What is "trimethylglycine"

n. (context organic chemistry English) An organic compound related to choline, with the difference that the terminal carboxylic acid group of trimethylglycine has been reduced to a hydroxyl group in choline.

Trimethylglycine (TMG) is an amino acid derivative that occurs in plants. Trimethylglycine was the first betaine discovered; originally it was simply called betaine because, in the 19th century, it was discovered in sugar beets. Since then, many other betaines have been discovered, and the more specific name glycine betaine distinguishes this one.