Miniaturized heme proteins: crystal structure of Co(III)-mimochrome IV(730 views) Di Costanzo L, Geremia S, Randaccio L, Nastri F, Maglio O, Lombardi A, Pavone V
Keywords: Miniaturized Hemeproteins, Model Compounds, Protein Design, Structure X-Ray Diffraction, Cobalt, Hemoglobin, Hemoprotein, Metalloprotein, Peptide, Article, Chemical Structure, Circular Dichroism, Comparative Study, Crystal Structure, Nuclear Magnetic Resonance, Priority Journal, Solid State, X Ray Diffraction, Arginine, Cations, Crystallography, Deuteroporphyrins, Glutamic Acid, Isomerism, Miniaturization, Biomolecular, Peptide Fragments, Protein Conformation, Protein Folding, Protein Structure, Secondary,
Affiliations: *** IBB - CNR ***
Department of Chemistry, University of Naples Federico II, Complesso Universitario MSA, Via Cynthia 45, 80126 Napoli, Italy
Ctr. Excellence Biocrystallography, Department of Chemical Science, University of Trieste, Via L. Giorgieri 1, 34127 Trieste, Italy
Ist. di Biostrutture e Bioimmagini, CNR, via Mezzocannone 6, 80134 Napoli, Italy
References: Not available.
Miniaturized heme proteins: crystal structure of Co(III)-mimochrome IV
Protein design provides an attractive approach to test the essential features required for folding and function. Previously, we described the design and structural characterization in solution of mimochromes, a series of miniaturized metalloproteins, patterned after the F-helix of the hemoglobin beta-chain. Mimochromes consist of two medium-sized helical peptides, covalently linked to the deuteroporphyrin. CD and NMR characterization of the prototype, mimochrome I, revealed that the overall structure conforms well to the design. However, formation of D and L diastereomers was observed. To overcome the problem of diastereomer formation, we re-designed mimochrome I, by engineering intramolecular, interchain interactions. The resulting model was mimochrome IV: the solution structural characterization showed the presence of the L isomer as a unique form. To examine the extent to which the stereochemical stability and uniqueness of mimochrome IV was retained in the solid state, the crystal structure of Co(III)-mimochrome IV was solved by X-ray diffraction, and compared to the solution structure of the same derivative. Co( III)-mimochrome IV structures, both in solution and in the solid state, are characterized by the following common features: a bis-His axial coordination, a Lambda configuration around the metal ion, and a predominant helical conformation of the peptide chains. However, in the crystal structure, intrachain Glu1-Arg9 ion pairs are preferred over the designed, and experimentally found in solution, interchain interactions. This ion pairing switch may be related to strong packing interactions.
Miniaturized heme proteins: crystal structure of Co(III)-mimochrome IV