Complete primary structure of a newly characterized galactose-specific lectin from the seeds of Dolichos lablab |
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Authors: | Nagender Rao Rameshwaram Narasimha Kumar Karanam Christian Scharf Uwe Völker Siva Kumar Nadimpalli |
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Affiliation: | (1) Department of Biochemistry, School of Life sciences, University of Hyderabad, Hyderabad, 500 046, India;(2) Interfaculty Institute for Genetics and Functional Genomics, Ernst-Moritz-Arndt-University Greifswald, Friedrich-Ludwig-Jahn-Str. 15A, 17487 Greifswald, Germany;(3) Department of Otorhinolaryngology Head and Neck Surgery, Ernst-Moritz-Arndt-University Greifswald, Walther-Rathenau-Str. 43–45, 17475 Greifswald, Germany |
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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. Electronic Supplementary Material The online version of this article (doi:) contains supplementary material, which is available to authorized users. |
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Keywords: | Dolichos lablab Leguminosae Agglutinin α and β subunits Matrix-assisted laser desorption/ionisation mass spectrometry Galactose-specific seed lectin (DLL-II) Amino acid sequence |
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