Temperature-Dependent Volume Change of the Initial Step of the Photoreaction of Photoactive Yellow Protein (PYP) Studied by Transient Grating

Abstract

The energetics and protein dynamics of photoactive yellow protein (PYP) were studied by transient grating (TG) and photoacoustic (PA) spectroscopies. The enthalpy difference (ΔH) between the ground state (pG) and the first intermediate (pR) at 20 °C was determined by the TG method as 160 kJ/mol, which is much larger than ΔH of the photoisomerized chromophore (p-coumaric acid) in water (50 kJ/mol). By simultaneous measurements of the TG and PA signals, the volume change (ΔV) for the pG → pR process is determined to be −7 cm3/mol (contraction) at 20 °C. Interestingly, the volume contraction increases with decreasing temperature. At 0 °C the volume change becomes ca. −15 cm3/mol. This temperature-dependent volume change may indicate the structural fluctuation of PYP protein in the solution phase.

An optical high-pressure cell for transient grating measurements of biological substance with a high reproducibility

“…11,13,17,23,24 A XeCl excimer laser-pumped dye laser ͑Lambda Physik Compex 102xc, Lumonics Hyper dye 300; = 465 nm͒ was split into two by a beam splitter and crossed on the quartz sample cell. 11,13,17,23,24 A XeCl excimer laser-pumped dye laser ͑Lambda Physik Compex 102xc, Lumonics Hyper dye 300; = 465 nm͒ was split into two by a beam splitter and crossed on the quartz sample cell.…”

“…The body of the cell ͑1 in Fig. [9][10][11][12][13][14][15][16][17][18][19] The internal temperature of the chamber is controlled by circulating temperature-controlled water into a thermostatic hole ͑2͒ drilled through the cell, and it is monitored with an antipressure thermocouple ͑K type͒ ͑15͒ plugged into the body. The cell is in a cubic shape and has two window ports in opposite positions of the sides.…”

“…[9][10][11][12][13][14][15][16][17][18][19] For that purpose, the target sample should be replaced by the calorimetric reference sample under the same conditions to compare the signal intensity. The most serious problem was a quantitative comparison of the TG signals of different samples under high pressure because we have to compare the signal intensity of the sample with that of a calorimetric reference sample under the same experimental condition to eliminate all factors that depend on the experimental conditions.…”

Photoactive Yellow Protein, the Xanthopsin

“…The (free) energy content of PYP increases 120-160 kJ mol -1 upon formation of pR (van Brederode et al 1995;Takeshita et al 2000). Half of the energy of an absorbed photon is thus stored in the holo-protein at this point (a photon with a wavelength of 446 nm has an energy content of 268 kJ mol -1 ).…”

Ligand Dissociation Process from Myoglobin Monitored by the Time‐Resolved Volume Change

“…9 We have been successful recently in revealing several spectral silent processes of protein reactions by monitoring the volume changes. [10][11][12][13][14][15][16][17][18][19] Even a protein-protein interaction can be monitored in timedomain by this method. 20 Here, I will review our studies of the ligand dissociation process of carboxymyoglobin (MbCO) by time-resolved volume detection.…”