Neutron Diffraction Study of Carbonmonoxymyoglobin

Cheng, X., Schoenborn, B. P. (July 1991) Neutron Diffraction Study of Carbonmonoxymyoglobin. Journal of Molecular Biology, 220 (2). pp. 381-400. ISSN 0022-2836 (Print)0022-2836 (Linking)

DOI: 10.1016/0022-2836(91)90020-7


Neutron diffraction data from a crystal of carbonmonoxymyoglobin were refined by PROLSQ, a modern restrained least-squares procedure in reciprocal space, in conjunction with a solvent analysis technique, to a final R-factor of 11.3%. The ligand CO occupies two sites and its binding conformations are distorted from the linear conformation. The N.epsilon. atom of the distal histidine residue is deprotonated (not deuterated), and a water molecule is bound to the atom of the distal histidine. The side-chain of Lys56 (D6) exists in two alternative charge-binding sites. His24 (B5) and His119 (GH1) share a hydrogen atom. His12 (A10) and His36 (C1) are deprotonated. The deprotonated imidazole ring of His12 (A10) may act as a hydrogen-bond acceptor. The heme group is planar within 0.09 .ANG. root-mean-square (r.m.s.) deviation from planarity. The solvent environments for the two propionic acid groups are different. The side-chain of Arg45 (CD3) forms hydrogen bonds with the side chain of Asp60 (E3) and one of the two propionic acid groups. An average N-2H...O angle in helical regions is 147(.+-. 11).degree.. Eleven main-chain amide hydrogen atoms from hydrophobic residues do not exchange with deuterium. The overall atomic occupancy factors for the main-chain and side-chain atoms are quite uniform, at 0.97 (.+-. 0.07) and 0.93(.+-. 0.10), respectively, as shown by an occupancy analysis made at the end of the refinement procedure.

Item Type: Paper
Uncontrolled Keywords: Amino Acid Sequence Binding Sites Carbon Monoxide/metabolism Crystallization Fourier Analysis Heme/metabolism Mathematics Models, Molecular Molecular Sequence Data Myoglobin/*chemistry/metabolism Neutrons Protein Conformation Scattering, Radiation
Subjects: organs, tissues, organelles, cell types and functions > organs types and functions > metabolism
CSHL Authors:
Communities: CSHL labs
Depositing User: Matt Covey
Date: 20 July 1991
Date Deposited: 22 Dec 2015 17:15
Last Modified: 22 Dec 2015 17:15
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