Hydroxyproline Glycosides in Secretory Arabinogalactan-Protein of Phaseolus vulgaris L.

The carbohydrate moiety of secretory arabinogalactan protein in bean seedlings (Phaseolus vulgaris L. cv. Prélude) is attached to the peptide backbone through hydroxyproline, serine, and threonine. Hydroxyproline-linked side chains, consisting of arabinose, galactose, glucose, and rhamnose, comprise the major part of the sugar residues. These hydroxyproline glycosides differ from those in non-extractable cell wall protein but show similarities with those in wall protein of the alga Chlamydomonas.