Inhibition of Membrane-Bound Adenosine Triphosphatase Activity from Nicotiana tabacum L. Leaves with Alkyltrimethylammonium Bromide

Cetyltrimethylammonium bromide (CTAB), a cationic detergent,more effectively inhibited the activity of membrane-bound epidermaladenosine triphosphatase (ATPase) of tobacco (Nicotiana tabacumL. cv. Samsun) leaves than anionic or non-ionic detergents.The inhibition of ATPase activity was highly dependent on thelength of the alkyl chain of alkyltrimethylammonium: CTAB >dodecyltrimethylammonium bromide > n-octyltrimethylammoniumbromide trimethylammonium chloride cetyl bromide, comparedat 10^–4 M. The last three derivatives hardly inhibitedthe activity. CTAB inhibition was equivalent to that due toother cationic detergents, cetylpyridinium bromide and cetylamine, but less than that by gramicidin S and tyrocidine andstronger than that by N,N'-dicyclohexylcarbodiimide and vanadate. These results show that a certain length of the alkyl chain(C_n>12) and the combination of both hydrophobic and chargedgroups of a detergent moiety are indispensable for inhibitingthe membrane-bound epidermal ATPase activity. (Received January 26, 1982; Accepted April 10, 1982)