P-alanine betaine

Quaternary ammonium compounds are important as osmoprotectants in times of water deficiency and cold stress, as well as being constituents of membrane phospholipids, p-Alanine and phosphoethanolamine are each methylated three times on their nitrogens to produce the products P-alanine betaine and phosphocholine, respectively (Fig. ll.l).24"27 An example of O-methylation and N-methylation occurring on the same molecule can be found in the indole alkaloid vindoline from Catharanthus roseus (Fig. 11.1) 28,29... 

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