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B.1.8 PARAM2 – Modification of PARAM1 for CO and Heme

PARAM2 has new parameters added pertaining to carbon monoxide binding to heme proteins.

B.1.8.1 Bonds
carbon monoxide stretch, see Caughey et al (Biochemical and Clinical Aspects of Hemoglobin Abnormalities).
Iron-carbon monoxide stretch, see Kroeker et al (J. Chem. Phys. 72: 4846, 1980) Values for the chemisorption of CO onto Fe matrix, data based on tunnelling spectroscopy; no data for proteins
Fe-proximal histidine N epsilon stretch, see K. Nagai et al (J. Mol. Biol. 136: 271, 1980); Kincaid et al (Proc. Nat. Acad. Sci. USA 76: 549, 1979) No change in equilibrium bond distance from that in Gelin's thesis.
B.1.8.2 Angles
Iron carbon monoxide bend, see Kroeker et al (vide supra)
Porphyrin nitrogen Fe carbon monoxide bend. No data available, values selected to be consistent with that for proximal histidine (5th ligand) nitrogen Fe porphyrin nitrogen bend.
B.1.8.3 Dihedrals
no data available, values selected to be consistent with that for X-FE-NR-X (i.e. just as the heme can rotate without great hindrance about the Iron-proximal histidine bond so can the CO rotate freely about the Iron-carbon bond)
B.1.8.4 Polarizabilities Etc.

The values for CM same as that for carbonyl carbon, and the values for OM same as that for carbonyl oxygen.