Diabetes, Vol 34, Issue 8 808-811, Copyright © 1985 by American Diabetes Association
Recognition of human insulin and proinsulin by monoclonal antibodies
MJ Storch, KG Petersen, T Licht and L Kerp
High-affinity monoclonal antibodies (MAB) were obtained from lymph node
cell fusions. Affinities ranging from 0.8 X 10(9) L/M to 5.2 X 10(9) L/M
were calculated from binding studies with monoiodinated human, bovine, and
porcine insulins and human proinsulin. Two monoclonal antibodies were
specific for human insulin, recognizing an epitope involving the amino acid
B-30 (Thr). Another two monoclonal antibodies were bound to the C-terminal
end of the B-chain near B-30. The B-chain-specific monoclonal antibodies
did not bind human proinsulin. One monoclonal antibody recognized the
A-chain loop in the positions A-8 to A-10. This antibody bound also to
human proinsulin. It was concluded that the A-chain loop is exposed on the
surface of proinsulin, while the C-terminal B-chain is not available for
binding. The study shows that monoclonal antibodies can be used to
characterize structures of insulin and proinsulin. In contrast to x-ray
studies, the molecules can be used at low concentrations in soluble form.
It is suggested to use monoclonal antibodies for the screening of atypical
insulins in the serum of diabetic patients and for the further refinement
of insulin and proinsulin measurements.