As. Rahman et Dj. Huber, ISOLATION AND PHYSIOLOGICAL-PROPERTIES OF INTACT MITOCHONDRIA FROM BELL PEPPER (CAPSICUM-ANNUM) FRUIT, Journal of plant physiology, 149(6), 1996, pp. 677-682
A protocol for isolating mitochondria from bell pepper (Capsicum annum
, var. 'Jupiter') fruit by differential centrifugation and purificatio
n on a discontinuous 2-step Percoll gradient: was developed based on m
odifications of techniques employed for other plant tissues. The mitoc
hondrial fraction banded at the interface of the two Percoll concentra
tions, and was well separated from thylakoid fragments. Percoll-purifi
ed mitochondria exhibited high oxidative and phosphorylative capacitie
s with high respiratory control and ADP/O ratios. Catalase activity de
creased during purification of mitochondria, with levels associated wi
th purified mitochondria representing only about 3% of those present i
n crude mitochondrial fractions. The specific activity of cytochrome o
xidase increased during purification. Membrane competence of the purif
ied mitochondria was about 90%, and the typical double-membrane system
remained otherwise intact as revealed in electron micrographs. Mitoch
ondrial ATPase (alpha-subunit) and alternative oxidase proteins were d
etected at typical molecular-mass values, providing additional evidenc
e for the maintenance of mitochondrial membrane integrity during the p
urification process. Bell pepper fruit mitochondria are physiologicall
y competent in vitro and should prove useful in studies of the respira
tory metabolism of fruit ripening and senescence.