Inhibition and activation of wheat embryo calcium-dependent protein kinase and inhibition of avian myosin light chain kinase by long chain aliphatic amphiphiles

Abstract

Wheat embryo Ca 2+-dependent protein kinase (CDPK) is inhibited by a variety of long chain amphiphilic compounds that also inhibit avian myosin light chain kinase (MLCK), namely by straight chain alkylamines, alkyltrimethylammonium halides and N- alkyl-N,N- dimethyl-3- ammonio-1- propane- sulfonates . These compounds also interact with calmodulin as assessed from enhancement of Ca 2+-dependent dansyl-calmodulin fluorescence. A further common feature of these inhibitors is a greatly decreased inhibitory effectiveness at alkyl carbon chain length ≤ 12. Long chain acylcholines with acyl carbon chain length greater than 12 inhibit wheat germ CDPK but long chain acyl carnitines are ineffective. Acylcarnitines activate CDPK in the presence and absence of Ca 2+. d-Sphingosine and dihydrosphingosine inhibit both avian MLCK and plant CDPK. Sodium alkysulphates at about 10 −4 M inhibit MLCK but not plant CDPK. Dihydrosphingosine and sodium alkysulphates activate wheat germ CDPK in the presence and absence of Ca 2+.