Radioiodine labeling during protein synthesis

DETAILED DESCRIPTION 7.
A process for the preferential radioiodination of the tyrosyl-tRNA in an aminoacyl-tRNA mixture comprising the steps of: (a) forming a mixture comprising aminoacyl-tRNAs and sodium radioiodine in a buffered solution; (b) adding Chloramine-T to initiate the radioiodination reaction; (c) incubating the mixture at ambient temperature for a time sufficient to essentially complete radioiodination of tyrosyl-tRNA; and 8.
The process of claim 7 wherein the sodium radioiodide is sodium .
sup.
125 9.
The process of claim 7 wherein the sodium radioiodide is sodium .
sup.
131 I and the buffer solution provides a pH of about 7.
5.




Description:
This invention relates to radioiodine labeling during protein synthesis and to the use of such labeled proteins as marker compounds in analysis of physiological processes.
In one aspect, this invention relates to the preparation of the isotopic radioiodinated tyrosyl-transfer RNAs, namely .
sup.
125I-tyr-tRNA and .
sup.
131I-tyr-tRNA.
In another aspect, this invention relates to the use of such radioiodine labeled tyr-tRNA as a precursor in the synthesis of labeled proteins that are useful in chromatographic detection, immunoassay, immunoprecipitation, and serum testing procedures.
Direct iodination of protein is known in the art.
Iodine isotopes are readily introduced into purified protein by chemical or enzymatic means.
The procedure of this invention is distinguishable over prior art method in three important aspects: (1) The radioiodine labeled protein formed can be obtained unmodified by post-synthetic events such as addition of sugar residues, specific cleavage of the polypeptide chain, or reassociation into specific combinations of peptide chains.
The types and extent of such modification of the protein formed in the presence of the iodine isotopic precursor depend upon the type of broken cell preparation used.
Thus, whereas chemical or enzymatic radioiodination is carried out with mature, fully modified protein as isolated from tissue or serum, the iodine labeling in the process of this invention occurs during synthesis before the aforementioned modifications