The Structure of the "Short Axis" Form of the Complex of the Fab HyHEL-5 and Lysozyme. Gerson H Cohen, National Institutes of Health, NIDDK/LMB, Bethesda, MD 20892-0560 USA.
Crystals of the complex between lysozyme and the Fab HyHEL-5 have been grown in two forms, both monoclinic P21, with the distinguishing feature being the length of the unique axis. The long axis form, whose structure has been published, has a cell of a = 54.79, b = 74.82, c = 78.92 Å, ß = 101.82deg. and the short axis form, which was only obtained once: a = 54.9, b = 65.2, c = 78.6Å, ß = 102.4deg.. Due to an mishap during data collection on the short axis form, the complete set of data was not collected; the highest resolution data are only 3 Å and in the range 4-3 Å less than 50% of the theoretical data are available. This proved sufficient to define the orientation of the domains of the complex structure and to trace most of the main chains but insufficient to establish the location of a significant number of the side chains. We have recently achieved a more complete solution of the problem using the torsion dynamics procedure in the prerelease version 3.851 of XPLOR (Online). We will show a model for the short axis form of the complex and compare it with the long axis form. Unfortunately, the poor resolution of the short axis data precludes a comparison of the water structure in the antibody_lysozyme interface.
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