Radioimmunoassay for arylsulfatase A in urine.
Purified arylsulfatase A (EC 3.1.6.1) from human urine was radioiodinated under conditions that caused no significant loss of antigenic activity. We used this labeled arylsulfatase A (specific radioactivity 4-7.5 Ci/g) together with nonlabeled enzyme and rabbit antiserum produced against homogeneous enzyme to develop a radioimmunoassay for arylsulfatase A in urine. A solid-phase, second-antibody technique (Immunobead Second Antibody; Bio-Rad Laboratories) was used to separate free enzyme from antigen-antibody complexes. The working range of the assay was 0.1-4.0 ng of enzyme; within- and between-assay CVs were around 10%, and the analytical recovery was 105.5% (SD 7.7%). The lower limit of detection was 0.08 ng of arysulfatase A per assay, substantially less than that of typical activity-based assays. Over a wide range of urinary arylsulfatase A activities, results by this method agreed well (r = 0.99) with those obtained by activity assays. We measured the enzyme in urines of 59 healthy volunteers and 92 patients with different diseases, including a group of colorectal cancer cases, to determine whether this could serve as a reliable marker for cancer of the colon; however, urinary excretion of arylsulfatase A by most patients with colon cancer was within normal limits.
Laidler
P M
PM
Ryder
K W
KW
Glick
M R
MR
Oei
T O
TO
Van Etten
R L
RL
D001667:Binding, Competitive; D002553:Cerebroside-Sulfatase / Q000652:urine*; D003110:Colonic Neoplasms / Q000201:enzymology; D006801:Humans; D005779:Immunodiffusion; D011863:Radioimmunoassay; D013429:Sulfatases / Q000652:urine*
D013429:Sulfatases; D002553:Cerebroside-Sulfatase