N-(6-Aminohexyl)-5-chloro-1-naphthalenesulfonamide(W-7), a calmodulin antagonist, also inhibits phospholipid-sensitive calcium-dependent protein kinase.

N-(6-Aminohexyl)-5-chloro-1-naphthalenesulfonamide(W-7), commonly regarded as a calmodulin antagonist, inhibited phospholipid-sensitive Ca2+ -dependent protein kinase and to a lesser extent cyclic GMP- and cyclic AMP-dependent protein kinases. Kinetic studies of the inhibition of the homogeneous spleen phospholipid-sensitive Ca2+ -dependent protein kinase indicated that W-7 inhibited the enzyme activity competitively with respect to phospholipid (Ki = 60 microM). N-(6-Aminohexyl)-1-naphthalenesulfonamide (W-5) was found to be much less potent than W-7. The findings indicate that W-7 was able to inhibit a variety of protein kinases, in addition to those requiring calmodulin previously reported.