The basic isoelectric form of alpha-L-fucosidase from the hepatopancreas of the shrimp Penaeus monodon (Crustacea: Decapoda).

1. alpha-L-Fucosidase was purified ca 10,889-fold to homogeneity from Penaeus monodon, with a final spec. act. of 31,250 U/mg of protein. 2. By using SDS-polyacrylamide gel electrophoresis, the monomers of shrimp alpha-L-fucosidase were discovered to have mol. wts of 63,000 and those of human placental enzyme, 46,000 and 20,000. Since the active shrimp alpha-L-fucosidase was found to have a mol. wt of 233,000 by Superose 12 FPLC, it was concluded that the purified shrimp enzyme was tetrameric. 3. In contrast to the discovery of thermolability with human placental alpha-L-fucosidase, the shrimp enzyme was found to be stable to heating at 65 degrees C for 10 min. 4. The shrimp alpha-L-fucosidase has an isoelectric point (pI) of 8.5, but the human placental enzyme has a pI of 4.0. The shrimp enzyme was sialyated. 5. The shrimp alpha-L-fucosidase has a pH optimum at 5.5 and its Km was 22.2 microM with 4-methyl-umbelliferyl-alpha-L-fucopyranoside as substrate. The human enzyme has a broad pH optimum between 5.0 and 6.5.