Negative Cooperativity Associated with Binding of Multivalent Carbohydrates to Lectins. Thermodynamic Analysis of the "Multivalency Effect"
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- 作者：Tarun K. Dam ; René ; Roy ; Daniel Pagé ; and C. Fred Brewer
- 刊名：Biochemistry
- 出版年：2002
- 出版时间：January 29, 2002
- 年：2002
- 卷：41
- 期：4
- 页码：1351 - 1358
- 全文大小：108K
- 年卷期：v.41,no.4(January 29, 2002)
- ISSN：1520-4995
文摘
Our previous study demonstrated that isothermal titration microcalorimetry (ITC) could beused to determine the thermodynamics of binding of a series of synthetic multivalent carbohydrates to theMan/Glc-specific lectins concanavalin A (ConA) and Dioclea grandiflora lectin (DGL) [Dam, T. K.,Roy, R., Das, S. K., Oscarson, S. and Brewer, C. F. (2000) J. Biol. Chem. 275, 14223-14230]. Thehigher affinities of the multivalent carbohydrates for the two lectins were shown to be due to their greaterpositive entropy of binding contributions relative to monovalent analogues. In the present study, ITC datafrom our previous report for binding of di-, tri-, and tetravalent carbohydrate analogues possessing terminal3,6-di-O-(
chars/alpha.gif" BORDER=0>-D-mannopyranosyl)-chars/alpha.gif" BORDER=0>-D-mannopyranoside residues to ConA and DGL were subjected to Hillplot analysis. Hill plots of the binding of monovalent methyl 3,6-di-O-(chars/alpha.gif" BORDER=0>-D-mannopyranosyl)-chars/alpha.gif" BORDER=0>-D-mannopyranoside to ConA and DGL are linear with slopes near 1.0, demonstrating a lack of bindingcooperativity and allosteric transitions in the proteins. However, Hill plots for the binding of the di-, tri-,and tetravalent trimannoside analogues to both lectins are curvilinear with decreasing tangent slopes below1.0, indicating increasing negative cooperativity upon binding of the analogues to the lectins. The curvilinearHill plots are consistent with decreasing affinity and functional valencies of the multivalent analoguesupon sequential binding of lectin molecules to the carbohydrate epitopes of the analogues. The followingpaper [Dam, T. K., Roy, R., Pagé, D., and Brewer, C. F. (2002) Biochemistry 41, 1359-1363] providesdirect evidence of the decreasing affinity constants of multivalent carbohydrates upon sequential bindingof lectin molecules.
chars/alpha.gif" BORDER=0>-D-mannopyranosyl)-chars/alpha.gif" BORDER=0>-D-mannopyranoside residues to ConA and DGL were subjected to Hillplot analysis. Hill plots of the binding of monovalent methyl 3,6-di-O-(chars/alpha.gif" BORDER=0>-D-mannopyranosyl)-chars/alpha.gif" BORDER=0>-D-mannopyranoside to ConA and DGL are linear with slopes near 1.0, demonstrating a lack of bindingcooperativity and allosteric transitions in the proteins. However, Hill plots for the binding of the di-, tri-,and tetravalent trimannoside analogues to both lectins are curvilinear with decreasing tangent slopes below1.0, indicating increasing negative cooperativity upon binding of the analogues to the lectins. The curvilinearHill plots are consistent with decreasing affinity and functional valencies of the multivalent analoguesupon sequential binding of lectin molecules to the carbohydrate epitopes of the analogues. The followingpaper [Dam, T. K., Roy, R., Pagé, D., and Brewer, C. F. (2002) Biochemistry 41, 1359-1363] providesdirect evidence of the decreasing affinity constants of multivalent carbohydrates upon sequential bindingof lectin molecules.