SPR Biosensing Film To Build Its Amino Acids, Chiral Recognition

As a new method for molecular interactions, surface plasmon resonance (SPR) technology has the characteristics of high sensitivity, label-free, high-throughput, low consumption. Therefore, it was widely used in life sciences, drug research through monitoring the whole process of molecular interactions in real-time.It is well known that most of amino acids, polysaccharides, proteins, DNA and other biological molecules hold chiral center, which can generate many complex chiral recognition phenomena in life processes. The stereoselectivity of chiral drugs lead to different interactions between chiral molecules and endogenous macromolecules. So, chiral recognition is great significant to biological, pharmaceutical and chemical fields.The aim of this work is to investigate the interactions between chiral molecule and protein based on SPR. Bovine serum albumin (BSA) and human serum albumin (HSA) were selected as chiral recognition probes, and different types of amino acids enantiomers were used as analysts.Firstly, the interactions between L-, D-tryptophan and BSA, HSA were studied at physiological conditions (pH7.4) with25℃. The effect of pH, protein concentration and ionic strength to protein immobilization were examined. Kinetics and equilibrium data were calculated and interaction mechanism was discussed simply. Secondly, the effect of pH, ionic strength, and temperature to binding affinity were investigated. Through thermodynamic data, the binding specificity and sites were discussed.Thirdly, the interactions of BSA and HSA with L-and D-phenylalanine, arginineacid, methionine and histidine were studied.The results showed that the interactions of proteins and each amino acid enantiomer had obviously dynamics difference. The affinity of each of L-isomers of amino acids with two proteins was greater than that of D-isomers. The binding affinity of L-tryptophan and serum albumin changed significantly greater than that of the D-isomer with different pH, ionic strength and temperature, which indicated that BSA and HSA had specific binding sites for L-tryptophan. Thermodynamic data were obtained in this experiment. The result indicated that the hydrophobic interaction played a dominant role. In addition, electrostatic interactions may certainly contribute to the interactions between L-tryptophan and serum albumin. The combination of serum albumin and D-tryptophan was non-specific adsorption. Finally, the response unit which related to molecular weight and binding specificity did not effect on the binding affinity.The study can provide an important theoretical basis for specific absorption of the chiral amino acids and drugs, which is useful for chiral recognition and drug discovery in the future.