Theoretical Study of Trapping Sites for Muon in the Heme Group of Cytochrome c

D. Cammarere (SUNY Albany, Albany NY; Tamarac High School, Brittenkill NY), R. H. Scheicher (SUNY Albany), T. M. Briere (KEK-MSL, Tsukuba, Japan), N. Sahoo (Albany Medical College, Albany NY; SUNY Albany), T. P. Das (SUNY Albany), F. L. Pratt (RIKEN-RAL, Didcot, UK; Clarendon Laboratory, Oxford, UK), K. Nagamine (KEK-MSL; RIKEN, Wako-shi, Japan)

We have carried out an extensive analysis for the trapping sites for muon in the heme plane of Cytochrome c using the
Unrestricted Hartree-Fock Cluster Procedure. From our analysis it appears that the likely trapping sites are the four nitrogens
and their two adjacent carbons on the four pyrrole rings. The presence of the imidazole and methionine ligands destroys the
tetragonal symmetry and as a result of that the strengths of trapping are not the same for different pyrrole rings. The strongest
trapping is still at the pyrrole nitrogen found before, the Nm bond being directed to the vicinity of the nitrogen, Ne,
of the imidazole. The predicted Knight-shifts using available magnetic susceptibility data(A. Tasaki et al., Biochim. Biophys.
Acta 140), 284 (1967) at (150 K, 293.15 K) are (172.7 and 88.4) ppm, experimented tests of which are awaited.

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