Cooperativity of Photocycle in Purple Membrane

Rafi Korenstein, Benno Hess

Research output: Contribution to journalArticlepeer-review

3 Scopus citations


This chapter discusses the kinetic coupling among bacteriorhodopsin molecules that constitutes the various clusters in the hexagonal or the orthorhombic purple membrane. To detect kinetic coupling among bacteriorhodopsin (BR) molecules both in the native hexagonal and in the orthorhombic purple membrane, it is necessary to correlate the kinetics of the thermal transitions of the photocycle with the population of a certain metastable state within a certain cluster. Because the M412 state is the longest-lived intermediate, it is possible by choosing the appropriate environmental conditions (temperature, pH, ionic strength) to obtain a high conversion yield of BRsro into M412 under photosteady light illumination, and thus by changing the light intensity to induce a variable number of BR molecules in the M412 state within a certain cluster. The dependence of the thermal decay of M412 on the occupancy of M412 is measured by turning the light off after reaching the various photostationary states of M412.

Original languageEnglish
Pages (from-to)193-201
Number of pages9
JournalMethods in Enzymology
Issue numberC
StatePublished - 1 Jan 1982


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