Thermodynamic and kinetic studies on saccharide binding to soya-bean agglutinin

Swamy, Musti J.; Sastry, M V Krishna; Khan, Mubbsher Munawar; Surolia, Avadhesha

doi:10.1042/bj2340515

Cited by 20 publications

(9 citation statements)

References 25 publications

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“…The k +1 value of 1.89 × 10 4 m −1 ·s −1 is approximately four orders of magnitude slower than diffusion‐controlled processes, the k +1 values for which are in the order of 10 8 −10 9 m −1 ·s −1 [35]. However, the association rate constant obtained here for the CuTMPyP–TCSL interaction is in the same range as that observed for several lectin–saccharide systems (5 × 10 3 to 5 × 10 5 m −1 ·s −1 [24,36–42]). Such slow second‐order rate constants are usually explained by invoking the formation of an intermediate [PL i , see ] that isomerizes to form the final complex (PL*).…”

Section: Discussionsupporting

confidence: 57%

Thermodynamic and kinetic analysis of porphyrin binding to Trichosanthes cucumerina seed lectin

Kenoth

Reddy

Maiya

et al. 2001

European Journal of Biochemistry

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The interaction of several metallo-porphyrins with the galactose-specific lectin from Trichosanthes cucumeirna (TCSL) has been investigated. Difference absorption spectroscopy revealed that significant changes occur in the Soret band region of the porphyrins upon binding to TCSL and these changes have been monitored to obtain association constants (K a ) and stoichiometry of binding (n ). The dimeric lectin binds two porphyrin molecules and the presence of the specific saccharide lactose did not affect porphyrin binding significantly, indicating that the sugar and the porphyrin bind at different sites. The K a values obtained for the binding of different porphyrins with TCSL at 25 8C were in the range of 2 Â 10 3 25 Â 10 5 M 21 . Association constants for meso-tetra(4-sulphonatophenyl)porphyrinato copper(II) (CuTPPS), a porphyrin bearing four negative charges and meso-tetra(4-methylpyridinium)porphyrinato copper(II) (CuTMPyP), a porphyrin with four positive charges, were determined at several temperatures; from the temperature dependence of the association constants, the thermodynamic parameters change in enthalpy (DH8) and change in entropy (DS8) associated with the binding process were estimated. The thermodynamic data indicate that porphyrin binding to TCSL is driven largely by a favourable entropic contribution; the enthalpic contribution is very small, suggesting that the binding process is governed primarily by hydrophobic forces. Stopped-flow spectroscopic measurements show that binding of CuTMPyP to TCSL takes place by a single-step process and at 20 8C, the association and dissociation rate constants were 1.89 Â 10 4 M 21 : s 21 and 0.29 s 21 , respectively.

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Section: Discussionsupporting

confidence: 57%

Thermodynamic and kinetic analysis of porphyrin binding to Trichosanthes cucumerina seed lectin

Kenoth

Reddy

Maiya

et al. 2001

European Journal of Biochemistry

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“…The values of Δ S in the SGSL–sugar interactions are far more negative than those reported for most other lectins [1, 26–29]. However, for some lectin–carbohydrate interactions, such as jacalin binding to GalNAc, T‐antigen and MeUmbαGal, Coccinia indica agglutinin binding to Umb(GlcNAc) 2 , winged bean basic lectin binding to MeUmbβGal, and wheat germ agglutinin binding to (GlcNAc) 2 or (GlcNAc) 3 , such highly negative values for Δ S have been reported [1, 24, 30–32].…”

Section: Discussionmentioning

confidence: 87%

Thermodynamic analysis of saccharide binding to snake gourd (Trichosanthes anguina) seed lectin

Komath¹,

Kenoth

Swamy

2001

European Journal of Biochemistry

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The interaction of different saccharides with the snake gourd (Trichosanthes anguina) seed lectin (SGSL) was investigated by fluorescence spectroscopy. Binding of 4-methylumbelliferyl-b-d-galactopyranoside (MeUmbb Gal) to SGSL resulted in a significant increase in the fluorescence emission intensity of the sugar at 376 nm, and this change was used to estimate the association constants for the binding interaction. Interestingly, the increase in emission intensity changed with a change in temperature, increasing from 19.2% at 20 8C to 80.2% at 40 8C. At 20 8C the association constant, K a , for the MeUmbbGal±SGSL interaction was found by fluorescence titration to be 5.8 Â 10 4 m 21 . From the temperature dependence of the association constants, the changes in enthalpy (DH) and entropy (DS) associated with binding of MeUmbbGal to SGSL were estimated to be 280.85 kJ´mol 21 and 2184.0 J´mol 21´K21 , respectively. Binding of unlabeled sugars was investigated by monitoring the decrease in fluorescence intensity when they were added to a mixture of SGSL and MeUmbbGal. The K a values for different sugars were determined at several temperatures, and DH and DS were determined from the van't Hoff plots. Enthalpy±entropy compensation was noticed in all cases. The results indicate that saccharide binding to SGSL is enthalpy-driven and the negative contribution from entropy is, in general, quite high.Keywords: agglutinin; enthalpy±entropy compensation; fluorescence spectroscopy; 4-methylumbelliferyl-b-dgalactopyranoside; thermodynamic analysis.The extraordinary diversity in their recognition of carbohydrate structures and their ubiquitous distribution in the plant and animal kingdoms make lectins a very interesting and unusual group of proteins [1]. To date, a large number have been isolated from different plant sources, and in terms of sheer numbers they greatly outweigh lectins from other sources such as viruses, bacteria, fungi or animals [2]. Plant lectins are used extensively in purification and structural characterization of glycoconjugates, investigation of cell-surface architecture, blood typing, and fractionation of cells [3,4].As a variety of biological recognition processes are mediated via lectins or lectin-like molecules and their corresponding receptors, the study of lectin±sugar interactions is of utmost importance in the characterization of any new lectin [1]. Such information is essential for assessing the affinity of a protein for a given ligand. A knowledge of the differences in binding affinity of a lectin for different sugars helps to define the architecture of the combining site of the lectin and identify the functional groups of the sugar that make positive contributions to the interaction (for examples, see [5,6]). Further, thermodynamic studies can reveal the effect of increasing the carbohydrate chain length/branching and the effect of substituents on lectin recognition [7,8]. Given the strength and specificity of the interaction, lectin±carbohydrate binding studies also provide ideal models for stu...

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“…Among the various mono and disaccharides investigated, p NPβGal exhibited the strongest affinity for TCA‐I, which appears to be most likely due to additional interactions of the aromatic aglycon with a hydrophobic pocket in the neighbourhood of the binding site. Hydrophobic aglycons or substituents on sugars have been reported to stabilize their interaction with a number of lectins (11, 23, 25, 33, 36, 49–51). Fucose is only half as potent as galactose, clearly showing that the C‐6 hydroxyl group of galactose makes a positive contribution in the binding of carbohydrate with the lectin.…”

Section: Resultsmentioning

confidence: 99%

Purification and physicochemical characterization of two galactose‐specific isolectins from the seeds of Trichosanthes cordata

2009

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SummaryA galactose-specific lectin has been purified from the seeds of Trichosanthes cordata by affinity chromatography on crosslinked guar gum. The affinity-eluted lectin could be resolved into two isolectins, TCA-I and TCA-II by ion-exchange chromatography on DEAE cellulose. The molecular weights of the isolectins were determined as 59 and 52 kDa by SDS-PAGE. TCA-I is a heterodimer in which the two subunits with masses of 32 and 27 kDa, are covalently connected by disulfide bonds. TCA-I and TCA-II are glycoproteins with 6.2% and 6.8% covalently bound neutral sugar, respectively. CD spectroscopic studies indicate that the two isolectins are very similar in secondary structure and contain about 8 to 10% a-helix, 37-38% b-sheet, 20% b-turns, and 32-33% unordered structures. These isolectins have similar carbohydrate specificities as revealed by hemagglutination-inhibition assays. Carbohydrate specificity, subunit size and composition, and secondary structure of TCA isolectins suggest close similarity to type-II ribosome inactivating proteins. The agglutination activity of TCA-I was found to be highest in the pH range 7.0-8.0. The lectin activity was unaffected between 0 and 408C, but decreased dramatically above 408C. Association constant for the interaction of TCA-I with lactose was determined by monitoring ligand-induced changes in the protein intrinsic fluorescence characteristics as 7.42 3 10 3 M 21 at 258C. The exposure and accessibility of the tryptophan residues of TCA-I and the effect of ligand binding on them have been probed by quenching studies employing neutral and ionic quenchers.

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Thermodynamic and kinetic studies on saccharide binding to soya-bean agglutinin

Cited by 20 publications

References 25 publications

Thermodynamic and kinetic analysis of porphyrin binding to Trichosanthes cucumerina seed lectin

Thermodynamic and kinetic analysis of porphyrin binding to Trichosanthes cucumerina seed lectin

Thermodynamic analysis of saccharide binding to snake gourd (Trichosanthes anguina) seed lectin

Purification and physicochemical characterization of two galactose‐specific isolectins from the seeds of Trichosanthes cordata

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