Isolation of two novel mannan- and L-fucose-binding lectins from the green alga Enteromorpha prolifera: biochemical characterization of EPL-2.
EPL-1 and EPL-2 represent lectins isolated from the green alga Enteromorpha prolifera. Both lectins are 20- to 22-kDa single-chain, nonglycosylated proteins. N-terminal sequence analysis of peptides representing over 70% of their primary structures shows that EPL-1 and EPL-2 represent novel proteins. Sedimentation-diffusion equilibrium experiments showed that EPL-1 and EPL-2 had average apparent molecular masses of 60000+/-6000 Da (EPL-1) and 59500+/-3000 Da (EPL-2), indicating that EPL-1 and EPL-2 have a tendency to self-associate into higher order aggregates, possibly homodimers and homotetramers, in equilibrium. The carbohydrate-binding specificity of EPL-2 was studied by enzyme-linked lectin assay and intrinsic fluorescence measurements. The results show that the combining site of EPL-2 is capable of accommodating both D-mannose and L-fucose, which share the conformation of the hydroxyl groups at positions 2 (axial) and 4 (equatorial), and includes subsites for the substituents at O1 and for branched mannose residues.
Ambrosio
Andrea L
AL
Instituto de Química y Fisicoquímica Biológicas (UBA-CONICET), Facultad de Farmacia y Bioquímica, Junin 956, 1113 Buenos Aires, Argentina.
Sanz
Libia
L
Sánchez
Eduardo I
EI
Wolfenstein-Todel
Carlota
C
Calvete
Juan J
JJ
D000595:Amino Acid Sequence; D000460:Chlorophyta / Q000737:chemistry* / Q000145:classification / Q000378:metabolism*; D005643:Fucose / Q000737:chemistry; D008351:Mannans / Q000737:chemistry; D008358:Mannose / Q000737:chemistry; D008969:Molecular Sequence Data; D008970:Molecular Weight; D037121:Plant Lectins / Q000737:chemistry* / Q000145:classification / Q000302:isolation & purification*; D011485:Protein Binding; D016415:Sequence Alignment / Q000379:methods*; D020539:Sequence Analysis, Protein; D013045:Species Specificity
D008351:Mannans; D037121:Plant Lectins; D005643:Fucose; D008358:Mannose