Chitin biosynthesis by a fungal membrane preparation. Evidence for a transient non-crystalline state of chitin.

Chitin synthase activity of membrane preparations from hyphae of Schizophyllum commune was strongly inhibited by added chitinase because chitin immediately after its synthesis was highly susceptible to chitinase. In the absence of synthesis, chitin became more resistant to chitinase with time. Chitin synthesized in the presence of the optical brightener Calcofluor White M2R was extremely susceptible to degradation by chitinase and this susceptibility was maintained for a long time. X-ray diffraction analysis of chitin synthesized in the presence of Calcofluor revealed the absence of crystallinity as long as the material was kept in wet conditions. After drying, discrete deflections characteristic for alpha-chitin appeared concomitant with a decrease in the susceptibility for chitinase. These results strongly suggest the existence of a gap between polymerization and crystallization of chitin chains.