Tethering Agent Research Articles

Tethering Chemistry and K+ Channels

Voltage-gated K+ channels are dynamic macromolecular machines that open and close in response to changes in membrane potential. These multisubunit membrane-embedded proteins are responsible for governing neuronal excitability, maintaining cardiac rhythmicity, and regulating epithelial electrolyte homeostasis. High resolution crystal structures have provided snapshots of K+ channels caught in different states with incriminating molecular detail. Nonetheless, the connection between these static images and the specific trajectories of K+ channel movements is still being resolved by biochemical experimentation. Electrophysiological recordings in the presence of chemical modifying reagents have been a staple in ion channel structure/function studies during both the pre- and post-crystal structure eras. Small molecule tethering agents (chemoselective electrophiles linked to ligands) have proven to be particularly useful tools for defining the architecture and motions of K+ channels. This Minireview examines the synthesis and utilization of chemical tethering agents to probe and manipulate the assembly, structure, function, and molecular movements of voltage-gated K+ channel protein complexes.

Heterogenized HRh(CO)(PPh 3) 3 on zeolite Y using phosphotungstic acid as tethering agent: a novel hydroformylation catalyst

Heterogenization of HRh(CO)(PPh 3) 3 tethered through phosphotungstic acid to zeolite Y support, gives a novel hydroformylation catalyst with excellent stability, reusability and even improved activity. The activity, selectivity and stability of this catalyst for hydroformylation of a variety of linear and branched olefinic substrates have been demonstrated. The heterogenized HRh(CO)(PPh 3) 3 catalyst was recycled several times without loss of any activity. The catalyst was characterized by powder XRD, SEM, XPS, and 31P CP MAS NMR to establish true heterogeneity and morphological characteristics.