Relation between the structure and function of proteins studied by the changes of tyrosine and tryptophan residues.

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To get insight into how the quaternary structure changes correlate to their functions, we examined the near-UV CD and UV resonance Raman spectra of hemoglobin and the domein of Src-homology-3 protein with and without ligands. Using four newly synthesized mutant hemoglobins at α42Tyr,α140Tyr,β145Tyr, and/or β37Trp, it was clarified that the main contributors for a negative CD band, a T-sate marker band, are α140Tyr and β145Tyr, located at C-terminal positions. The T-structure specific UV resonance Raman bands of Tyr and Trp were characterized using a natural mutant Hb, Hb M Boston and a Ni-Fe Hybrid hemoglobin.Src-homology-3(SH3) protein recognize a Pro rich peptides and communicate with the other proteins. We demonstrated that SH3 interacts to the ligand peptide via Tyr residue(s) using UV CD and UV resonance Raman spectoscopy. SH3 has six Tyr residues. Specific Tyr residue for the interaction with Pro-rich peptide was specified as 14Tyr using mutants synthesized in E.coli each Tyr replaced by Ala. Interestingly, Src-SH3 and PI3K-SH3 showed different shtructure changes with the interaction of ligand peptides reflecting the different protein recognition.