TY - JOUR
T1 - Absence of NADH channeling in coupled reaction of mitochondrial malate dehydrogenase and complex I in alamethicin-permeabilized rat liver mitochondria
AU - Kotlyar, Alexander B.
AU - Maklashina, Elena
AU - Cecchini, Gary
N1 - Funding Information:
This work was supported by the Department of Veterans Affairs and NIH Grant GM61606.
PY - 2004/6/11
Y1 - 2004/6/11
N2 - A simple in situ model of alamethicin-permeabilized isolated rat liver mitochondria was used to investigate the channeling of NADH between mitochondrial malate dehydrogenase (MDH) and NADH:ubiquinone oxidoreductase (complex I). Alamethicin-induced pores in the mitochondrial inner membrane allow effective transport of low molecular mass components such as NAD +/NADH but not soluble proteins. Permeabilized mitochondria demonstrate high rates of respiration in the presence of malate/glutamate and NAD+ due to coupled reaction between MDH and complex I. In the presence of pyruvate and lactate dehydrogenase, an extramitochondrial competitive NADH utilizing system, respiration of permeabilized mitochondria with malate/glutamate and NAD+ was completely abolished. These data are in agreement with the free diffusion of NADH and do not support the suggestion of direct channeling of NADH from MDH to complex I.
AB - A simple in situ model of alamethicin-permeabilized isolated rat liver mitochondria was used to investigate the channeling of NADH between mitochondrial malate dehydrogenase (MDH) and NADH:ubiquinone oxidoreductase (complex I). Alamethicin-induced pores in the mitochondrial inner membrane allow effective transport of low molecular mass components such as NAD +/NADH but not soluble proteins. Permeabilized mitochondria demonstrate high rates of respiration in the presence of malate/glutamate and NAD+ due to coupled reaction between MDH and complex I. In the presence of pyruvate and lactate dehydrogenase, an extramitochondrial competitive NADH utilizing system, respiration of permeabilized mitochondria with malate/glutamate and NAD+ was completely abolished. These data are in agreement with the free diffusion of NADH and do not support the suggestion of direct channeling of NADH from MDH to complex I.
KW - Alamethicin
KW - Complex I
KW - Malate dehydrogenase
KW - Mitochondria permeabilization
KW - Mitochondrial respiration
KW - NADH:ubiquinone oxidoreductase
KW - Substrate channeling
UR - http://www.scopus.com/inward/record.url?scp=2442599389&partnerID=8YFLogxK
U2 - 10.1016/j.bbrc.2004.04.131
DO - 10.1016/j.bbrc.2004.04.131
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C2 - 15147970
AN - SCOPUS:2442599389
SN - 0006-291X
VL - 318
SP - 987
EP - 991
JO - Biochemical and Biophysical Research Communications
JF - Biochemical and Biophysical Research Communications
IS - 4
ER -