Screening Specific Binding Peptides As Drug Carrier Binder Based On Human Serum Albumin

Human Serum Albumin(HSA)is the most abundant protein in blood,which is able to transport and store large amounts of endogenous and exogenous substances and even almost every small molecule.In recent years,work with approaches like recombinant mutants and X-ray crystallography has given much new information about the ligand-binding properties of HSA,which increases the understanding of structure and function and also be of value when trying to predict ligand-ligand,ligand-drug interactions at the protein-binding level,The protein binding results in an increased solubility inplasma,decreased toxicity,and/or protection against oxidation of the bound ligand.Albumin is playing an increasing role as a drug carrier in the clinical setting.For example,the accumulation of albumin in solid tumors forms the rationale for developing albumin-based drug delivery systems for tumor targeting.Binding a therapeutic peptide or protein covalently or non-covalently to albumin enhance its stability and half-life.The therapeutic effectiveness of several bioactive peptide and protein drugs is limited by their short serum half-lives having rapid clearance by renal filtration.One approach to improve their pharmacokinetic properties is based on conjunction with a large plasma protein which has inherently long serum half-life directly to increase the molecular weight and decrease its clearance rate.Human serum albumin(HSA)can be an ideal carrier because of its unique characteristic and physiological functions.Binding technology based on the affinity has been became a means to improve the pharmaceutical properties of protein drugs.Phage display technology(PDT)since its emergence in 1985 has been successfully applied to random peptide library technology.The significant pint of HSA-based carrier is to obtain specific binding peptide,which makes us to think over on improving the panning procedure to screen phage display peptides rapidly and efficiently.Phage display technology based on phage titer was utilized to screen HSA binding phage display peptides.Specificity ratio was designed as screening parameter to optimize panning procedure quantitatively.In addition,we developed reducing the target molecule concentration method on the basis of the traditional panning strategy.Phage display peptides clones with relative higher specificity ratio were DNA sequencd and the HSA binding peptides sequences were obtained.The specificity ratio is calculated by titers of eluted phage binding in the target molecule coated plate divided by titers of eluted phage binding in the blank control plate.Through 3 rounds consecutive panning,specificity ratio was used as preliminary screening parameter to wash the HSA binding peptides.Monoclonal phages were picked out for specific identification and detected the positive clones using the phage titer successfully.Finally,we got three specific HSA peptide-binding sequences and found out that there is no homologous,it reveals that they maybe bind with different sites of HSA.The peptides screened will be used as protein drug labels,which will be bound to HSA by non-covalent to prolong the half-life and improve pharmacokinetics of protein drugs.