The document describes research on crystallizing and determining the crystal structures of phenylalanine mutants of the electron transfer protein azurin. Key findings include: 1) Crystals of wild-type azurin and double/triple phenylalanine mutants were grown and their structures were solved. 2) Comparisons revealed differences in backbone structure, water content near the copper active site, and carbonyl ligand bonding angles between mutants. 3) Mutating residues further from the active site to phenylalanine had greater effects on the protein's redox potential, suggesting they influence electron transfer through structural changes.