Crystal structure degradation

Problems stUl remain, though, in this area of endeavour. Any destruction of the perfection in the crystal structure degrades the sharpness of the diffracted beams. This in itself can be used for crystallite size determination. Poorly crystalline material gives poor information, and truly amorphous samples give virtually no crystallographic information this way. 

Cell performance decay on cycling results from the following causes (1) anode crystal structure degradation [45-47], (2) cathode crystal structure degradation [22,48-50], (3) electrode/electrolyte interface properties degradation [51-53], (4) metal dissolution [54-56], (5) electrolyte decomposition [57-60], and (6) surface film formation [60,61],... 

Extensive biochemical and spectroscopic studies have been undertaken on hCP in order to investigate the nature of the copper centers and their role in structure-function relationships. However, the protein is very susceptible to aggregation, proteolysis, loss of copper, and other chemical degradations and requires careful preparation and handling in these circumstances it is difficult to review all the literature objectively and comprehensively. A three-dimensional crystal structure of hCP has been reported at a nominal resolution of 3.1A [7], but this resolution has been extended to just beyond 3.0 A. This chapter will summarize some of the more important biochemical and spectroscopic studies of the protein. It will then focus on the structural results recently obtained by X-ray crystallographic methods and attempt to explain putative functions of the protein in terms of its molecular structure. 

Stummeyer, K., Dickmanns, A., Muhlenhoff, M., Gerardy-Schahn, R., and Ficner, R. (2005). Crystal structure of the polysialic acid-degrading endosialidase of bacteriophage K1F. Nat. Struct. Mol. Biol. 12, 90-96. 

In mammals a single PPTase is used for the posttranslational modification of three different apo-proteins the carrier proteins of mitochondrial and cytosolic FASs and the aminoadipate semialdehyde reductase implicated in lysine degradation. The crystal structure of human PPT ase has been determined and found to be most closely related to the class II Sfp-like enzymes. Architectural and mechanistic differences between the type II human PPTase and the type I bacterial PPTases include a divalent cation coordinated by the a-phosphate of CoA, a Glu and an Asp residue, and three water ligands in type I PPTases versus a divalent cation coordinated by a- and /3-phosphates of CoA, two to three protein side chains, and a water molecule in the human PPT ase. 

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