Carbohydrate binding activities of Bradyrhizobium japonicum. II. Isolation and characterization of a galactose-specific lectin.
Extracts of Bradyrhizobium japonicum were fractionated on Sepharose columns covalently derivatized with lactose. Elution of the material that was specifically bound to the affinity column with lactose yielded a protein of Mr approximately 38,000. Isoelectric focusing of this sample yielded two spots with pI values of 6.4 and 6.8. This protein specifically bound to galactose-containing glycoconjugates, but did not bind either to glucose or mannose. Derivatives of galactose at the C-2 position showed much weaker binding; there was an 18-fold difference in the relative binding affinities of galactose versus N-acetyl-D-galactosamine. These results indicate that we have purified a newly identified carbohydrate-binding protein from Bradyrhizobium japonicum, that can exquisitely distinguish galactose from its derivatives at the C-2 position.
Department of Biochemistry, Michigan State University, East Lansing 48824.
S C
SC
Ho
M
M
Schindler
J L
JL
Wang
D001667:Binding, Competitive; D050260:Carbohydrate Metabolism; D002240:Carbohydrate Sequence; D002614:Chelating Agents; D002846:Chromatography, Affinity; D005690:Galactose / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D007526:Isoelectric Point; D007785:Lactose / Q000378:metabolism; D037102:Lectins / Q000302:isolation & purification*; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009154:Mutation; D012230:Rhizobiaceae / Q000378:metabolism*; D012685:Sepharose / Q000031:analogs & derivatives
D002614:Chelating Agents; D037102:Lectins; D012685:Sepharose; D007785:Lactose; D005690:Galactose