In vitro stability and in vivo clearance of fibrinogen or serum albumin labeled with 77Br, 131I, or 125I by direct or indirect synthetic methods

Abstract

Conventional protein iodination involves the addition of an oxidizing agent to the protein solution. Through the use of the acylating agent N-succinimidyl-3(4-hydroxyphenyl)propionate, labeling can be accomplished without subjecting the protein to oxidizing conditions. Fibrinogen and serum albumin labeled with 131I and 77Br by this technique were compared with each other and with 125I-protein prepared by direct iodination using the ICI, chloramine-T, and lactoperoxidase methods. Iodinated proteins have two drawbacks: the high radiation dose accompanying 125I and 131I, and the ease of hydrolysis of the weak carbon-iodine bond. These drawbacks can be overcome by using 56-hr 77Br.