Abstract
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 125iodine added, 1 mCi 10 μ g 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 125I-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.
Published Version
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