Density Functional and MP2 Calculations of Spin Densities of Oxidized 3-Methyl Indole. Models for Tryptophan Radicals.
Final rept. Jan 95-Jan 96,
ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
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Ab initio calculations have been carried out on 3-methyl indole, and the cation and neutral radicals of 3-methyl indole, using Density Functional Theory DFT, the Becke3-Lee-Yang-Parr functional, and the 6-31G, 6-31G, 3-21G, and TZ2P basis sets. Optimized geometries, vibrational frequencies and, for the radicals, atomic spin densities are calculated. The latter are compared to experimental spin densities recently determined for the tryptophan-191 radical of compound ES of the enzyme cytochrome-c-peroxidase. The DFT spin densities for the cation radical of 3-methyl indole are in excellent agreement with the data for the tryptophan-l91 radical, which supports the conclusion that the tryptophan radical is a cation radical. The results are compared to calculations using second-order Moller-Plesset theory MP2 and the 6-31G basis set. The MP2 spin densities are in significantly worse agreement with the experiment spin densities. jg p3
- Organic Chemistry
- Physical Chemistry
- Quantum Theory and Relativity