Investigation On Special Recognization Of Transferrin Based On Regulation Of Cyanine Dye Supermolecule

Transferrin(Tf)is an important uptake transporter in iron circulatory system.The uptake and release processes of iron ion correspond to the conformational change of Tf from closed to open.The specific identification of conformation will be the key factor in drug targeting.This specific identification method of Tf conformations by regulating cyanine dye MTC assembly,which exhibited a high sensitivity and specificity,was hoped to apply in actual serum and cell level for the monitoring and quantitative detection of Tf conformation.Based on the unique strategy of regulating different assembly states of supramolecule,a new method to recognize human transferrin(Tf)conformation was developed.We achieved to identify and to detect the open conformation of Tf(apo-Tf)in n M level against the closed one(holo-Tf)by investigating the different conditions of properties of buffer solutions,p H,tempreture and Fe3+ concentrations.Furthermore,this extrinsic probe can also monitor the transformation between the two conformations of Tf.The success of the supramolecular strategy provides a new idea for the design of protein conformational probe.It was observed that the J-aggregates,induced by β-sheet of Tf secondary structure,and the concentration of protein as an objective factor governed the transformation of MTC aggregates.The open conformational apo-h Tf mainly induced MTC into left-hand chiral J-aggregates while the closed conformational holo-h Tf could directly transfer H1-aggregates into J-dimers with electronic dislocation.The interaction mechanism between MTC and Tf was studied by fluorescence and molecular docking model.The fluorescent complexes formed in the process of MTC assembly induced by Tf and the binding affinity of MTC/apo-h Tf was higher than holoh Tf.Meanwhile,the fluorescence of Trp residues in Tf quenched by the FRET energy resonance transfer and assemble collision between MTC and Tf which resulted in the secondary structure and conformation changes of Tf.The docking results suggested that MTC located between N1 and C1 subdomains of Tf,and the Van der waals forces and hydrogen bonds were the driving forces for the interaction of MTC with Tf.The open conformation was the primary reason resulted in those phenomena.