Preparation and preliminary X‐ray studies of three acidic pH crystal forms of the anti‐T lectin from peanut (<i>Arachis hypogaea</i>)

Salunke, Dinakar M.; Khan, Mubbsher Munawar; Surolia, Avadhesha; Vijayan, M.

doi:10.1016/0014-5793(83)80262-2

Cited by 12 publications

(6 citation statements)

References 9 publications

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“…Crystals of the PNA–lactose complex, suitable for X‐ray analysis, were grown at pH 4.6 under conditions described earlier 21. Although the triclinic crystal form was characterized previously,21 the monoclinic crystal form reported here is new. Crystallization attempts at lower pH ranges failed to yield diffracting crystals.…”

Section: Methodsmentioning

confidence: 93%

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Crystal structures of the peanut lectin–lactose complex at acidic pH: Retention of unusual quaternary structure, empty and carbohydrate bound combining sites, molecular mimicry and crystal packing directed by interactions at the combining site

et al. 2001

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The crystal structures of a monoclinic and a triclinic form of the peanut lectin-lactose complex, grown at pH 4.6, have been determined. They contain two and one crystallographically independent tetramers, respectively. The unusual "open" quaternary structure of the lectin, observed in the orthorhombic complex grown in neutral pH, is retained at the acidic pH. The sugar molecule is bound to three of the eight subunits in the monoclinic crystals, whereas the combining sites in four are empty. The lectin-sugar interactions are almost the same at neutral and acidic pH. A comparison of the sugar-bound and free subunits indicates that the geometry of the combining site is relatively unaffected by ligand binding. The combining site of the eighth subunit in the monoclinic crystals is bound to a peptide stretch in a loop from a neighboring molecule. The same interaction exists in two subunits of the triclinic crystals, whereas density corresponding to sugar exists in the combining sites of the other two subunits. Solution studies show that oligopeptides with sequences corresponding to that in the loop bind to the lectin at acidic pH, but only with reduced affinity at neutral pH. The reverse is the case with the binding of lactose to the lectin. A comparison of the neutral and acidic pH crystal structures indicates that the molecular packing in the latter is directed to a substantial extent by the increased affinity of the peptide loop to the combining site at acidic pH.

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Section: Methodsmentioning

confidence: 93%

“…The protein was prepared by affinity chromatography on crosslinked arabinogalactan 20. Crystals of the PNA–lactose complex, suitable for X‐ray analysis, were grown at pH 4.6 under conditions described earlier 21. Although the triclinic crystal form was characterized previously,21 the monoclinic crystal form reported here is new.…”

Section: Methodsmentioning

confidence: 99%

Crystal structures of the peanut lectin–lactose complex at acidic pH: Retention of unusual quaternary structure, empty and carbohydrate bound combining sites, molecular mimicry and crystal packing directed by interactions at the combining site

et al. 2001

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“…[42][43][44][45] There is a key stacking interaction between the aromatic ring of Tyr125 and the hydrophobic a-face patch of the galactose unit of the disaccharide. Further hydrogen bonds are Asp80 Od2-Gal O6 and that involving Ser211 Oc.…”

Section: Structural Featuresmentioning

confidence: 99%

Lectins: Tools for the Molecular Understanding of the Glycocode

2005

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Recent progress in glycobiology has revealed that cell surface oligosaccharides play an essential role in recognition events. More precisely, these saccharides may be complexed by lectins, carbohydrate-binding proteins other than enzymes and antibodies, able to recognise sugars in a highly specific manner. The ubiquity of lectin-carbohydrate interactions opens enormous potential for their exploitation in BA (1993) and DPhil (1996) T h i s j o u r n a l i s © T h e R o y a l S o c i e t y o f C h e m i s t r y

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“…The single chain in each subunit is 236 amino acid residues long and is homologous to the subunits in other legume lectins (Young & Oomen, 1992). The protein in association with lactose was first crystallised at neutral pH in an orthorhombic form (Salunke et al, 1982) and then at acidic pH in two monoclinic forms and one triclinic form (Salunke et al, 1983). All of them contained a tetramer in the asymmetric unit.…”

Section: Introductionmentioning

confidence: 99%

Conformation, Protein-Carbohydrate Interactions and a Novel Subunit Association in the Refined Structure of Peanut Lectin-Lactose Complex

Banerjee

Das

Ravishankar

et al. 1996

Journal of Molecular Biology

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171

162

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The structure of the complex of the tetrameric peanut lectin with lactose has been refined to an R-value of 16.4% using 2.25 Å resolution X-ray Indian Institute of Science diffraction data. The subunit conformation in the structure is similar to that Bangalore-560 012, India in other legume lectins except in the loops. It has been shown that in the tertiary structure of legume lectins, the short five-stranded sheet plays a major role in connecting the larger flat six-stranded and curved seven-stranded sheets. Furthermore, the loops that connect the strands at the two ends of the seven-stranded sheet curve toward and interact with each other to produce a second hydrophobic core in addition to the one between the two large sheets. The protein-lactose interactions involve the invariant features observed in other legume lectins in addition to those characteristic of peanut lectin. The ''open'' quaternary association in peanut lectin is stabilised by hydrophobic, hydrogen-bonded and water-mediated interactions. Contrary to the earlier belief, the structure of peanut lectin demonstrates that the variability in quaternary association in legume lectins, despite all of them having nearly the same tertiary structure, is not necessarily caused by covalently bound carbohydrate. An attempt has been made to provide a structural rationale for this variability, on the basis of buried surface areas during dimerisation. A total of 45 water molecules remain invariant when the hydration shells of the four subunits are compared. A majority of them appear to be involved in stabilising loops.

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Preparation and preliminary X‐ray studies of three acidic pH crystal forms of the anti‐T lectin from peanut (Arachis hypogaea)

Abstract: not received Peanut lectinNew crystal form X-ray analysis

Cited by 12 publications

References 9 publications

Crystal structures of the peanut lectin–lactose complex at acidic pH: Retention of unusual quaternary structure, empty and carbohydrate bound combining sites, molecular mimicry and crystal packing directed by interactions at the combining site

Crystal structures of the peanut lectin–lactose complex at acidic pH: Retention of unusual quaternary structure, empty and carbohydrate bound combining sites, molecular mimicry and crystal packing directed by interactions at the combining site

Lectins: Tools for the Molecular Understanding of the Glycocode

Conformation, Protein-Carbohydrate Interactions and a Novel Subunit Association in the Refined Structure of Peanut Lectin-Lactose Complex

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