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On the Stringent Requirement of Mannosyl Substitution in Mannooligosaccharides for the Recognition by Garlic (Allium sativum) Lectin

Bachhawat, Kiran and Thomas, Celestine J and Amutha, B and Krishnasastry, MV and Khan, MI and Surolia, Avadhesha (2001) On the Stringent Requirement of Mannosyl Substitution in Mannooligosaccharides for the Recognition by Garlic (Allium sativum) Lectin. In: The Journal of Biological Chemistry, 276 (8). pp. 5541-5546.

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The kinetics of the binding of mannooligosaccharides to the heterodimeric lectin from garlic bulbs was studied using surface plasmon resonance. The interaction of the bound lectin immobilized on the sensor chip with a selected group of high mannose oligosaccharides was monitored in real time with the change in response units. This investigation corroborates our earlier study about the special preference of garlic lectin for terminal $\alpha$ -1,2-linked mannose residues. An increase in binding propensity can be directly correlated to the addition of $\alpha$ -1,2-linked mannose to the mannooligosaccharide at its nonreducing end. Mannononase glycopeptide $(Man_9GlcNAc_2Asn)$, the highest oligomer studied, exhibited the greatest binding affinity $(K_a = 1.2 \times 10^6 M^{-1}\hspace{2mm} at\hspace{2mm} 25^oC)$. An analysis of these data reveals that the $\alpha$ -1,2-linked terminal mannose on the $\alpha$ -1,6 arm is the critical determinant in the recognition of mannooligosaccharides by the lectin. The association $(k_1)$ and dissociation rate constants $(k_{-1})$ for the binding of $Man_9GlcNAc_2Asn$ to Allium sativum agglutinin I are $6.1 \times 10^4 M^{-1} s^{-1}$ and $4.9 \times 10^{-2} s^{-1}$, respectively, at $25^oC$. Whereas $k_1$ increases progressively from $Man_3$ to $Man_7$ derivatives, and more dramatically so for $Man_8$ and $Man_9$ derivatives, $k_{-1}$ decreases relatively much less gradually from $Man_3$ to $Man_9$ structures. An unprecedented increase in the association rate constant for interaction with Allium sativum agglutinin I with the structure of the oligosaccharide ligand constitutes a significant finding in protein-sugar recognition.

Item Type: Journal Article
Publication: The Journal of Biological Chemistry
Publisher: The American Society for Biochemistry and Molecular Biology
Additional Information: Copyright of this article belongs to the American Society for Biochemistry and Molecular Biology.
Department/Centre: Division of Biological Sciences > Molecular Biophysics Unit
Date Deposited: 22 Oct 2007
Last Modified: 19 Sep 2010 04:40
URI: http://eprints.iisc.ac.in/id/eprint/12305

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