Investigation On The Supramolecular Probe For Visual Identification Of Transferrin Conformation

Transferrin?hTf?is an essential transport protein delivering circulation irons to the blood and tissues.It will be formed a closed conformation with irons and specifically binds with the receptor through endocytosis.The process of capture and release irons corresponds to closed conformation and open conformation,respectively,which is closely related to its physiological functions,for example,targeted delivery drugs.Therefore,it is necessary to find a simpler,quicker and specific method to identify hTf.Cyanine dyes as one of the oldest classes of synthetic compounds are susceptible to regulation by biological macromolecules.Based on a cyanine dye supramolecular assembly,the quantitative and visual detection of hTf were finished,promising the potential application of detection hTf in cells or organisms.The researches are as follows:1)By studying the effects of pH and temperature on the system,a new probe for hTfs detection based on a cyanine dye supramolecular assembly was designed.Only using the UV-Vis spectroscopy,the specific recognition of apo-hTf was achieved.The detection limit of apo-hTf was 2.8 nM.In certain conditions,apo-hTf could induced the ETC aggregations transferred from H-band to J-band following with the color change from pink to blue,while holo-hTf hardly possessed the ability.Besides,it had a high affinity to apo-hTf(10⁷ M^-1).To further examine the suitability,iron ions were added into apo-hTf to stimulate conformation changes.It had been confirmed through tryptophan internal fluorescence quenching and the decrease of ETC J-aggregation.The potential in practical applications of this method have been tested for detection apo-hTf in human blood serum.2)In the real serum system,only 30%of hTf is saturated.The identification and conformation of natural hTf were monitored by cyanine dye ETC in serum system.The regulation ability of 30%-hTf and cyanine dye was between apo-hTf and holo-hTf.In the present study,there was a good linear relationship for 30%-hTf detection in the range of 1-5?M with a detection limit of 0.1?M.Moreover,in such complicated serum system,ETC still has the ability to reflect hTf conformation.Thus,it possible to further achieve conformational monitoring in humans or cells.Figure 47;Table 6;Reference 107.