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Examination of nickel(II) microperoxidase-11 (NiMP-11) was conducted via resonance Raman and ultraviolet-visible absorption spectra. The results showed that increase in heme distortion is caused by the peptide even after the removal of the rest of the protein and the Fe-histide linkage. Moreover, the results revealed that determination of the heme structure is attributed to the conformation of the fingerprint peptide, not merely to its presence, as shown by its H-dependent behavior.

Conformational differences in the hemes in ferricytochromes c(sub3) have been investigated using resonance Raman spectroscopy, molecular mechanics calculations and normal-coordinate structural decomposition techniques. The observed nonplanarity is mainly due to a fingerprint peptide segment, and factors influencing the folding pattern of the fingerprint peptide and other peptide-heme contacts also have an effect on heme conformation.

Resonance Raman spectroscopy was used to examine the axial ligation of nickel(II) 5,10,15,20-tetraphenylporphyrin with pyrrolidine or piperidine. The axial ligands and their orientations influenced the type and magnitude of the calculated nonplanar distortion. Narrow and symmetric Raman lines were observed because of the similarity in macrocyclic structural parameters of the conformers and the free rotation of the axial ligands. Analysis revealed the relationship between the orientations of axial ligands and the macrocyclic distortions.

A study was conducted to examine the effects of the symmetry of substitution pattern and substituent orientations on the out-plane and in-plane distortions of the macrocyle of nickel porphyrins. These nickel porphyrins were analyzed through the use of molecular mechanics calculations, X-ray crystallography, UV visible absorption spectroscopy and resonance Raman spectroscopy. Results revealed that out-plane and in-plane distortions were dependent on perturbation symmetry of the peripheral substituents.

Research was conducted to study the influence of central metals of various sizes on the macrocyclic structure of a series of 5,15-disubstituted metallophorphyrins. Methodologies used included X-ray crystallography, resonance Raman spectroscopy and molecular mechanics. The contributions of the ruf and dom deformations in the crystal structures of several metal complexes of the phorphyrins were found to be metal-dependent. Results indicate the quantitative validity of normal-coordinate structural decomposition.

A study was conducted to examine the effects of proteins on the nonplanarity of the macrocycle in nickel cytochrome c using molecular mechanics computations and resonance Raman spectroscopy. A dual-channel spectrometer was utilized to determine RR spectra while the POLYGRAF software was used to perform molecular mechanics computations. Results indicated that the nonplanar distortion of the porphyrin of cytochromes c is supported by a small protein segment.

The effect of substituents with increasing steric demands on the structure of nickel(II) 5,15-disubstituted porphyrins was studied by X-ray crystallography, UV-visible absorption spectroscopy, resonance Raman spectroscopy, molecular energy optimization computations and INDO/s molecular orbital computations. Findings showed that the distortion of the macrocyle for the disubstituted nickel porphyrins is a combination of ruffling and doming distortions. Also, the gal distortion can be precisely described in terms of displacements along the lowest-frequency normal coordinates of B1u and A2u symmetry.

The effects of ruffling on the axial ligation properties of a series of nickel(II) tetra(alkyl)porphyrins are investigated with UV-visible absorption spectroscopy, resonance Raman spectroscopy, X-ray crystallography, classical molecular mechanics calculations and normal-coordinate structural decomposition analysis. The study suggests that molecular mechanics calculations might aid in designing nano-devices with appropriate conformations and switching characteristics.

The effects of ruffling on the axial ligation properties of a series of nickel(II) tetra(alkyl)porphyrins have been investigated with UV-visible absorption spectroscopy, resonance Raman spectroscopy, X-ray crystallography, classical molecular mechanics calculations, and normal-coordinate structural decomposition analysis. For the modestly nonplanar porphyrins, porphyrin ruffling is found to cause a decrease in binding affinity for pyrrolidine and piperidine, mainly caused by a decrease in the binding constant for addition of the first axial ligand; ligand binding is completely inhibited for the more nonplanar porphyrins. The lowered affinity, resulting from the large energies required to expand the core and flatten the porphyrin to accommodate the large high-spin nickel(II) ion, has implications for nickel porphyrin-based molecular devices and the function of heme proteins and methyl-coenzyme M reductase. [ABSTRACT FROM AUTHOR]