title: Complete structure determination of the A chain of mistletoe lectin III from Viscum album L. ssp. album.
abstract: The complete primary structure of the A chain of mistletoe lectin III (ML3A), a type II ribosome-inactivating protein, was determined using proteolytic digests of ML3A, HPLC separation of the peptides, Edman degration and MALDI-MS. Based on our results, ML3A consists of 254 amino acid residues, showing a high homology to the A chain of isolectin ML1 with only 24 amino acid residue exchanges. A striking important structural difference compared with ML1A is the lack of the single N-glycosylation site in ML3A due to an amino acid exchange at position 112 (ML1A: NL112GS ==> ML3A: T112GS). The alignment of ML3A with the A chains of ML1, isoabrins, ricin D, Ricinus communis agglutinin and three lectins, identified from the Korean mistletoe Viscum album ssp. coloratum, demonstrates the rigid conservation of all amino acid residues, responsible for the RNA-N-glycosidase activity as reported for ricin D. In addition, the fully determined primary structure of ML3A will give further information about the biological mechanism of mistletoe lectin therapy.
authors.affiliation: Abteilung für Physikalische Biochemie der Universität Tübingen, Hoppe-Seyler-Str. 4, D-72076 Tübingen, Germany.
authors.forename: Roland
authors.initials: R
authors.lastname: Wacker
authors.forename: Stanka
authors.initials: S
authors.lastname: Stoeva
authors.forename: Karola
authors.initials: K
authors.lastname: Pfüller
authors.forename: Uwe
authors.initials: U
authors.lastname: Pfüller
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Voelter
mesh_terms: D000595:Amino Acid Sequence; D037102:Lectins / Q000737:chemistry* / Q000302:isolation & purification; D013058:Mass Spectrometry; D008969:Molecular Sequence Data; D028321:Plant Preparations / Q000737:chemistry* / Q000302:isolation & purification; D010940:Plant Proteins / Q000737:chemistry* / Q000302:isolation & purification; D017434:Protein Structure, Tertiary; D054790:Ribosome Inactivating Proteins, Type 2; D016415:Sequence Alignment; D020539:Sequence Analysis, Protein; D013329:Structure-Activity Relationship; D014118:Toxins, Biological / Q000737:chemistry* / Q000302:isolation & purification; D028182:Viscum album / Q000737:chemistry*
chemical_list: D037102:Lectins; D028321:Plant Preparations; D010940:Plant Proteins; D054790:Ribosome Inactivating Proteins, Type 2; D014118:Toxins, Biological; C009674:ribosome inactivating protein, Viscum