Near-infrared Fluorescent Labeling of L-Asparaginase

L-asparaginase, a kind of protein drug, was offered here for near-infrared labeling with a near-infrared dye called cypate. The synthesis reaction was optimized according to the investigation of dye-to-protein (D/P) ratio and enzyme activity upon different factors, such as pH value, reaction temperature, reaction duration, enzyme concentration and so on. Result indicated that the concentration of L-asparaginase and pH value played the most important role in the trial. Final D/P ratio was mainly affected by protein concentration and protein was broken at pH 9.6.