Solid-phase methodology has previously been applied to labeling of proteins and peptide hormones used in immunoassay with the aid of enzyme sorbent. In this publication a method based on the use of a new carrier-copolymer of maleic anhydride and butanediol divinylether is introduced. As a model, bovine serum albumin (BSA) was labeled using three different procedures: Chemical, with chloramine-T as oxidizing agent: enzymatic, in a liquid phase with lactoperoxidase (LP) and horseradish peroxidase (HRP); and enzymatic, in a solid phase with maleic anhydride butanediol divinylether-copolymer as the carrier of lactoperoxidase and horseradish peroxidase.
The lactoperoxidase-mediated iodinating activity in both the liquid and solid phases was similar (incorporating 47 and 39% for the total '?odine added, 1 mCi/lO pg BSA), while HRP was more efficient in a liquid (11%) than in a solid phase (3%).
Although the specific activity of the BSA labeled with chloramine-T was highest, this Y-labeled BSA was badly degraded during iodination. However, in either liquid or solid phase enzymatic iodinations. no degradation of the protein could be observed.
Peptide hormones, luteinizing hormone, follicle-stimulating hormone and angiotensin II, iodinated with lactoperoxidase or lactoperoxidase sorbent for radioimmunoassays reacted better than peptide hormones iodinated with chemical oxidants and remained unaltered during storage, Copyright