The role of Tyr61 in synechocystis hemoglobin in regulating E-helix movement

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Venugopal, Anand
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Mark Hargrove
Michael Shogren-Knaak
Hans Stauffer
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Biochemistry, Biophysics and Molecular Biology

The Department of Biochemistry, Biophysics, and Molecular Biology was founded to give students an understanding of life principles through the understanding of chemical and physical principles. Among these principles are frontiers of biotechnology such as metabolic networking, the structure of hormones and proteins, genomics, and the like.

The Department of Biochemistry and Biophysics was founded in 1959, and was administered by the College of Sciences and Humanities (later, College of Liberal Arts & Sciences). In 1979 it became co-administered by the Department of Agriculture (later, College of Agriculture and Life Sciences). In 1998 its name changed to the Department of Biochemistry, Biophysics, and Molecular Biology.

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  • Department of Biochemistry and Biophysics (1959–1998)

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Hexacoordinate hemoglobins have been discovered that have yet to have a functional role confidently assigned to them. The eubacteria synechocystis sp. PCC 6803 has been found to have a truncated hemoglobin which is hexacoordinated. The structures of the hexacoordinated and cyanide bound forms of synechocystis hemoglobin have been solved, and a large shift in the E-helix has been seen upon ligand binding. Also, the loop connecting the E and F helix contains residues Tyr61 and Asp62 that are involved in hydrogen bonding networks in the cyanide-bound and hexacoordinate states respectively. A mutation was made to the Y61 residue to make it leucine, and this mutant protein was studied to investigate its role in regulating intramolecular histidine coordination to the heme iron. CO binding studies of flash photolysis and rapid mixing were performed to extract values for the CO binding rate and the rate of hexacoordination. The Y61L mutant protein has a rate of hexacoordination that is nearly 2.5 times greater than that of wild type synechocystis hemoglobin. Also, NMR spectra were taken on the wild type protein and it was revealed that a secondary conformation of the protein than that reported is present. Upon further inspection, it was suspected that the secondary conformation was most likely due to a covalent linkage to the heme from the H117 residue.

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Mon Jan 01 00:00:00 UTC 2007