Open Accessα 1 Acid Glycoprotein: a Small‐Angle Neutron Scattering Study of a Human Plasma Glycoprotein
Author(s) -
LI ZongQi,
PERKINS Stephen J.,
LOUCHEUXLEFEBVRE Marie H.
Publication year - 1983
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1983.tb07147.x
Subject(s) - radius of gyration , chemistry , glycoprotein , glycan , crystallography , orosomucoid , small angle neutron scattering , neutron scattering , globular protein , solvent , scattering , analytical chemistry (journal) , chromatography , biochemistry , organic chemistry , physics , polymer , optics
Small‐angle neutron scattering experiments on α 1 acid glycoprotein showed that it has a molecular weight of 37000 and a matchpoint of 44.7% 2 H 2 O. The molecular weight, the matchpoint and a v̄ of 0.704 ml/g are in agreement with the primary sequence and standard residue volumes for amino acids and carbohydrates. The radius of gyration R G of α 1 acid glycoprotein was found to be independent of concentration in the range 2–11 mg/ml, but increases on going from a buffer containing 0.2 M NaCl to one containing 1 M NaCl. A contrast variation study showed that the R G at infinite contrast is 2.47 nm for the expanded form and 2.19 nm for the contracted form, and that the two Stuhrmann α values are similar at 27 × 10 −5 . The latter is greater than that expected for globular proteins and are explained by the surface disposition of the five glycan chains on a core of protein in α 1 acid glycoprotein. Modelling calculations account for the two R G values in which for the expanded form the glycan chains extend out into the solvent and for the contracted form they either fold back or are splayed out such that they are able to interact with the surface of the protein core.