Application to bacterial photosynthetic reaction centers

The difference spectra of the different charge separated states are dominated by the absorption changes of the chromophores and the quinones (Buchanan et al., 1992). Band shifts from 1743 cm to 1755 cm and from 1672 cm to 1712 cm are characteristic of the oxidation of bacteriochlorophyll b in an aprotic environment. They correspond to the absorbance changes of the 10-c-ester- and 9-keto-carbonyl groups of the primary 

The described studies of bacterial reaction centers indicate that FTIR it is a powerful analytical method, even useful for large proteins over 100 000 Dalton. 

Recent research focus now on applying FTIR methods to proteins without an intrinsic chromophore. In investigating oncogenic hras p21, for instance, protein activity is stimulated with a photolabile substance such as caged GTP (Fig 6.6-21). A UV laser flash, which separates the head group and releases GTP, triggers the GTPase activity of p21 This new experimental approach offers now a very broad applicability to study chemical reactions by time-resolved FTIR. 

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