RESPIRATORY-CHAIN OF THE LUNG FLUKE PARAGONIMUS-WESTERMANI - FACULTATIVE ANAEROBIC MITOCHONDRIA

The respiratory chain of adult Paragonimus westermani, a lung fluke, w as characterized in isolated micochondria. The fluke mitochondria exhi bited cyanide- and antimycin A-sensitive succinate oxidase activity at a rate of 16.8 nmol O-2 min(-1) mg(-1) protein. The succinate oxidati on was shown to be stimulated by ADP and linked to the formation of me mbrane potential. The specific activities of oxidoreductases composing the succinate oxidase system, i.e., succinate-ubiquinone and succinat e-cytochrome c oxidoreductase (complex II and complex II-III, respecti vely) and cytochrome c oxidase (complex IV), were compared in mitochon dria from adult Paragonimus, bovine heart (an aerobic tissue), and mus cle of adult Ascaris suum which possesses an anaerobic respiratory cha in. The activity values of complex II-III and complex IV were high, mi ddle, and low for bovine heart, Paragonimus, and A. suum, respectively , whereas the activity of complex II was comparable among the three so urces. The cytochrome contents of Paragonimus mitochondria as determin ed by difference absorption spectrophotometry ranged between those in Ascaris and bovine mitochondria for types c and aa(3) cytochromes. Par agonimus mitochondria exhibited a high activity of NADH-fumarate reduc tase; the specific activity was about 18-fold higher in fluke submitoc hondria than in bovine heart submitochondria. Quinone analysis by HPLC and mass spectrometry showed that the fluke mitochondria contain both rhodoquinone-10 and ubiquinone-10 at concentrations of 0.572 and 0.32 1 nmol mg(-1) mitochondrial protein, respectively. These data clearly show that mitochondria from adult P. westermani, unlike adult Ascaris mitochondria, possess both cyanide-sensitive succinate oxidase and NAD H-fumarate reductase systems, indicating that the fluke mitochondria a re facultatively anaerobic. (C) 1994 Academic Press,Inc.