16 research outputs found
Batch-Type Chemiluminescence Detection Cell for Sensitization and Simplification of Capillary Electrophoresis
Direct Detection of Biomolecules in a Capillary Electrophoresis−Chemiluminescence Detection System
Effect of Saliva on Measurement of Chemiluminescence by a Micro-Reactor Incorporating a Micro-Channel
Synthesis and Fluorescence Properties of 2,6-Diaryl-4-(2-substituted thienyl-5-yl)pyridines
Effect of Saliva on Measurement of Chemiluminescence by a Micro-Reactor Incorporating a Micro-Channel
Effect of saliva on measurement of chemiluminescence was examined by a micro-reactor incorporating a micro-channel. Sodium hypochlorite and hydrogen peroxide solutions were delivered into a micro-channel developed in a micro-reactor by a syringe pump, providing a laminar flow liquid-liquid interface in the channel and leading to chemiluminescence from singlet oxygen. It was found under certain conditions including saliva that ca. 5% chemiluminescence of the total chemiluminescence was lost in the micro-channel through the reaction of saliva with singlet oxygen or hydrogen peroxide
Positive/Negative Allosteric Modulation Switching in an Umami Taste Receptor (T1R1/T1R3) by a Natural Flavor Compound, Methional
Taste is a vital sensation for vertebrates, enabling the detection of nutritionally important substances or potential toxins. A heteromeric complex of two class C GPCRs, T1R1 and T1R3, was identified as the umami (savory) taste receptor. Amino acids and 5′-ribonucleotides are well known to be natural ligands for human T1R1/T1R3. In this study, we reveal that methional, which is a familiar flavor component in foods, is an allosteric modulator of T1R1/T1R3. Receptor expression experiments showed that methional served as a positive allosteric modulator (PAM) of human T1R1/T1R3 and functioned as a negative allosteric modulator (NAM) of mouse T1R1/T1R3. Although amino acids and 5′-ribonucleotides bound to the extracellular domain of T1R1, the use of interspecies chimeric receptors demonstrated that methional interacted with the transmembrane domain of T1R1. Site-directed mutagenesis and molecular modeling showed that methional could potentially bind at two distinct sites in the transmembrane domain of T1R1 and that the amino acid residues in the bottom of the allosteric pocket engendered the switch between the PAM and NAM modes, which could contribute to switching the binding position of methional. These results may be applicable for elucidating the molecular mechanisms underlying ligand recognition by other class C GPCRs