66 results about "X-ray crystallography" patented technology

The mechanism of the UV light-induced reaction between the indole moiety of tryptophan and chloroform, and the structure of the modified tryptophan and polypeptides including such modified tryptophan residues. The excited indole moiety, which is formed upon UV light irradiation, emits a solvated electron which initiates a series of events that yield fluorescent derivatives that have CHO group covalently bound to the indole moiety. These derivatives are herein referred to as formyltryptophan, and are relatively stable. Similar reactions are observed when 5-hydroxytryptophan, 5-fluorotryptophan, or N-methylindolacetate are used in place of tryptophan, or when other haloalkanes, such as trichloracetic acid, trichlorethanol, trichlorethane, bromoform, and iodoactetate are used in place of chloroform. The derivatives can be used in a variety of applications in fluorescence spectroscopy, and for nuclear magnetic resonance, X-ray crystallography, infra-red spectroscopy, circular dicroism and mass spectroscopy. Additionally, the UV light-induced reaction between the indole moiety of tryptophan and haloalkanes can be used to prepare derivatives of tryptophan for chemical cross-linking studies of proteins and peptides.

The three-dimensional structure of crystalline pertussis holotoxin (PT) has been determined by X-ray crystallography. Crystal structures have also been determined for complexes of pertussis toxin with molecules relevant to the biological activity of PT. These three-dimensional structures were analyzed to identify functional amino acids appropriate for modification to alter the biological properties of PT. Similar procedures may be used to predict amino acids which contribute to the toxicity of the holotoxin, to produce immunoprotective, genetically-detoxified analogs of pertussis toxin.

The invention is a crystallization cassette and associated method for growing and analyzing macromolecular crystals in situ by X-ray crystallography. The cassette allows proteins (as well as other macromolecules) to be crystallized by the counter-diffusion method in a restricted geometry. Using this procedure, crystals can be adequately prepared for direct X-ray data analysis such that the protein's three-dimesional structure can be solved without crystal manipulation.

Sample mounts (10) for mounting microcrystals of biological macromolecules for X-ray crystallography are prepared by using patterned thin polyimide films (12) that have curvature imparted thereto, for example, by being attached to a curved outer surface of a small metal rod (16). The patterned film (12) preferably includes a tapered tip end (24) for holding a crystal. Preferably, a small sample aperture is disposed in the film for reception of the crystal. A second, larger aperture can also be provided that is connected to the sample aperture by a drainage channel, allowing removal of excess liquid and easier manipulation in viscous solutions. The curvature imparted to the film (12) increases the film's rigidity and allows a convenient scoop-like action for retrieving crystals. The polyimide contributes minimally to background and absorption, and can be treated to obtain desired hydrophobicity or hydrophilicity.

The structures of Edema Factor alone and Edema Factor bound to calmodulin without substrate has been crystallized and its structure determined by x-ray crystallography. Based upon these crystal structures, a method assaying for inhibitors of infection by a bacteria is presented which comprises obtaining a potential inhibitor, obtaining a calmodulin activated adenylyl cyclase exotoxin, obtaining calmodulin, admixing the potential inhibitor, the exotoxin, and the calmodulin, and assaying to determine whether or not the potential inhibitor inhibits production of cAMP by exotoxin.