A simple enzyme-linked immunoassay of human carbonic anhydrase I for the study of developing erythroid cells

A simple and rapid enzyme-linked immunoassay for human erythrocyte carbonic anhydrase isozyme I was developed. The assay was found to be sensitive enough for the detection of nanogram amounts of the enzyme in incubation mixtures. The first incubation with anti-human carbonic anhydrase I IgG was carried out for 6 hours at room temperature. The second incubation of the enzyme was carried out in the presence of goat plasma C1q coupled with peroxidase for 1 h at room temperature. The enzymatic reaction was performed for 30 min using 2,2'-azino-di(3-ethyl-benzthiazoline sulfonate) as a substrate, and absorbance at 414 nm was recorded. Carbonic anhydrase I was assayed on the range of 1 to 200 ng/ml using this method. The levels of carbonic anhydrase I in K562 cells induced by erythropoietin and in other blood cells were determined. This enzyme-linked immunoassay has application for the study of developing erythroid cells.