1H-NMR heme resonance assignments by selective deuterations in low-spin complexes of ferric hemoglobin A |
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Affiliation: | 1. Department of Chemistry, University of California, Davis, CA U.S.A.;2. MRC Laboratory of Molecular Biology, Hills Road, Cambridge U.K.;1. Department of Biology, University of Kentucky, Lexington, KY 40502, USA;2. Structural Biology Initiative, CUNY Advanced Science Research Center, New York, NY 10031, USA;3. Ph.D. Program in Biochemistry, Graduate Center, City University of New York, NY 10016, USA;4. Department of Chemistry and Biochemistry, City College of New York, NY 10031, USA;5. Ph.D. Programs in Biochemistry, Chemistry and Biology Ph.D. Programs, Graduate Center, City University of New York, NY 10016, USA;1. Department of Applied Physics, Ghent University, Sint-Pietersnieuwstraat 41 B4, 9000 Gent, Belgium;2. Separation Science Group, Department of Organic Chemistry, Ghent University, Krijgslaan 281 S4-bis, 9000 Gent, Belgium;3. Research Group Molecular Odor Chemistry, Department of Microbial and Molecular Systems (M2S), KU Leuven, Technology Campus, Gebroeders De Smetstraat 1, 9000 Gent, Belgium;4. Department of Industrial Biological Sciences, Ghent University, Graaf Karel de Goedelaan 5, 8500 Kortrijk, Belgium;1. Jiangxi Provincial Key Laboratory of Functional Molecular Materials Chemistry, Jiangxi University of Science and Technology, Ganzhou 341000, China;2. College of Chemistry and Chemical Engineering, Jiangxi Normal University, Nanchang 330022, China |
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Abstract: | The heme methyl and vinyl α-proton signals have been assigned in low-spin ferric cyanide and azide ligated derivatives of the intact tetramer of hemoglobin A, as well as the isolated chains, by reconstituting the proteins with selectively deuterated hemins. For the hemoglobin cyanide tetramer, assignment to individual subunits was effected by forming hybrid hemoglobins possessing isotope-labeled hemins in only one type of subunit. The heme methyl contact shift pattern has 1-methyl and 5-methyl shifts furthest downfield in both chains and the individual subunits of the intact hemoglobin in both the cyanide- and azide-ligated species, which is consistent with a dominant rhombic perturbation due to the proximal His-F8 imidazole π bonding in the known structure for human adult hemoglobin. The individual chain and subunit assignments confirm that the detailed electronic/magnetic properties of the heme pocket are essentially unaltered upon assembling the R-state tetramer from the isolated subunits. |
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