JBC, Vol. 250, Issue 18, 7106-7113, Sep, 1975
Human liver alpha-L-fucosidase. Purification, characterization, and immunochemical studies
J. A. Alhadeff, A. L. Miller, H. Wenaas, T. Vedvick and J. S. O'Brien
Human liver alpha-L-fucosidase has been purified 6300-fold to apparent
homogeneity with 66% yield by a two-step affinity chromatographic procedure
utilizing agarose epsilon-aminocaproyl-fucosamine. Isoelectric focusing
revealed that all six isoelectric forms of the enzyme were purified.
Polyacrylamide gel electrophoresis of the purified alpha-L-fucosidase
demonstrated the presence of six bands of protein which all contained
fucosidase activity. The purified enzyme preparation was found to contain
only trace amounts of seven glycosidases. Quantitative amino acid analysis
was performed on the purified fucosidase. Preliminary carbohydrate analysis
indicated that only about 1% of the molecule is carbohydrate. Gel
filtration on Sepharose 4B indicated an approximate molecular weight for
alpha-L-fucosidase of 175,000 +/- 18,000. High speed sedimentation
equilibrium yielded a molecular weight of 230,000 +/- 10,000. Sodium
dodecyl sulfate polyacrylamide gels indicated the presence of a single
subunit of molecular weight, 50,100 +/- 2,500. The enzyme had a pH optimum
of 4.6 with a suggested second optimum of 6.5. Apparent Michaelis constants
and maximal velocities were determined on the purified enzyme with respect
to the 4-methylumbelliferyl and the p-nitrophenyl substrates and were found
to be 0.22 mM and 14.1 mumol/mg of protein/min and 0.43 mM and 19.6
mumol/mg of protein/min, respectively. Several salts had little or no
effect on fucosidase activity although Ag+ and Hg2+ completely inactivated
the enzyme. Antibodies made against the purified fucosidase were dound to
be monospecific against crude human liver supernatant fluids and the pure
antigen. No cross-reacting material was detected in the crude liver
supernatant fluid from a patient who died with fucosidosis.