ANALYSIS OF THE SUBUNITS, ISOFORMS AND SUBSTRATE-SPECIFICITY OF MOUSE-LIVER ALPHA-L-FUCOSIDASE

1. SDS-PAGE indicates the presence of two major protein bands (57 and 62 kDa) for mouse fucosidase and Western blotting indicates that both bands are immunoreactive with polyclonal antibodies (PAbs) and/or mono clonal antibodies (MAbs) raised against human liver fucosidase. The le ctins SNA and GNA recognized both mouse protein bands, indicating that both subunits are glycosylated and contain sialic acid residues. 2. P olyacrylamide gel-isoelectric focusing (PAG-IEF) indicated that mouse liver fucosidase contains at least seven isofoms, with three isoforms above pI 6.0, which were not detected in human liver fucosidase. Blott ing indicates that the PAbs recognized seven mouse fucosidase isoforms (pIs 3.6-6.8) whereas the four MAbs did not appear to recognize any o f the mouse isoforms. 3. The subunit composition of the separated isof orms of mouse alpha-L-fucosidase was investigated by SDS-PAGE. One-to- two closely-spaced protein bands are found in each isoform with a tren d of increasing relative amounts of the high-M(r) band in the more aci dic isoforms relative to the more neutral isoforms. 4. Human and mouse liver alpha-L-fucosidases hydrolyze L-Fuc from oligosaccharides and g lycolipids at comparables rates, with the exception of ganglioside Fuc -G(M1) which was hydrolyzed by human, but not by mouse, alpha-L-fucosi dase.