemic crystallography to determine the X-ray structure of the natural product plectasin, a potent antimicrobial protein recently isolated from fungus. The protein enantiomers L-plectasin and D-plectasin were prepared by total chemical synthesis; interestingly, L-plectasin showed the expected antimicrobial activity, while D-plectasin was devoid of such activity. The mirror image proteins were then used for racemic crystallization. Synchrotron X-ray diffraction data were collected to atomic resolution from a racemic plectasin crystal; the racemate crystallized in the achiral centrosymmetric space group P1 with one L-plectasin molecule and one D-plectasin molecule forming the unit cell. Dimer-like intermolecular interactions between the protein enantiomers were observed, which may account for the observed extremely low solvent content (13%-15%) and more highly ordered nature of the racemic crystals. The structure of the plectasin molecule was well defined for all 40 amino acids and was generally similar to the previously determined NMR structure, suggesting minimal impact of the crystal packing on the plectasin conformation.
- Research Organization:
- Argonne National Lab. (ANL), Argonne, IL (United States)
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 1005702
- Journal Information:
- Protein Sci., Vol. 18, Issue (6) ; 2009
- Country of Publication:
- United States
- Language:
- ENGLISH
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Related Subjects
99 GENERAL AND MISCELLANEOUS//MATHEMATICS, COMPUTING, AND INFORMATION SCIENCE
AMINO ACIDS
CRYSTALLIZATION
CRYSTALLOGRAPHY
CRYSTALS
DATA
IMAGES
INTERACTIONS
MIRRORS
MOLECULES
NUCLEAR MAGNETIC RESONANCE
PROTEINS
RACEMATES
RESOLUTION
SOLVENTS
SPACE GROUPS
SYNTHESIS
X-RAY DIFFRACTION