Galectin-1 from ovine placenta

Amino-acid sequence, physicochemical properties and implications in T-cell death


  • Correspondence to C. Wolfenstein-Todel, IQUIFIB, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Junin 956, 1113 Buenos Aires, Argentina

  • Abbreviations. ConA, concanavalin A; CRD, carbohydrate-recognition domain; OPG-1, ovine placental galectin-1; PCD, programmed cell death; SpMs, spleen mononuclear cells.

  • Enzymes. Trypsin ( EC3.4.21.4); α-chymotrypsin ( EC3.4.21.1).

  • Note. The novel amino acid sequence data reported here have been deposited with the Swiss-Prot database and are available under accession number P81184.


In the present study we report the amino-acid sequence, carbohydrate specificity and overall biochemical and physicochemical properties of galectin-1, a β-galactoside-binding lectin from ovine placenta. The complete amino-acid sequence, obtained by tryptic and chymotryptic digestion, revealed that this carbohydrate-binding protein shares all the absolutely preserved and critical residues found in other members of the mammalian galectin-1 subfamily. Moreover, conformational changes induced by protein interaction with its specific disaccharide were investigated by fourth-derivative spectral analysis, intrinsic tryptophan fluorescence measurements and circular dichroism. The first two methods indicated changes in the environment of aromatic residues, in agreement with the role of Trp in carbohydrate binding. The quenching of the fluorescence emission upon addition of lactose, allowed us to calculate the Kd for its interaction with the galectin, which was 0.157 ± 0.02 mM. The far-ultraviolet CD spectra is consistent with the large extent of β-sheet structure described for other galectins. Addition of lactose produced no significant changes, suggesting that it causes no modifications in the secondary structure of the lectin. In addition, we explored its potential cell-growth inhibitory activity and implications in T-cell death. Finally, we also provide evidence showing that antagonic properties of galectins-1 and -3 are reciprocally neutralized in a natural mixture of both proteins, suggesting that they could play an important role in the regulation of cell proliferation and death, according to physiological requirements at particular developmental stages of the placenta, thus allowing successful pregnancy to occur.