Hydrostatic pressure effects on the fluorescence of tyrosine solution with different concentrations of copper ion

The effects of hydrostatic pressure on the fluorescence of tyrosine (Tyr) solution with different concentrations of copper ion (Cu²⁺) were investigated. The fluorescent intensity of pure Tyr aqueous solution enhanced with the increase of hydrostatic pressure, the fluorescent intensity increased by 8.8% when the pressure was up to 60 MPa. The fluorescence of Tyr aqueous solution was quenched obviously due to complex formation with Cu²⁺ and the quenching became stronger when the concentration of Cu²⁺ was higher. When the concentration ratio of Cu²⁺ and Tyr ([Cu²⁺]/[Tyr]) increased from 0 to 40, the fluorescent intensity decreased to 19.0% at 0.1 MPa and 24.2% at 60 MPa. It was also found that the effects of pressure on the fluorescent intensity of Tyr aqueous solution were different at various [Cu²⁺]/[Tyr]. The fluorescent intensity increased by 14.4% and 38.4% for 1 and 40 ratio respectively when the pressure was changed from 0.1 MPa to 60 MPa.