The Amino Acid Composition of Algal Cell Walls

Abstract

Summary: The cell walls of six different species of algae were prepared in highly purified form and their amino acid and amino sugar contents determined qualitatively. A limited number of ninhydrin-positive components was found, implying that the walls contain peptide rather than protein. In five of the algal walls, those of the Chlorella species, a Scenedesmus and a Lyngbya, there were eight amino acids found in common: aspartic acid, glutamic acid, glycine, alanine, serine, valine, leucine, isoleucine. In addition to these common amino acids, the walls contained sometimes proline or hydroxyproline and different combinations of amino sugar which were characteristic of the species. In the sixth algal wall preparation, that of Nostoc, only five of the eight common amino acids were found along with hydroxyproline. Muramic acid and diaminopimelic acid were found in Lyngbya walls but in none of the others, excepting Nostoc walls which may have contained small amounts of diaminopimelic acid. Carotenoids were found associated with crude wall preparations of som of these algae.The above is taken as evidence for the existence of wall peptide in algae