Fe(III)-{di[N-(2,3-dihydroxybenzoyl)-L-seryl]-N-(C-5-[deoxy-beta-D-glucosyl]-2,3-dihydroxybenzoyl)-L-serine} + H2O + H(+) = Fe(III)-{N-(2,3-dihydroxybenzoyl)-L-seryl-N-(C-5-[deoxy-beta-D-glucosyl]-2,3-dihydroxybenzoyl)-L-serine} + N-(2,3-dihydroxybenzoyl)-L-serine — reaction