NMR analysis on the sialic acid-binding mechanism of an R-type lectin mutant by natural evolution-mimicry

A sialic acid-binding lectin (SRC) was created from the C-terminal domain of an R-type N-acetyl lactosamine-binding lectin (EW29Ch) by natural evolution-mimicry. Here, we clarified its sialic acid-binding mechanism using NMR spectroscopy. The NMR analysis showed differences between conformations of the 6'-sialyllactose-bound SRC in the solution state and that in the crystal state, and differences between the internal motion of the loop region in subdomain gamma in SRC and that of the corresponding region in EW29Ch. The NMR analysis thus provided useful information to explain the manner of binding to 6'-sialyllactose in solution, which the previous X-ray crystal structure analysis lacked.