Enzymatic preparation of 32P-labeled beta-L-2',3',-dd-5'ATP and its use as a high-affinity, conformation-specific ligand for labeling adenylyl cyclases.

An enzymatic method was developed for the preparation of unlabeled and [beta-32P]-labeled beta-L-2',3'-dd-5'ATP from the monophosphate with near quantitative yields. beta-L-2',3'-dd-5'ATP was a competitive and potent inhibitor of adenylyl cyclases (IC5 approximately 30 nM). Upon uv-irradiation beta-L-2',3'-dd-[beta-32P]-5'ATP directly crosslinked to a chimeric construct of this enzyme. Data suggest that this is a pre-transition state inhibitor and contrasts with the equipotent 2',5'-dd-3'ATP, a post-transition state, noncompetitive inhibitor.