Several
N-acetyllactosamine (LacNAc) derivatives were tested as acceptors for alpha 1,3-L-fucosyltransferase present in human
ovarian cancer sera and ovarian
tumor. The
enzyme of the soluble fraction of
tumor was purified to apparent homogeneity by chromatography on bovine
IgG glycopeptide-
Sepharose followed by
Sephacryl S-200 (M(r) < 67,000). As compared with 2'-methyl LacNAc, 3'-sulfo LacNAc was about 5-fold more sensitive in measuring alpha 1,3-fucosyltransferase in sera (Km, 3'-sulfo LacNAc, 0.12 mM; 2'-methyl LacNAc, 6.67 mM). When
ovarian cancer serum was the
enzyme source, either the
sulfate group or a sialyl moiety at C-3' of LacNAc enhanced the acceptor ability (341 and 242%, respectively), whereas the
sulfate group at C-2' or C-6' reduced the activity (22-36%);
sulfate at C-6 or
fucose at C-2' increased the activity (172 and 253%). The beta-benzylation of the reducing end, in general, increased the activity 2-3-fold. The
enzyme of the soluble fraction of
tumor exhibited more activity toward 3'-sulfo LacNAc (447%), 2'-fucosyl-LacNAc (436%), and 6-sulfo LacNAc (272%). Very low activity was observed with 3'-sialyl LacNAc (12.4%), 2'-sulfo LacNAc (33%), and 6'-sulfo LacNAc (5%); Fuc alpha 1,2Gal beta 1,3GlcNAc beta-O-p-nitrophenyl (166%), 2-methyl Gal beta 1,3GlcNAc beta-O-benzyl (204%), and 3-sulfo Gal beta 1,3GlcNAc (415%) also acted as acceptors, indicating the coexistence of alpha 1,3- and alpha 1,4-fucosyltransferase. The
tumor particulate
enzyme behaved entirely different, exhibiting low activity with 3'-sulfo LacNAc (39%) and 2'-fucosyl-LacNAc (148%); 3'-sialyl, 6'-sulfo, 6-sulfo, or 2'-sulfo LacNAc were 3, 43, 53, and 10% active, respectively. Thus, the
ovarian cancer serum alpha 1,3-fucosyltransferase acts equally well on H-type 2,3'-sialyl LacNAc and 3'-sulfo LacNAc, but not on H-type 1. The
enzyme of soluble
tumor fraction acts on H-type 2,3'-sulfo LacNAc as well as H-type 1 but poorly on 3'-sialyl LacNAc. The
tumor particulate
enzyme acts on H-type 2 but poorly on 3'-sulfo or 3'-sialyl LacNAc and is inactive with H-type 1. When normal serum was examined with synthetic acceptors, > 80% activity was found as alpha 1,2-fucosyltransferase and the rest as alpha 1,3-fucosyltransferase. A screening of 21
ovarian cancer and 3 normal sera (3'-sulfo LacNAc as acceptor) showed 17-572% increase (average increase, 188%) of alpha 1,3-fucosyltransferase activity in
cancer.(ABSTRACT TRUNCATED AT 400 WORDS)