Two cytosolic, acidic (pI 3.8) glycoproteins (M(r) 110,000 and 90,000) from lignifying xylem of Pinus banksiana were electrophoretically isolated and confirmed by combined gas chromatography-mass spectrometry to be capable of hydrolysing E-coniferin to trans-coniferyl alcohol. These isoenzymes yielded identical N-terminal sequences having negligible homology with documented glucosidases, suggesting that they constitute a novel form of beta-glucosidase.