Human lactoferrin (hLF), a soluble factor of the innate immune system, exhibits various biological functions and therefore has potential as a therapeutic protein. However, the clinical applications of hLF are limited by its low stability in blood. We therefore attempted to resolve this by producing recombinant hLF fused to human serum albumin (HSA).
View Article and Find Full Text PDFThe room-temperature experiment has been revisited for macromolecular crystallography. Despite being limited by radiation damage, such experiments reveal structural differences depending on temperature, and it is expected that they will be able to probe structures that are physiologically alive. For such experiments, the humid-air and glue-coating (HAG) method for humidity-controlled experiments is proposed.
View Article and Find Full Text PDFBovine cytochrome c oxidase (CcO), a 420-kDa membrane protein, pumps protons using electrostatic repulsion between protons transferred through a water channel and net positive charges created by oxidation of heme (Fe ) for reduction of O at heme (Fe ). For this process to function properly, timing is essential: The channel must be closed after collection of the protons to be pumped and before Fe oxidation. If the channel were to remain open, spontaneous backflow of the collected protons would occur.
View Article and Find Full Text PDFMitochondrial cytochrome c oxidase (CcO) transfers electrons from cytochrome c (Cyt.c) to O to generate HO, a process coupled to proton pumping. To elucidate the mechanism of electron transfer, we determined the structure of the mammalian Cyt.
View Article and Find Full Text PDFBovine heart cytochrome c oxidase (CcO) pumps four proton equivalents per catalytic cycle through the H-pathway, a proton-conducting pathway, which includes a hydrogen bond network and a water channel operating in tandem. Protons are transferred by HO through the water channel from the N-side into the hydrogen bond network, where they are pumped to the P-side by electrostatic repulsion between protons and net positive charges created at heme a as a result of electron donation to O bound to heme a To block backward proton movement, the water channel remains closed after O binding until the sequential four-proton pumping process is complete. Thus, the hydrogen bond network must collect four proton equivalents before O binding.
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