Cooperativity among manganese-binding sites in the H+-ATPase of chloroplasts.

R. Hiller*, C. Carmeli

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


Coupling factor, isolated from lettuce chloroplasts, contained several binding sites for Mn2+ ions. Three of these sites showed strong cooperative interactions having a Hill coefficient of 2.9 +/- 0.20 and a Kd of 14.7 +/- 0.44 microM. Three additional non-interacting Mn2+-binding sites were found with a Kd of 46.7 +/- 2.3 microM. Chemical modification with naphthylglyoxal of 1 arginyl residue/chloroplast coupling factor 1, which inhibited ATPase activity, inhibited the cooperativity among the sites but did not prevent Mn2+ binding to the enzyme. It is suggested that the cooperative interaction among the Mn2+-binding sites is an expression of the interaction among the active sites of the enzyme which is required for catalysis.

Original languageEnglish
Pages (from-to)1614-1617
Number of pages4
JournalJournal of Biological Chemistry
Issue number3
StatePublished - 10 Feb 1985


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