Src kinase is an enzyme of a family of tyrosine kinases proteins that is consisted of 451 amino acids and 4 domains. In biological processes, Src-family tyrosine kinases are important for cell signaling, proliferation, and survival. Their main function is to catalyze the phosphorlyation of a tyrosine residue in targeted proteins. The activity of Src-family tyrosine kinases is conducted by the intramolecular interactions involving SH2 and SH3 domains. Activated Src-family tyrosine kinases allow the SH2 and SH3 domains to participate in intermolecular interactions that target Src-family tyrosine kinases to their substrates. Hence, to understand mechanism of Src kinase, peptide inhibitors that bind to the active site and the SH2 domain of the Src kinase were synthesized. The modified peptide inhibitors with phosphotyrosine on one end and pentafluorophenylalanine on the other end are believed to be involved in the binding process. In the course of gaining better insights into the mechanism for regulation of Src kinase enzyme, the photophysical properties of phosphotyrosine and pentafluorophenylalanine peptides were studied.