Creative Biostructure is a pioneer in the field of peptide crystallization and have rich experience in determining the structure of small peptides and their complexes with proteins.
IntroductionPeptides consist of short amino acid chains, mostly without well-defined conformation in solution (except cyclic peptides). Like many other flexible small molecules, peptides can be crystallized under appropriate conditions, where they can have reasonable and stable conformation and retain their native structures and functions.
The main purpose of peptide crystallization is to produce well-ordered crystals with uniform content. Peptide purity is an important parameter before crystallization. The presence of various contaminations makes crystals almost unsuitable for X-ray diffraction and analysis. Only a few peptides can form crystals from the mixture of different peptides and amino acids. Due to this property, crystallization is sometimes used as a peptide purification technique. For most cases the purity of peptide should be no less than 95%. Several peptides adopt stable conformations by adding extra compounds like metal ions, such as cyclic peptide antibiotics (e.g., Valinomycin). In this case, it is very important to use proper compounds to obtain crystals with preferred peptide conformations. The size of crystals is also crucial, which should be large enough and well-packaged to diffract X-ray with detectable pattern of diffraction, while small enough to avoid any possible distortion. The optimal size for peptide crystals is about 0.2-1.0 mm.