alexa A high redox potential form of cytochrome c550 in photosystem II from Thermosynechococcus elongatus.


Clinical Microbiology: Open Access

Author(s): Guerrero F, Sedoud A, Kirilovsky D, Rutherford AW, Ortega JM,

Abstract Share this page

Abstract Cytochrome c(550) (cyt c(550)) is a component of photosystem II (PSII) from cyanobacteria, red algae, and some other eukaryotic algae. Its physiological role remains unclear. In the present work, measurements of the midpoint redox potential (E(m)) were performed using intact PSII core complexes preparations from a histidine-tagged PSII mutant strain of the thermophilic cyanobacterium Thermosynechococcus (T.) elongatus. When redox titrations were done in the absence of redox mediators, an E(m) value of +200 mV was obtained for cyt c(550). This value is ∼300 mV more positive than that previously measured in the presence of mediators (E(m) = -80 mV). The shift from the high potential form (E(m) = +200 mV) to the low potential form (E(m) = -80 mV) of cyt c(550) is attributed to conformational changes, triggered by the reduction of a component of PSII that is sequestered and out of equilibrium with the medium, most likely the Mn(4)Ca cluster. This reduction can occur when reduced low potential redox mediators are present or under highly reducing conditions even in the absence of mediators. Based on these observations, it is suggested that the E(m) of +200 mV obtained without mediators could be the physiological redox potential of the cyt c(550) in PSII. This value opens the possibility of a redox function for cyt c(550) in PSII.
This article was published in J Biol Chem and referenced in Clinical Microbiology: Open Access

Relevant Expert PPTs

Relevant Speaker PPTs

  • Hedef Dhafir El-Yassin
    The Immune Response of Prolactin and the Induction of Tumor Necrosis Factor (TNF) in Iraqi Patients Infected with Hepatitis C Virus
    PPT Version | PDF Version
  • Ahmed Mohammed Ashshi
    The correlations of activins and follistatin with viral load, liver damage, Interleukin-6 and tumour necrosis factor-α in treatment naïve patients with chronic hepatitis C genotype 1 and 4: A case-control study
    PPT Version | PDF Version

Recommended Conferences

Relevant Topics

Peer Reviewed Journals
Make the best use of Scientific Research and information from our 700 + peer reviewed, Open Access Journals
International Conferences 2017-18
Meet Inspiring Speakers and Experts at our 3000+ Global Annual Meetings

Contact Us

© 2008-2017 OMICS International - Open Access Publisher. Best viewed in Mozilla Firefox | Google Chrome | Above IE 7.0 version