Monofunctional Heme-Catalases
Por:
Hansberg, Wilhelm
Publicada:
1 nov 2022
Resumen:
The review focuses on four issues that are critical for the
understanding of monofunctional catalases. How hydrogen peroxide (H2O2)
reaches the active site and outcompetes water molecules to be able to
function at a very high rate is one of the issues examined. Part of the
answer is a gate valve system that is instrumental to drive out solvent
molecules from the final section of the main channel. A second issue
relates to how the enzyme deals with an unproductive reactive compound I
(Cpd I) intermediate. Peroxidatic two and one electron donors and the
transfer of electrons to the active site from NADPH and other compounds
are reviewed. The new ascribed catalase reactions are revised,
indicating possible measurement pitfalls. A third issue concerns the
heme b to heme d oxidation, why this reaction occurs only in some
large-size subunit catalases (LSCs), and the possible role of singlet
oxygen in this and other modifications. The formation of a covalent bond
between the proximal tyrosine with the vicinal residue is analyzed. The
last issue refers to the origin and function of the additional
C-terminal domain (TD) of LSCs. The TD has a molecular chaperone
activity that is traced to a gene fusion between a Hsp31-type chaperone
and a small-size subunit catalase (SSC).
Filiaciones:
Hansberg, Wilhelm:
Departamento de Biología Celular y del Desarrollo, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México (UNAM), Mexico City, 04510, Mexico
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