Figure 5.
Guanine deaminase activity is disrupted by substrate analogues. (A) Lysates (50 μg) from COS-7 cells expressing GFP and GFP-cypin with guanine analogues (10μM) in DMSO were examined using the Amplex Red dye in a colorimetric GDA assay (n = 3). Lysates from cells expressing GFP do not contain GDA activity and were used as a negative control. (B) Purified rabbit GDA (8×10-4U) with guanine analogues (10μM) in DMSO was subjected to a GDA assay as in (A). Standard error is shown for each data point. Note that some standard error values are smaller than the data symbols.