1qig: Difference between revisions

Radiation damage is an inherent problem in x-ray crystallography. It, usually is presumed to be nonspecific and manifested as a gradual decay in, the overall quality of data obtained for a given crystal as data, collection proceeds. Based on third-generation synchrotron x-ray data, collected at cryogenic temperatures, we show for the enzymes Torpedo, californica acetylcholinesterase and hen egg white lysozyme that, synchrotron radiation also can cause highly specific damage. Disulfide, bridges break, and carboxyl groups of acidic residues lose their, definition. Highly exposed carboxyls, and those in the active site of both, enzymes, appear particularly susceptible. The catalytic triad residue, His-440, in acetylcholinesterase, also appears to be much more sensitive, to radiation damage than other histidine residues. Our findings have, direct practical implications for routine x-ray data collection at, high-energy synchrotron sources. Furthermore, they provide a direct, approach for studying the radiation chemistry of proteins and nucleic, acids at a detailed, structural level and also may yield information, concerning putative "weak links" in a given biological macromolecule, which may be of structural and functional significance.

1QIG is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Torpedo_californica Torpedo californica]. Active as [http://en.wikipedia.org/wiki/Acetylcholinesterase Acetylcholinesterase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=3.1.1.7 3.1.1.7] Structure known Active Site: CAT. Full crystallographic information is available from [http://ispc.weizmann.ac.il/oca-bin/ocashort?id=1QIG OCA].  

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