The theory of chemically induced dynamic electron polarization for radical pair recombination in low dimensional space

1D Radical Motion in Protein Pocket: Proton-Coupled Electron Transfer in Human Serum Albumin

Photoinduced, proton-coupled electron transfer (ET) between 9,10-anthraquinone-2,6-disulfonate (ADQS) and an amino acid residue of tryptophan in human serum albumin (HSA) was observed using time-resolved electron paramagnetic resonance (TREPR). The ET reaction reduces the protein binding affinity of the ligand. TREPR chemically induced dynamic electron polarization (CIDEP) spectra establish that photoinduced ET takes place from the tryptophan residue (W214) to the excited triplet state of AQDS2- while bound in subdomain IIA, a protein cleft of HSA. The TREPR CIDEP signals also reveal that the anion radical of the ligand escapes toward the bulk water region by a one-dimensional translation diffusion process within the protein's pocket area. This pilot study of HSA demonstrates how TREPR CIDEP can provide significant means to investigate dynamic characteristics of protein-surface reactions.

Non-Markovian stochastic Liouville equation and its Markovian representation

The non-Markovian variant of the stochastic Liouville equation (SLE) is studied within the continuous time random walk approach (CTRWA). The CTRWA-based non-Markovian SLE is shown to be equivalently represented by the corresponding conventional Markovian SLE. This Markovian representation provides a rigorous method for deriving the non-Markovian SLE and allows for a physically clear interpretation of the specific features of this SLE. It also enables one to develop convenient non-Markovian models useful for applications, some of which are discussed in detail. Special attention is given to the discussion of anomalous long-tailed CTRW processes and non-Markovian SLE. The obtained results are applied to the analysis of the effect of rate fluctuations on chemical reaction kinetics. It is shown, in particular, that the anomalous fluctuations not only influence the reaction rate but also change the reaction kinetics itself.