Mass spectrometric characterization of isoform variants of peanut (Arachis hypogaea) stem lectin (SL-I)

Praveen Agrawal, Saravanan Kumar, Hasi Rani Das

Research output: Contribution to journalArticlepeer-review

16 Scopus citations


Matrix assisted laser desorption/ionization-time-of-flight (MALDI-TOF) mass spectrometric (MS) analysis of purified Arachis hypogaea stem lectin (SL-I) and its tryptic digests suggested it to be an isoformic glucose/mannose binding lectin. Two-dimensional gel electrophoresis of SL-I indicated six isoforms (A1-A6), which were confirmed by Western blotting and MALDI-TOF MS analysis. Comparative analysis of peptide mass spectra of the isoforms matched with A. hypogaea lectins with three different accession numbers (Q43376_ARAHY, Q43377_ARAHY, Q70DJ5_ARAHY). Tandem mass spectrometric (MS/MS) analysis of tryptic peptides revealed these to be isoformic variants with altered amino acid sequences. Among the peptides, the peptide T12 showed major variation. The 199Val-Ser-Tyr-Asn202 sequence in peptide T12 of A1 and A2 was replaced by 199Leu-Ser-His-Glu202 in A3 and A4 (T12′) while in A5 and A6 this sequence was 199Val-Ser-Tyr-Val202 (T12″). Peptide T1 showed the presence of 10Asn in the isoforms A1-A5 while in A6 this amino acid was replaced by 10Lys (T1′). Overall amino acid sequence as identified by MS/MS showed a high degree of similarity between A1, A2 and among A3, A4, A5. Carbohydrate binding domain and adenine binding site seem to be conserved.

Original languageEnglish (US)
Pages (from-to)1573-1586
Number of pages14
JournalJournal of Proteomics
Issue number8
StatePublished - Jun 16 2010
Externally publishedYes


  • Isoform
  • Lectin
  • MS/MS based peptide sequencing
  • Mass spectrometry
  • Microheterogeneity
  • Peptide mass fingerprinting

ASJC Scopus subject areas

  • Biophysics
  • Biochemistry


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