These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: Binding of simple carbohydrates and some N-acetyllactosamine-containing oligosaccharides to Erythrina cristagalli agglutinin as followed with a fluorescent indicator ligand.
    Author: De Boeck H, Loontiens FG, Lis H, Sharon N.
    Journal: Arch Biochem Biophys; 1984 Oct; 234(1):297-304. PubMed ID: 6548353.
    Abstract:
    Erythrina cristagalli agglutinin, a dimeric lectin [J.L. Iglesias, et al. (1982) Eur. J. Biochem. 123, 247-252] was shown by equilibrium dialysis to be bivalent for 4-methylumbelliferyl-beta-D-galactoside. Upon binding to the lectin, this ligand showed a difference absorption spectrum with two maxima (at 322 and 336 nm) of equal intensity (delta epsilon = 1.2 X 10(3) M-1 cm-1). A similar spectrum with a comparable value of delta epsilon was obtained with 4-methylumbelliferyl-N-acetyl-beta-D-galactosaminide. Binding of methyl-alpha-D-galactoside, lactose, and N-acetyllactosamine all produced small but equally intense protein difference spectra with a maximum (delta epsilon = 2.8 X 10(2) M-1 cm-1) at 291.6 nm. Upon binding of N-dansyl-D-galactosamine to the lectin, there was a fivefold increase in fluorescence intensity of this ligand. The association constant for N-dansyl-D-galactosamine was caused by a very favorable delta S degree of the dansyl group without affecting the strictly carbohydrate-specific character of binding. N-Dansyl-D-galactosamine was employed as a fluorescent indicator ligand in substitution titrations. This involved the use of simple carbohydrates, N-acetyllactosamine, and oligosaccharides which occur in the carbohydrate units of N-glycoproteins; the latter were Gal(beta 1----4)GlcNAc(beta 1----2)Man, Gal(beta 1----4)GlcNAc(beta 1----6)Man, and Gal(beta 1----4)GlcNAc(beta 1----6)[Gal(beta 1----4)GlcNAc(beta 1----2)]Man. The titrations were performed at two temperatures to determine the thermodynamic parameters. In the series N-acetyl-D-galactosamine, methyl-alpha-D-galactoside, and lactose, -delta H degrees increased from 24 to 41 kJ mol-1; it increased further for N-acetyllactosamine and then remained unchanged for the N-acetyllactosamine-containing oligosaccharides (55 +/- 1 kJ mol-1. This indicated that the site specifically accommodated the disaccharide structure with an important contribution of the 2-acetamido group in the penultimate sugar. Beyond this, no additional contacts seemed to be formed. This conclusion also followed from considerations of delta S degrees values which became more unfavorable in the above series (-23 to -101 +/- 4 J mol-1 K-1); the most negative value of delta S degrees was observed with N-acetyllactosamine and the three N-acetyllactosamine-containing oligosaccharides.
    [Abstract] [Full Text] [Related] [New Search]