The specific aim of this Phase I project is to purify to homogeneity acidic a-D-mannosidase from human placentas and bovine kidneys. It is anticipated that by employing a combination of chromatographic techniques on affinity, highperformance anion exchange, and/or high performance gel filtration matrices, homogeneous acidic a-D-mannosidase will be obtained. This will permit the generation of polyclonal and mono-clonal antibodies during Phase II. Furthermore, the purified enzyme and antiserum will provide a means for cloning the gene for acidic a-Dmannosidase. The absence of this enzyme in the lysosomal storage disorder, mannosidosis, which occurs in both man and cattle, makes it an ideal candidate for studying the feasibility of gene replacement therapy.National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMSD)