Comparative Study of Spectral and Functional Properties of Wild Type and Double Mutant H(L173)L/I(L177)H Reaction Centers of the Purple Bacterium .

Previously, we found that in the reaction center (RC) of the purple bacterium , formation of heterodimeric primary electron donor (P) caused by the substitution of His-L173 by Leu, was compensated by the second mutation Ile-L177 - His. Significant changes in the spectral properties, pigment composition, and redox potential of P observed in the H(L173)L RC, are restored to the corresponding characteristics of the native RC in the RC H(L173)L/I(L177)H, with the difference that the energy of the long-wavelength Q optical transition of P increases significantly (by ~75 meV). In this work, it was shown using light-induced difference FTIR spectroscopy that the homodimeric structure of P is preserved in the RC with double mutation with partially altered electronic properties: electronic coupling in the radical-cation of the P dimer is weakened and localization of the positive charge on one of its halves is increased.

Anomalous Temperature Dependence of the Triplet-Triplet Energy Transfer in I(L177)H Mutant Reaction Centers.

In photosynthetic reaction centers, quenching of the primary donor triplet state by energy transfer to the carotenoid molecule provides efficient suppression of generation of singlet-excited oxygen, potent chemical oxidant. This process in the reaction centers is thermoactivated, and discontinues at temperatures below 40 K. In these reaction centers, substitution of amino acid residue isoleucine at the 177 position of the L-subunit with histidine results in the sharp decrease of activation energy, so that the carotenoid triplets are populated even at 10 K.

Evaluation of Five Screening Tools in Detecting Physical Frailty in Cirrhosis and Their Prognostic Role.

: Physical frailty (PF) is a syndrome of decreased physical function and reserves, preventing patients from coping with stressful events. PF screening tools in patients with liver cirrhosis (LC) can help evaluate the risk of complications and death. The aim of this study was to assess the performance of five screening tools in detecting PF and their ability to predict 18-month mortality in LC.

Evaluation of parameters influencing the quality of colon preparation with a split-dose regimen of sulfate salts.

Background: Bowel cleansing is an important factor for the quality of colonoscopy. We aimed to evaluate the efficacy of split-dose oral sulfate salts on bowel preparation and to determine parameters influencing the quality of bowel cleaning.

Method: Consecutive adults who completed their preparation for colonoscopy with a regimen of sulfate salts were enrolled.