Photosystem II and terminal respiratory oxidases molecular machines operating in opposite directions

10.2741/4550 ◽  
2017 ◽  
Vol 22 (9) ◽  
pp. 1379-1426 ◽  
Author(s):  
Sergey A Siletsky
Keyword(s):  
Photosystem Ii ◽  
Molecular Machines ◽  
Respiratory Oxidases

scholarly journals Proton Pumping and Non-Pumping Terminal Respiratory Oxidases: Active Sites Intermediates of These Molecular Machines and Their Derivatives

2021 ◽  
Vol 22 (19) ◽  
pp. 10852
Author(s):  
Sergey A. Siletsky ◽  
Vitaliy B. Borisov
Keyword(s):  
Active Sites ◽  
Three Dimensional ◽  
Molecular Machines ◽  
Proton Pumping ◽  
Stress Reactions ◽  
Low Oxygen ◽  
Functional Studies ◽  
Wide Range ◽  
Regulatory Cascades ◽  
Respiratory Oxidases

Terminal respiratory oxidases are highly efficient molecular machines. These most important bioenergetic membrane enzymes transform the energy of chemical bonds released during the transfer of electrons along the respiratory chains of eukaryotes and prokaryotes from cytochromes or quinols to molecular oxygen into a transmembrane proton gradient. They participate in regulatory cascades and physiological anti-stress reactions in multicellular organisms. They also allow microorganisms to adapt to low-oxygen conditions, survive in chemically aggressive environments and acquire antibiotic resistance. To date, three-dimensional structures with atomic resolution of members of all major groups of terminal respiratory oxidases, heme-copper oxidases, and bd-type cytochromes, have been obtained. These groups of enzymes have different origins and a wide range of functional significance in cells. At the same time, all of them are united by a catalytic reaction of four-electron reduction in oxygen into water which proceeds without the formation and release of potentially dangerous ROS from active sites. The review analyzes recent structural and functional studies of oxygen reduction intermediates in the active sites of terminal respiratory oxidases, the features of catalytic cycles, and the properties of the active sites of these enzymes.

Characterization of photosystem II with the atomic-force microscope

1992 ◽  
Vol 50 (2) ◽  
pp. 1146-1147
Author(s):  
Kathleen M. Marr ◽  
Mary K. Lyon
Keyword(s):  
Photosystem Ii ◽  
Atomic Force Microscope ◽  
Three Dimensional ◽  
Biologically Active ◽  
Atomic Force ◽  
Freeze Etching ◽  
Image Averaging ◽  
Oxygen Evolving ◽  
Averaging Techniques

Photosystem II (PSII) is different from all other reaction centers in that it splits water to evolve oxygen and hydrogen ions. This unique ability to evolve oxygen is partly due to three oxygen evolving polypeptides (OEPs) associated with the PSII complex. Freeze etching on grana derived insideout membranes revealed that the OEPs contribute to the observed tetrameric nature of the PSIl particle; when the OEPs are removed, a distinct dimer emerges. Thus, the surface of the PSII complex changes dramatically upon removal of these polypeptides. The atomic force microscope (AFM) is ideal for examining surface topography. The instrument provides a topographical view of individual PSII complexes, giving relatively high resolution three-dimensional information without image averaging techniques. In addition, the use of a fluid cell allows a biologically active sample to be maintained under fully hydrated and physiologically buffered conditions. The OEPs associated with PSII may be sequentially removed, thereby changing the surface of the complex by one polypeptide at a time.

Involvement of protein phosphorylation in the sensitivity of photosystem II to strong illumination

1994 ◽  
Vol 92 (1) ◽  
pp. 181-187
Author(s):  
Maria T. Giardi ◽  
Josef Komenda ◽  
Jiri Masojidek
Keyword(s):  
Photosystem Ii ◽  
Protein Phosphorylation

Molecular Machines

2018 ◽  
Author(s):  
Giovanni Zocchi
Keyword(s):  
Molecular Machines

Artificial molecular machines driven by light

10.2741/2741 ◽  
2008 ◽  
Vol 13 (13) ◽  
pp. 1036 ◽  
Author(s):  
Monica Semeraro
Keyword(s):  
Molecular Machines
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