Isoelectrofocusing pattern of 2‐α‐L, 3‐α‐L and 4‐α‐L fucosyltransferases from human milk and serum

cr-L-Fucosyltransferases have been detected in soluble form in human milk [ 121, serum [3,4] and as membrane-bound enzymes in human red cell ghosts [S], lymphocytes and platelets [6], stomach mucosa and submaxillary glands [7], bone marrow [8] and kidney [9]. The H-gene-specified enzyme, 2_ol-L-fucosyltransferase [lo] and the Le-gene-specified enzyme, 4++Lfucosyltransferase [ 11 ,121 are direct products of H and Le blood group genes, respectively. Both enzymes catalyze the transfer of L-fucose in e-linkage to the C-2 position of terminal non-reducing /3-D-galactosyl residue and to the C4 position of sub-terminal Nacetyl-D-glucosaminyl residue, respectively. The 3_ol-L-fucosyltransferase catalyses the transfer of L-fucose in a a-linkage to C-3 position of subterminal N-acetyl-D-glucosamine or D-glucose residue [ 1,3,7]. It has not been described as being like a specified blood group enzyme, although it is involved in the synthesis of related substances. The three enzymes have been described in milk [ 1 ,13 ,141. While the 2 and 3+-L-fucosyltransferases have been found in sera [3,4,15], the 4a-L-fucosyltransferase has not yet been detected in adult human sera from individuals carrying the Le gene [3]. The 2a-L-fucosyltransferase activity failed to appear in Bombay, Ah, Bh, Hz phenotypes [3,5,16]. The 3a-Lfucosyltransferase activity was identified in all individuals. In [ 17 ,181 fucosyltransferase activities were reported to increase in cancer patients; the elevated activities could be an indicator of malignancy. Here we report the electrofocusing properties of these transferases from human milk and sera. It was of interest to determine if the soluble transferases