Lipid-Linked Intermediates in Crustacean Chitin Synthesis

Abstract

In the arthropods, chitin is associated with protein ^1,2. Although a structural role for the protein seems clear, a biosynthetic function is also possible, eg the protein may serve in the initial formation of a primer molecule. Regarding the origin of chitin synthesis primers, Cabib and co-workers found that partially purified chitin synthetase from Saccharomyces does not require an exogenous primer for chitin synthesis to occur.³ Similar results have been reported by Cohen⁴ who studied the in vitro synthesis of insect chitin. In both studies, the chitin synthetase preparation appears to contain an endogenous primer. Previous studies in my laboratory have shown that crustacean chitin synthetase will utilize both oligosaccharides of chitin and macromole- cular chitin as substrates.⁵ The crustacean enzyme is similar to its fungal counterpart in several respects, e.g., antibiotic sensitivity, but is clearly different in lacking protease activation properties and not being stimulated by GlcNAc.