Related Experiment Video
Updated: Jan 30, 2026

Synthesis of a Deuterated Standard for the Quantification of 2-Arachidonoylglycerol in Caenorhabditis elegans
Published on: September 21, 2019
The synthesis of 125I-2-iodohistamine for radioimmunoassay
Abstract:
Recently radioactively labeled iodohistamines have been claimed to have superior shelf-life to the iodophenols more commonly used in radioimmunoassay of small molecules. This claim is based largely on theoretical considerations; no systematic study has appeared. We found that iodination of histamine on a macroscale proceeds rapidly at pH 7-8.4 to yield principally 2-iodohistamine. With a large excess of iodine, substantial diiodination can be achieved. In 0.5 N sodium hydroxide solution, triiodination produces 1,2,5-triiodohistamine; the N-I bond, however, is somewhat labile. 125I-2,5-Diiodohistamine is also somewhat unstable, having a first order decomposition rate of 1.6 X 10(-3) day-1 (t1/2, 182 days), while 125I-2-iodohistamine shows a barely perceptible change in 60 days (7.5 X 10(-5) day-1). The assignment of the first iodine introduced to C-2 is based on a comparison of the NMR spectra of monoiodohistamine and histamine. Iodination with carrier-free iodine-125 using the Hunter-Greenwood procedure (chloramine-T) produces a 76% yield of mono- and a 19% yield of diiodo product which are easily isolable by a single TLC using silica gel in the solvent system, ethanol:ethyl ether:water, 5:5:2.
More Related Videos
Related Concept Videos
Dehydration Synthesis
Dehydration synthesis (also called a condensation reaction) is the chemical process in which two molecules covalently link together to form a new molecule, along with the release of a water molecule. Many physiologically important compounds form by dehydration synthesis reactions, such as complex carbohydrates, proteins, DNA, and RNA.
Synthesis of carbohydrates
Sugar molecules are covalently linked together by dehydration synthesis. During the reaction, the hydroxyl (-OH) group from...
Synthesis and Decomposition Reactions
Lagging Strand Synthesis
There are several major differences between synthesis of the leading strand and synthesis of the lagging strand. 1) Leading strand synthesis happens in the direction of replication fork opening, whereas lagging strand synthesis happens in the...
Transfer RNA Synthesis
Each of these chemical modifications is carried by a specific enzyme, post-transcription. All of these enzymes have unique base and site-specificity. Methylation, the most common chemical modification, is carried by at least nine different enzymes, with...
meta-Directing Deactivators: –NO2, –CN, –CHO, –⁠CO2R, –COR, –CO2H
Ribosomal RNA Synthesis
Ribosome biogenesis begins with the synthesis of 5S and 45S pre-rRNAs by distinct RNA polymerases. The primary transcripts are extensively processed and modified before they are bound and folded by ribosomal proteins and assembly factors,...

