Analysis of the molecular interaction between mannosylated proteins and serum mannan-binding lectins

The kinetics and specificity of the molecular interaction between proteins modified with varying numbers of mannose residues and isolated rabbit mannan-binding lectin (MBL) were characterized by using surface plasmon resonance spectroscopy (SPR). Mannosylated bovine serum albumin (Man-BSA) with different numbers of mannoses and other mannosylated derivatives of lysozyme (LZM), soybean trypsin inhibitor (STI), superoxide dismutase (SOD) and bovine gamma-immunoglobulin (IgG) were synthesized. Rabbit MBL was isolated by affinity column chromatography and immobilized on the SPR sensor chip via avidin-biotin binding. Binding of Man-BSAs to immobilized rabbit MBL increased with an increase in the number of mannose residues, primarily due to the reduction in dissociation rate. On the other hand, the association rate constant was similar for five mannosylated proteins investigated, whereas the dissociation rate constant differed markedly in spite of the same degree of mannosylation. Specific binding of mannosylated proteins to MBL may depend on the number of mannose residues and their steric configurations.