Light‐scattering spectroscopic study of polysaccharide protein conjugate

By combining gel permeation chromatography (GPC) and light‐scattering spectroscopy, including photon correlation and angular distribution of absolute scattered intensity, we were able to characterize immunologically active Haemophilus influenzae type b polysaccharide (HIB Ps) bovine serum albumin (BSA) conjugates in terms of equivalent hydrodynamic radius rh ∼ (6.2 ± 0.6) × 102 Å, apparent radius of gyration rg ∼ (5.4 ± 0.3) × 102 Å, apparent molecular weight Mw ∼ (3.5 ± 0.4) × 106 g/mol, and a second virial coefficient A2 ∼ (1.9 ± 0.3) × 10−4 cm3 mol/g2. We could study the effects of each of the processes in the conjugate formation according to the following procedure: BSA (dialysis, modification, fractionation) + HIB Ps → HIB Ps/BSA conjugate (conjugate formation, fractionation). Narrow distributions of HIB Ps BSA conjugate formation can be achieved using fractionated BSA.