title: Galactosylserine in extensin.
abstract: Cell walls obtained from tomato suspension cultures were treated at pH1 for 1h at 100 degrees C to remove arabinose oligosaccharide substituents from the hydroxyproline residues of extensin. Tryptic attack of these acid-stripped walls yielded glycopeptides containing galactose. When one of these glycopeptides (designated S(2)A(6); sequence NH(2)-Ser-Hyp-Hyp-Hyp-Hyp-Ser-Hyp-Lys-CO(2)H) was treated with (a) NaOH-NaBH(4) or (b) NaOH-Na(2)SO(3) some of the serine was converted into (a) alanine or (b) cysteic acid, and the peptide lost galactose. Maleylation or 3-carboxypropionylation of N-terminal serine was necessary for conversion of this residue and for complete loss of galactose. These results indicate that a single galactose residue is attached O-glycosidically to each of the two serine residues. Hydrazinolysis of peptide S(2)A(6) or of isolated cell walls also led to destruction of serine. In control experiments non-glycosylated serine was not destroyed during hydrazinolysis. Thus the galactosylserine linkage is sensitive to N(2)H(4).
mesh_terms: D000595:Amino Acid Sequence; D000596:Amino Acids / Q000032:analysis; D001322:Autoanalysis; D002473:Cell Wall / Q000032:analysis; D002478:Cells, Cultured; D055598:Chemical Phenomena; D002621:Chemistry; D002850:Chromatography, Gel; D002852:Chromatography, Ion Exchange; D005690:Galactose / Q000032:analysis*; D005934:Glucagon / Q000032:analysis; D006020:Glycopeptides / Q000032:analysis; D006023:Glycoproteins / Q000032:analysis*; D006027:Glycosides / Q000032:analysis; D006834:Hydrazines; D006863:Hydrogen-Ion Concentration; D006909:Hydroxyproline / Q000032:analysis; D059828:Plant Cells; D010940:Plant Proteins / Q000032:analysis*; D012694:Serine / Q000032:analysis*; D013997:Time Factors
chemical_list: D000596:Amino Acids; D006020:Glycopeptides; D006023:Glycoproteins; D006027:Glycosides; D006834:Hydrazines; D010940:Plant Proteins; D012694:Serine; D005934:Glucagon; D006909:Hydroxyproline; D005690:Galactose