Covalent attachments of 5(6) acylchloride fluorescein and 5(6) thiophenol fluorescein compounds with hen egg white lysozyme and serum bovine albumin as bioorthogonal reactions

Bioorthogonal reactions are known as types of chemical reactions without the interference from biological reactions within the living systems. The requirements for such reactions include activities in aqueous environment, mild temperature, and physiological pH. One of the facile ways, for detecting bioorthogonal reactions, is covalently attaching a florescent compound to biomolecules such as proteins. In this work, two novel derivatives of fluorescein, 5(6)acylchloride fluorescein and 5(6)thiophenol fluorescein, were synthesized. The products were confirmed using 1H NMR. Subsequently, the reactions of the synthesized derivatives of with Bovine Serum Albumin (BSA) and Hen Egg white lysozyme (HEWL), under physiological conditions, were investigated. The advantages of reactions of the derivatives with proteins can include selectivity towards lysine, high kinetics of reactions, and low concentrations of reactants.The fluorescein-attached proteins were purified using size-exclusion chromatography and dialysis. The success of covalent attachments to proteins was confirmed using SDS-poly acrylamide gel electrophoresis. The reactivity of 5(6)thiophenol fluorescein towards BSA was investigated at pH 7 and pH 9.