The lichenin extracted by water from Iceland moss has been obtained free from isolichenin and submitted to partial acidic hydrolysis. An examination of the products confirms that the lichenin is an unbranched β-glucan in which 1:4- and 1:3-links occur together in the same molecule. It is calculated that the ratio of 1:4- to 1:3-links lies between 2:1 and 3:1. Evidence is presented which suggests that the lichenin chain is a repeating sequence of β-cellotriose units joined through 1:3-bonds. Comment is made on a possible route of the biosynthesis of lichenin. The β-glucan extractable by cold water from oats has been examined by the same methods and shown to be structurally identical with the lichenin of Iceland moss. The oat lichenin is not, however, associated with an isolichenin.
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