Beta-adrenergic receptor kinase 1 (betaARK1) and cyclic adenosine 5'-monophosphate-dependent protein kinase A (PKA) have structurally similar adenine-binding pockets but have different physiologic functions. To obtain specific betaARK1 inhibitors, a two step rational drug design process was used. First, a search was conducted on three-dimensional models of commercially available compounds to find compounds that fit the adenine-binding pocket of betaARK1. Second, a comparative docking study that focused on the differences between the adenine-binding pockets of the two enzymes was used to evaluate the binding specificity of each compound that inhibited betaARK1 activity. The results of these analyses yielded three betaARK1-selective inhibitor leads from 11 candidates, a hit rate for selectivity of 27%. Although the IC50 values of these compounds for betaARK1 ranged from only 1.3 x 10(-4) M to 5.6 x 10(-4) M, the compounds did not inhibit PKA at concentrations up to 1.0 x 10(-3) M. Thus, the present study shows the usefulness of a rational drug design strategy in finding specific kinase inhibitors for proteins with similar drug target binding sites.

To identify the binding domain of a new Ca2؉ antagonist semotiadil on L-type Ca 2؉ channels from skeletal muscle, photolabeling was carried out by using an azidophenyl derivative of [ 3 H]semotiadil. Photoincorporation was observed in several polypeptides of membrane triad preparations; the only specific photoincorporation was in the ␣ 1 subunit of the Ca 2؉ channel. After solubilization and purification, the photolabeled ␣ 1 subunit was subjected to proteolytic and CNBr cleavage followed by antibody mapping. Specific labeling was associated solely with the region of transmembrane segment S6 in repeat IV. Quantitative immunoprecipitation was found in the tryptic and the Lys-C/Glu-C fragments of 6.6 and 6.1 kDa, respectively. Further CNBr cleavage of the Lys-C digests produced two smaller fragments of 3.4 and 1.8 kDa that were included in the tryptic and Lys-C/ Glu-C fragments. The smallest labeled fragments were: Tyr 1350 -Met 1366 and Leu 1367 -Met 1381 containing IVS6, a possible pore-forming region. The data suggest that semotiadil binds to a region that is overlapped with but not identical to those for phenylalkylamines, dihydropyridines and benzothiazepines. The present study also provides evidence that region IV represents an important component of a binding pocket for Ca 2؉

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1996 pharmacology, medicinal chemistry, vaccines, serums pharmacology, medicinal chemistry, vaccines, serums V 1100 -282Synthesis and Evaluation of 2-(Biphenylmethyl)glutaric Acid Amide Derivatives as Neutral Endopeptidase Inhibitors.-Title derivatives like (I), obtained by literature methods are evaluated for NEP (neutral endopeptidase) inhibitory activity. The most potent compound is the less polar diastereomer of (Ia) (absolute configuration not determined). -(KANNOH.; OSANAI, K.; NISHI, T.; IINO, M.; KATAKURA, S.; FURUGOHRI, T.; WATANABE, Y.; Bioorg. Med.