Experimental Kinetic Approaches to Analyse PCET Reactions

2 Experimental Kinetic Approaches to Analyse PCET Reactions 

In this review, the phrase PCET is used to comprise kinetically gated and coupled stepwise mechanisms as well as concerted PCET reactions. The reasons for this broad definition are rooted in the experimental challenge of 

To tackle the above discussed challenge in detecting potential PCET intermediates, an intricate experimental approach has been developed to measure the rate constant of the PT step independently from the ET (see e.g. ref. 188 193). When performing experiments in unbuffered solutions, pH indicators, such as phenol red, can be used as reporters of the PT step. The rate constants obtained from the colour change of the dye correspond to the PT of interest, assuming that the equilibration between the protons in the active site and the bulk solvent is not rate-limiting. 

The mechanism of hydride transfer reactions is of special biochemical interest due to the enzymatic significance of the cofactor NAD(P)H (see 3.2). In case of a stepwise PCET reaction, short-lived radical intermediates are expec-ted44 46 existence of unpaired electrons may be probed by analysing the 

In cytochrome c nitrite reductase, a PCET mechanism was established using a combination of catalytic and non-catalytic PFV. °  

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