Transport of NAD in Percoll-Purified Potato Tuber Mitochondria: Inhibition of NAD Influx and Efflux by N-4-Azido-2-nitrophenyl-4-aminobutyryl-3'-NAD.
Plant physiology
confidence
Key findings
NAD transport mechanism in potato mitochondria studied; NAD influx inhibited by analog, efflux observed with uncouplers; no clinical/biological endpoints.
View source on PubMed (PMID 16664254) ↗
- Sample size
- not_reported
- Population
- Percoll-purified potato tuber mitochondria (in vitro)
- Dosing
- NAD(+) and N-4-azido-2-nitrophenyl-4-aminobutyryl-3'-NAD(+) in incubation medium
- Duration
- not_reported
- Route
- in vitro incubation
- Blinding
- not_reported
- Controls
- none
- Drug class
- coenzyme
Full abstract
A mechanism by which intact potato (Solanum tuberosum) mitochondria may regulate the matrix NAD content was studied in vitro. If mitochondria were incubated with NAD(+) at 25 degrees C in 0.3 molar mannitol, 10 millimolar phosphate buffer (pH 7.4), 5 millimolar MgCl(2), and 5 millimolar alpha-ketoglutarate, the NAD pool size increased with time. In the presence of uncouplers, net uptake was not only inhibited, but NAD(+) efflux was observed instead. Furthermore, the rate of NAD(+) accumulation in the matrix space was strongly inhibited by the analog N-4-azido-2-nitrophenyl-4-aminobutyryl-3'-NAD(+). When suspended in a medium that avoided rupture of the outer membrane, intact purified mitochondria progressively lost their NAD(+) content. This led to a slow decrease of NAD(+)-linked substrates oxidation by isolated mitochondria The rate of NAD(+) efflux from the matrix space was strongly temperature dependent and was inhibited by the analog inhibitor of NAD(+) transport indicating that a carrier was required for net flux in either direction. It is proposed that uptake and efflux operate to regulate the total matrix NAD pool size.