Complete primary structure of a newly characterized galactose-specific lectin from the seeds of Dolichos lablab

Nagender Rao Rameshwaram, Narasimha Kumar Karanam, Christian Scharf, Uwe Völker, Siva Kumar Nadimpalli

Research output: Contribution to journalArticle

5 Scopus citations

Abstract

A new unique lectin (galactose-specific) purified from the seeds of Dolichos lablab, designated as DLL-II is a heterodimer composed of closely related subunits α and β. These were separated by SDS-PAGE and isolated by electroelution. By ESI-MS analysis their molecular masses were found to be 30.746 kDa (α) and 28.815 kDa (β) respectively. Both subunits were glycosylated and displayed similar amino acid composition. Using advanced mass spectrometry in combination with de novo sequencing and database searches for the peptides derived by enzymatic and chemical cleavage of these subunits, the primary sequence was deduced. This revealed DLL-II to be made of two polypeptide chains of 281(α) and 263(β) amino acids respectively. The β subunit differed from the α subunit by the absence of some amino acids at the carboxy terminal end. This structural difference suggests that possibly, the β subunit is derived from the α subunit by posttranslational proteolytic modification at the COOH-terminus. Comparison of the DLL-II sequence to other leguminous seed lectins indicates a high degree of structural conservation.

Original languageEnglish (US)
Pages (from-to)161-172
Number of pages12
JournalGlycoconjugate Journal
Volume26
Issue number2
DOIs
StatePublished - Feb 1 2009
Externally publishedYes

Keywords

  • Agglutinin
  • Amino acid sequence
  • Dolichos lablab
  • Galactose-specific seed lectin (DLL-II)
  • Leguminosae
  • Matrix-assisted laser desorption/ionisation mass spectrometry
  • α and β subunits

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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