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Research was conducted to determine the structural and catalytic characteristics of W161F human manganese superoxide dismutase (MnSOD), the mutant with the replacement tryptophan (Trp) 161 -> Phe. It was observed that Trp 161 in human MnSOD is not required for catalysis in the reduction half-cycle superoxide decay. Its substitution with Phe led to modest decreases in the steady-state constant for the catalysis. This indicates that a significant role of Trp 161 in the active site is to promote the dissociation of product peroxide.

The tyrosine residue at position 34 of the human manganese superoxide dismutase was replaced with phenylalanine to determine the function of this conserved residue in the metalloenzyme. The mutated enzyme has comparable structure with the native form based on crystallographic studies, is less thermolabile and allows the investigation of the function of the conserved residue in catalysis. There is a 10-fold reduction in activity levels of the mutant enzyme indicating that the tyrosine residue may have a function in the proton-transfer pathway.

Site-directed mutagenesis was used to create a mutant of the human manganese superoxide dismutase where the nonliganding glutamine residue at position 143 was replaced with asparagine. There is a difference in the crystal structures of the native and the mutant enzymes owing to the insertion of a water molecule in the active site. The mutant enzyme is more stable than the wild-type but its catalytic activity is two to three fold lower. The glutamine residue appears to promote a favorable reduction potential.

Crystal structure of the wild-type Gene V Protein (GVP) from Ff filamentous phage suggests that the amino acid residues Y41H and Y41F, at site 41 of the protein, are vital to the dimer-dimer interactions of the protein-ssDNA complex. The dimer-dimer contacts in the wt-GVP crystal influence GVP grouping in the absence of DNA. The presence of DNA results in cooperative formation of the GVP-ssDNA complex.