The ability of actinic light to modify the bacteriorhodopsin photocycle revisited: heterogeneity vs photocooperativity.

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TitleThe ability of actinic light to modify the bacteriorhodopsin photocycle revisited: heterogeneity vs photocooperativity.
Publication TypeJournal Article
Year of Publication2008
AuthorsHendler, RW, Shrager, RI, Meuse, CW
JournalBiochemistry
Volume47
Issue19
Pagination5406-16
Date Published2008 May 13
ISSN1520-4995
KeywordsBacteriorhodopsins, Genetic Heterogeneity, Halobacterium salinarum, Models, Biological, Photochemistry, Time Factors
Abstract

In 1995, evidence both for photocooperativity and for heterogeneity as possible explanations for the ability of actinic light to modify the kinetics and pathways of the bacteriorhodopsin (BR) photocycle was reviewed ( Shrager, R. I., Hendler, R. W., and Bose, S. (1995) Eur. J. Biochem. 229, 589-595 ). Because both concepts could be successfully modeled to experimental data and there was suggestive published evidence for both, it was concluded that both photocooperativity and heterogeneity may be involved in the adaptation of the BR photocycle to different levels of actinic light. Since that time, more information has become available and it seemed appropriate to revisit the original question. In addition to the traditional models based on all intermediates in strict linear sequences, we have considered both homogeneous and heterogeneous models with branches. It is concluded that an explanation based on heterogeneity is more likely to be the true basis for the variation of the properties of the photocycle caused by changes in actinic light intensity. On the basis of new information presented here, it seems that a heterogeneous branched model is more likely than one with separate linear sequences.

DOI10.1021/bi701749y
Alternate JournalBiochemistry
PubMed ID18422347
PubMed Central IDPMC2672163
Grant ListZ01 HL000518-04 / HL / NHLBI NIH HHS / United States