Exploring the interdependence of calcium and chloride activation of O evolution in photosystem II.

Calcium and chloride are activators of oxygen evolution in photosystem II (PSII), the light-absorbing water oxidase of higher plants, algae, and cyanobacteria. Calcium is an essential part of the catalytic MnCaO cluster that carries out water oxidation and chloride has two nearby binding sites, one of which is associated with a major water channel. The co-activation of oxygen evolution by the two ions is examined in higher plant PSII lacking the extrinsic PsbP and PsbQ subunits using a bisubstrate enzyme kinetics approach.

A targeted metabolomic protocol for short-chain fatty acids and branched-chain amino acids.

Research in obesity and metabolic disorders that involve intestinal microbiota demands reliable methods for the precise measurement of the short-chain fatty acids (SCFAs) and branched-chain amino acids (BCAAs) concentration. Here, we report a rapid method of simultaneously determining SCFAs and BCAAs in biological samples using propyl chloroformate (PCF) derivatization followed by gas chromatography mass spectrometry (GC-MS) analysis. A one-step derivatization using 100 µL of PCF in a reaction system of water, propanol, and pyridine (v/v/v = 8:3:2) at pH 8 provided the optimal derivatization efficiency.

Chia seed supplementation and disease risk factors in overweight women: a metabolomics investigation.

Objective/setting: This study assessed the effectiveness of milled and whole chia seed in altering disease risk factors in overweight, postmenopausal women using a metabolomics approach.

Design/intervention: Subjects were randomized to chia seed (whole or milled) and placebo (poppy seed) groups, and under double-blinded procedures ingested 25 g chia seed or placebo supplements each day for 10 weeks.

Subjects: Subjects included 62 overweight (body-mass index 25 kg/m(2) and higher), nondiseased, nonsmoking, postmenopausal women, ages 49-75 years, with analysis based on the 56 subjects who completed all phases of the study.

An alternative method for calcium depletion of the oxygen evolving complex of photosystem II as revealed by the dark-stable multiline EPR signal.

The dark-stable multiline EPR signal of photosystem II (PSII) is associated with a slow-decaying S(2) state that is due to Ca(2+) loss from the oxygen evolving complex. Formation of the signal was observed in intact PSII in the presence of 100-250 mM NaCl at pH 5.5.