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Dynamic Motion and Rearranged Molecular Shape of Heme in Myoglobin: Structural and Functional Consequences
Department of Physical Chemistry, Graduate School of Pharmaceutical Sciences, Chiba University, Chuoh-Inohana, Chiba City, Chiba 260-8675, Japan
Received: 18 February 2013; in revised form: 7 March 2013 / Accepted: 7 March 2013 / Published: 11 March 2013
Abstract: Myoglobin, a simple oxygen binding protein, was reconstituted with various types of synthetic hemes to manipulate the heme-globin interactions. From the paramagnetic NMR analysis, small heme was found to rotate rapidly about the iron-histidine bond upon. This is a novel and typical example for the fluctuation of protein. The dynamic NMR analysis indicated that the 360° rotational rate of a small heme was 1,400 s−1 at room temperature. The X-ray analyses revealed that the tertiary structure of globin containing the smallest heme was closely similar to that of native protein despite extensive destruction of the specific heme-globin interactions. The functional analyses of O2 binding showed that the loose heme-globin contacts do not significantly affect the oxygen binding. On the other hand, the rearrangement of tetrapyrrole array and the non-planar deformation in porphyrin ring significantly affect the functional properties of myoglobin. These results, taken together, indicate that the essential factors to regulate the myoglobin function are hidden under the molecular shape of prosthetic group rather than in the nonbonded heme-globin contacts.
Keywords: host-guest chemistry; globin pocket; dynamic heme rotation; heme deformation; O2 binding
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MDPI and ACS Style
Neya, S. Dynamic Motion and Rearranged Molecular Shape of Heme in Myoglobin: Structural and Functional Consequences. Molecules 2013, 18, 3168-3182.
Neya S. Dynamic Motion and Rearranged Molecular Shape of Heme in Myoglobin: Structural and Functional Consequences. Molecules. 2013; 18(3):3168-3182.
Neya, Saburo. 2013. "Dynamic Motion and Rearranged Molecular Shape of Heme in Myoglobin: Structural and Functional Consequences." Molecules 18, no. 3: 3168-3182.