Purification of theN-acetylglucosaminide ?(1?3/4) fucosyltransferase of human milk

Abstract

TheN-acetylglucosaminide α(1–3/4)fucosyltransferase has been purified 1.8×10⁶-fold from human milk by ion-exchange chromatography, affinity chromatography of GDP-agarose and HPLC. The α(1–3/4)fucosyltransferase behaves in gel filtration-HPLC as a molecule of M_r 98 000, and differs from the α(1–3)fucosyltransferase which behaves like a molecule of about M_r 47 000. The enzyme is a glycoprotein, and the purified preparation appears in SDS polyacrylamide gel electrophoresis as a band of M_r 44 000. The results present the first purification of human milk α(1–3/4)fucosyltransferase to apparent homogeneity, and suggest that the α(1–3/4)- and α(1–3)fucosyltransferases of human milk differ in their native molecular sizes, the former being a dimer of two subunits.