Abstract:

Carbohydrates chips are powerful tools for quantitatively studying protein-carbohydrate interactions. Typically, carbohydrate chips are prepared using the self-assembly of carbohydrate thiol/disulfide, which always requires multiple hydroxyl group protection/deprotection steps resulting low conversion in the preparation. In this paper, a kind of carbohydrate derivatives containing dithiocarbamate (DTC) group was synthesized through a two-step reaction to prepare self-assembled monolayers presenting carbohydrate (glycol-DTC SAMs). The glycol-DTC SAMs was characterized using X-ray photoelectron spectroscopy (XPS) and the protein binding activity was quantitatively analysized using surface plasma resonance (SPR) and enzyme linked lectin assay (ELLA). By mixed self-assembly of carbohydrate dithiocarbamate and sarcosine dithiocarbamate, Glycol-DTC SAMs with different glucose density were prepared. The protein binding kinetics was monitored in real time and the thermodynamics was calculated. Interestingly, a 1:1 binding of concanavalin A (Con A) was obtained on the SAMs prepared in solution containing 1% glucose-DTC, as the dissociation constant (K_d) was calculated to be (39.10±0.12) μmol·L^-1. A 1:2 binding of Con A was obtained on the SAMs prepared in solutions containing >2% glucose-DTC, as the K_d was calculated to be (1.17±0.18) μmol·L^-1. By simply mixed selfassembly, multivalent binding of Con A can be realized and separate kinetic parameters can be obtained. Our work would promote the study of protein-carbohydrate interactions and be helpful for revealing the relevant biological progress.

Key words: Carbohydrate-protein interaction, Dithiocarbamate, Multivalent adsorption, Thermodynamics, Kinetics, SAM