Biology Reference
In-Depth Information
Chapter 1
Taurine, Glutathione and Bioenergetics
Svend Høime Hansen and Niels Grunnet
Abstract
Biochemistry textbook presentations of bioenergetics and mitochondrial
function normally focus on the chemiosmotic theory with introduction of the tricar-
boxylic acid cycle and the electron transport chain, the proton and electrical gradi-
ents and subsequent oxidative phosphorylation and ATP-production by ATP
synthase. The compound glutathione (GSH) is often mentioned in relation to mito-
chondrial function, primarily for a role as redox scavenger. Here we argue that its
role as redox pair with oxidised glutathione (GSSG) is pivotal with regard to con-
trolling the electrical or redox gradient across the mitochondrial inner-membrane.
The very high concentration of taurine in oxidative tissue has recently led to discus-
sions on the role of taurine in the mitochondria, e.g. with taurine acting as a pH
buffer in the mitochondrial matrix. A very important consequence of the slightly
alkaline pH is the fact that the NADH/NAD
+
redox pair can be brought in redox
equilibrium with the GSH redox pair GSH/GSSG.
An additional consequence of having GSH as redox buffer is the fact that from the
pH dependence of its redox potential, it becomes possible to explain that the mito-
chondrial membrane potential has been observed to be independent of the matrix pH.
Finally a simplified model for mitochondrial oxidation is presented with introduction
of GSH as redox buffer to stabilise the electrical gradient, and taurine as pH buffer
stabilising the pH gradient, but simultaneously establishing the equilibrium between
the NADH/NAD
+
redox pair and the redox buffer pair GSH/GSSG.
S. H. Hansen (
*
)
Department of Clinical Biochemistry , 3-01-1, Rigshospitalet,
Copenhagen University Hospital , København , Denmark
e-mail: shhansen@rh.dk
N. Grunnet
Department of Biomedical Sciences , University of Copenhagen ,
København , Denmark
