Absorption shifts of diastereotopically ligated chlorophyll dimers of photosystem I.

The light-harvesting chlorophyll (Chl) molecules of photosynthetic systems form the basis for light-driven energy conversion. In biological environments, the Chl chromophores occur in two distinct diastereotopic configurations, where the α and β configurations have a magnesium-ligating histidine residue and a 17-propionic acid moiety on the opposite side or on the same side of the Chl ring, respectively. Although β-ligated Chl dimers occupy conserved positions around the reaction center of photosystem I (PSI), the functional relevance of the α/β configuration of the ligation is poorly understood.

Many faces of entropy or Bayesian statistical mechanics.

Some 80-90 years ago, George A. Linhart, unlike A. Einstein, P.

Analysis of electron-transfer rate constant in condensed media with inclusion of inelastic tunneling and nuclear quantum effects.

We have developed a theoretical formulation for evaluating the nonadiabatic electron-transfer (ET) rate constant in condensed medium which takes into account both inelastic electron tunneling and nuclear quantum effects. The derived formula allows us to calculate the ET rate as a function of the free-energy gap between the ET donor and acceptor states using the information on the spectral density associated with environmental polarization fluctuation and the temporal correlation function of electronic tunneling matrix element. Model calculations have been performed illustratively.

DNA duplex length and salt concentration dependence of enthalpy-entropy compensation parameters for DNA melting.

Systematical differential calorimetry experiments on DNA oligomers with different lengths and placed in water solutions with various added salt concentrations may, in principle, unravel important information about the structure and dynamics of the DNA and their water-counterion surrounding. With this in mind, to reinterpret the most recent results of calorimetric experiments on DNA oligomers of such a kind, the recent enthalpy-entropy compensation theory has been used. It is demonstrated that the application of the latter could enable direct estimation of thermodynamic parameters of the microphase transitions connected to the changes in DNA dynamical regimes versus the length of the biopolymers and the ionic strengths of their water solutions, and this calls for much more systematical experimental and theoretical studies in this field.

Conformation dependence of DNA exciton parentage.

Singlet electronic excitations of DNA duplex trimers and tetramers with regular homogeneous base-pair sequences ((dA)n.(dT)n and (dG)n.(dC)n, with n=3, 4) have been investigated in vacuo using semiempirical quantum chemistry in a Zerner's Intermediate Neglect of Differential Overlap (ZINDO) approximation.