Structural Effects of Binding of Merbromine to Horse Hemoglobin a Crystallographic Approach. A. N. Rashid, S. Hilgenkamp, M. Astatke, L. Parkhurst, J.J. Stezowski, 731 HaH Univ. of Nebraska, Lincoln, Nebraska 68588-0304

Crystallographic studies of chemically modified horse hemoglobin have been undertaken to assist in the development of photoafinity labeling methods, which are used to obtain the approximate distances from portions of the protein to the point of attachment of the probe. We are currently solving the crystal structure to 2.4 Å resolution. These crystals were isomorphous with the unmodified horse hemoglobin crystals. The current R factor is 23%. The crystals belong to the space group C2 with cell dimensions of a=108.240 b=63.130 c=54.50 (=90.0 (=100.85 (=90.0.