Non-natural sialic acid derivatives with o-nitrobenzyl alcohol substituents for light-mediated protein conjugation and cell imaging.

Abstract

We have synthesized two sialic acid derivatives substituted with an ortho-nitrobenzyl alcohol (o-NBA) group that can undergo light-mediated conjugation with primary amines at their 5- or 9-carbon position. The o-NBA derivatives were shown to react with multiple lysine residues of human serum albumin (HSA) when exposed to 365 nm light irradiation within 10 min. The resulting sugar conjugates were characterized by mass spectroscopy and used for fluorescence-based cell imaging.