Oxidation of Reduced Nicotinamide Adenine Dinucleotide Phosphate by Potato Mitochondria

Arron, Geoffrey P.; Edwards, Gerald E.

doi:10.1104/pp.65.4.591

Cited by 36 publications

(18 citation statements)

References 17 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Mm mersalyl, whereas the NADPH oxidation is completely blocked by this inhibitor concentration (1). The present data seem, therefore, to suggest that H. tuberosus mitochondria are endowed with a nonspecific NAD(P)H dehydrogenase showing different sensitivities toward platanetin and mersalyl.…”

Section: Effect Of Uq1 On the Kinetic Parameters For Nad(p)h Oxidationmentioning

confidence: 50%

See 1 more Smart Citation

Oxidation of External NAD(P)H by Jerusalem Artichoke (Helianthus tuberosus) Mitochondria

Rugolo

Zannoni²

1992

Plant Physiol.

View full text Add to dashboard Cite

The functional interaction between the externally located NAD(P)H dehydrogenase and the Q-pool acceptor site(s) in Percoil-purified mitochondria from Jerusalem artichoke (Helianthus tuberosus L. cv OB1) mitochondria has been investigated. Oxida This phenomenon is independent of the ionic strength and it is probably due to a specific effect of polyamines on a membrane region close to the NADH-dehydrogenase/Q-pool interaction site (22).Early studies (5, 11)

show abstract

Section: Effect Of Uq1 On the Kinetic Parameters For Nad(p)h Oxidationmentioning

confidence: 50%

“…Under high ionic strength, spermine and spermidine decrease the appar- and NADPH show many similarities, they can easily be distinguished by their sensitivity to mersalyl (1). For example, NADH oxidation by potato mitochondria is insensitive to 6…”

Section: Effect Of Uq1 On the Kinetic Parameters For Nad(p)h Oxidationmentioning

confidence: 99%

Oxidation of External NAD(P)H by Jerusalem Artichoke (Helianthus tuberosus) Mitochondria

Rugolo

Zannoni²

1992

Plant Physiol.

View full text Add to dashboard Cite

show abstract

“…Oxidation of exogenous NAD(P)H is known to be Ca2+-dependent [9,21]. In future ~periments we will attempt to determine the Ca2+-requirelient of each of the two external dehydrogenases, and investiate other properties of these enzymes.…”

Section: Discussionmentioning

confidence: 99%

“…The resulting electrons enter he electron transport chain at ubiquinone bypassing Complex i, the site of rotenone inhibition [1][2][3][4][5]. Compared to NADH ~xidation, NADPH oxidation has a lower pH optimum [6][7][8], s more sensitive to thiol reagents [7,9] and appears to require nore Ca 2÷ for activity [9][10][11][12]. NADH oxidation has been re~orted to be induced in red beetroots without a concomitant nduction of NADPH oxidation [13].…”

mentioning

confidence: 99%

Direct evidence for the presence of two external NAD(P)H dehydrogenases coupled to the electron transport chain in plant mitochondria

1995

View full text Add to dashboard Cite

Exogenous NADPH oxidation by purified mitochondria from both potato tuber and Arum maculatum spadix was completely and irreversibly inhibited by sub-micromolar diphen~leneiodonium (DPI), while exogenous NADH oxidation was inhibited to only a small degree. Addition of DPI caused the collapse of the membrane potential generated by NADPH oxidation, while the potential generated by NADH was unaffected. We conclude that there are two distinct enzymes on the outer surface of the inner membrane of plant mitochondria, one specific for NADH, the other relatively specific for NADPH, with both enzymes linked to the electron transport chain.Key words: Diphenyleneiodonium; Electron transport chain; Mitochondria, plant; NAD(P)H dehydrogenase |. IntroductionUnlike mammalian mitochondria, the electron transport hain of plant mitochondria contains at least two NAD(P)H ,tehydrogenases in addition to Complex I [1]. One of these ~otenone-insensitive dehydrogenases is located on the outer , urface of the inner mitochondrial membrane, the other on the inner, matrix surface, and in the following we will refer to them ;s NDex and NDin, respectively.Due to the presence of NDex, plant mitochondria oxidize ~xogenous NADH and NADPH. The resulting electrons enter he electron transport chain at ubiquinone bypassing Complex i, the site of rotenone inhibition [1][2][3][4][5]. Compared to NADH ~xidation, NADPH oxidation has a lower pH optimum [6][7][8], s more sensitive to thiol reagents [7,9] and appears to require nore Ca 2÷ for activity [9][10][11][12]. NADH oxidation has been re~orted to be induced in red beetroots without a concomitant nduction of NADPH oxidation [13]. Likewise, mitochondria rom suspension-cultured cells of sugar beet oxidize NADH, ~ut exhibit very low rates of NADPH oxidation [14]. On the )asis of this circumstantial evidence it has been concluded that t is most likely that two separate enzymes exist, one for each ,:oenzyme [2,4,14]. However, no direct evidence has ever been r~resented to support this conclusion.Diphenyleneiodonium ( Materials and methodsMitochondria were prepared from potato (Solanum tuberosum L.) tubers according to [16]. Crude mitochondria were isolated from Arum maculatum spadices according to [17] and purified according to [18].Oxygen consumption was measured in a medium containing 0.3 M sucrose, 5 mM MOPS (pH 7.2), 5 mM KH:PO4, 2.5 mM MgCI2, 1 mM CaC12 and 0.4 ¢tM FCCP using an oxygen electrode (Rank Bros.). The membrane of the oxygen electrode was washed with 70% (v/v) ethanol between assays to avoid carry-over of DPI.Membrane potential measurements using 16 ]zM safranine as the probe were made according to [19]. The medium used was the same as that above except that FCCP was omitted, CaCI2 was 0.1 mM and 20 ,ug.mg 1 BSA was included.NAD(P)H oxidation with oxygen as the electron acceptor was assayed spectrophotometrically at 340 nm in the same medium used for the oxygen electrode measurements. Activities were calculated using an extinction coefficient for NAD(P)H of 6.2 mM -1 .cm -~, All ...

show abstract

“…Bovine serum albumin was the standard. The oxidation of exogenous NAD(P)H was measured by following the decrease in absorbance at 340 nm at room temperature (Arron and Edwards, 1980).…”

Section: Measurement Of Mitochondrial Respiration and Intactness-intactmentioning

confidence: 99%

The Role of Pyridine Dinucleotides in Regulating the Permeability of the Mitochondrial Outer Membrane

Lee¹,

Colombini

1996

Journal of Biological Chemistry

View full text Add to dashboard Cite

Both NADH and NADPH reduce the permeability of the mitochondrial outer membrane to ADP. This is specific for the outer membrane and uncorrelated with the respiratory control ratio. This could result in a 7-fold difference between the concentration of ADP in the intermembrane space and that in the external environment (at 5 M ADP). In both cases the permeability declines by a factor of 5, but NADH is more potent: K D ‫؍‬ 86 M for NADH versus 580 M for NADPH. The lower apparent affinity for NADPH is partly explained by Mg 2؉ -NADPH being the active species, and under our conditions only 30% of the NADPH is in this form. The corrected K D is 184 M. Free NADH has the same charge as the Mg 2؉ -NADPH complex, and thus both likely bind to the same site. The ability of NADH and NADPH to induce the closure of reconstituted VDAC channels is consistent with VDAC being the main pathway for metabolite flow across the outer membrane. Oncotic pressure, effective at inducing VDAC closure, also decreases the outer membrane permeability. Thus, in the presence of cytosolic colloidal osmotic pressure NAD(P)H may inhibit mitochondrial catabolic pathways and divert reducing equivalents to anabolic pathways.

show abstract

Oxidation of Reduced Nicotinamide Adenine Dinucleotide Phosphate by Potato Mitochondria

Cited by 36 publications

References 17 publications

Oxidation of External NAD(P)H by Jerusalem Artichoke (Helianthus tuberosus) Mitochondria

Oxidation of External NAD(P)H by Jerusalem Artichoke (Helianthus tuberosus) Mitochondria

Direct evidence for the presence of two external NAD(P)H dehydrogenases coupled to the electron transport chain in plant mitochondria

The Role of Pyridine Dinucleotides in Regulating the Permeability of the Mitochondrial Outer Membrane

Contact Info

Product

Resources

About