BIOCHEMISTRY OF CELLULOSE BIOSYNTHESIS.

Recent advances in our understanding of cellulose biosynthesis in bacteria and higher plants are summarized. In the bacterium Acetobacter xylinum, high rates of in vitro synthesis can now be obtained as a result of the discovery that the enzyme system is activated by a cyclic guanyldinucleotide. Small fibrils averaging 17A in diameter are synthesized by the solubilized, activated enzyme. In higher plants, no convincing synthesis of cellulose using isolated enzyme systems has been achieved; instead, such preparations are quite active in synthesis of callose left bracket (1 yields 3)- beta -glucan right bracket . A receptor protein for a herbicide which specifically inhibits cellulose synthesis has been identified. This protein may regulate the rate of cellulose synthesis in plants.