Figure 3

Light-induced P840⁺/P840 FTIR difference spectra of the wild-type (green line), the L688C (red line) and the V689C (blue line) RCs at 220 K.

(A) Whole region (3000–970 cm⁻¹); (B) S-H stretching region (2580–2525 cm⁻¹); (C) C=O stretching region (1760–1620 cm⁻¹). The spectra in the 2400–2300 cm⁻¹ regions are not shown because of the large contribution of CO₂ bands.