Kinetic studies of chromaffin granule H+-ATPase and effects of bafilomycin A1

Hironori Hanada, Yoshinori Moriyama, Masatomo Maeda, Masamitsu Futai

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118 Citations (Scopus)


Vacuolar type H+-ATPase purified from bovine chromaffin granules did not show simple Michaelis-Menten type kinetics, and had apparent Km values of 5 μM, 30 μM and 300 μM. These three Km values suggested the presence of catalytic cooperativity during steady-state hydrolysis. The single turnover rate was 10-3 -fold the maximal velocity of the enzyme and similar to the rate estimated from the velocity of steady-state hydrolysis with the smallest Km value (5 μM). The H+-ATPase was inhibited by the stoichiometric binding of bafilomycin A1, a specific inhibitor of vacuolar type H+-ATPase. This inhibitor not only lowered the rate of ATP hydrolysis at the single catalytic site, but also affected the catalytic cooperativity of the enzyme.

Original languageEnglish
Pages (from-to)873-878
Number of pages6
JournalBiochemical and Biophysical Research Communications
Issue number2
Publication statusPublished - Jul 31 1990

ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Molecular Biology
  • Cell Biology


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