Protein structure patterns hemoglobin

In 1954, Perutz introduced the isomorphous replacement method for determining phases. In this procedure a heavy metal, such as mercury or platinum, is introduced at one or more locations in the protein molecule. A favorite procedure is to use mercury derivatives that combine with SH groups. The resulting heavy metal-containing crystals must be isomorphous with the native, i.e., the molecules must be packed the same and the dimensions of the crystal lattice must be the same. However, the presence of the heavy metal alters the intensities of the spots in the diffraction pattern and from these changes in intensity the phases can be determined. Besides the solution to the phase problem, another development that was absolutely essential was the construction of large and fast computers. It would have been impossible for Perutz to determine the structure of hemoglobin in 1937, even if he had already known how to use heavy metals to determine phases. 

Connolly developed a computational technique for docking two protein structures based on matching complementary patterns of knobs and holes (106). The algorithm was used to predict the association of the a and fi subunits of hemoglobin to form the corrext a-/ dimer. 

In a schematic elution pattern of some standard proteins, peroxidase was eluted first with saline, BSA came next with glycine buffer at pH 6.6 and hemoglobin and catalase were eluted at a pH of nearly 8.0. Aldolase, lysozyme, chymotrypsinogen A, malate dehydrogenase, and cytochrome c were not eluted under these conditions, but were eluted with 0.1% SDS. The adsorption order does not depend on the isoelectric point, the molecular mass, or the content of basic amino acids. However, adsorption may depend on the o -helix content, and the secondary structure of those proteins may be important. We have also reported on protein adsorption and separation on siliconized glass surfaces (30), and on the adsorption and separation of nucleic acids on those same surfaces (31-35). 

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