MOLECULAR AND FUNCTIONAL-PROPERTIES OF CYTOCHROME-C FROM ADULT ASCARIS-SUUM MUSCLE

Mitochondrial cytochrome c was isolated at high purity from adult Asca ris suum muscle and its molecular properties were investigated. The mo lecular weight of A. suum cytochrome c was determined to be 13119 by e lectrospray ionization mass spectrometry. The oxidation-reduction pote ntial of nematode cytochrome c was measured to be + 248 mV; this value is comparable to those for cytochrome c from mammalian sources. The A , suum cytochrome c, like bovine heart cytochrome c, showed biphasic k inetics against bovine heart cytochrome c oxidase. Comparative kinetic studies revealed species-specificity in the reaction between cytochro me c and cytochrome c oxidase from A. suum and bovine sources. The cyt ochrome c content in mitochondria was highest at the second larval sta ge, in which the respiratory chain is the most aerobic among various d evelopmental stages of A. suum. These data clearly show that adult A. suum cytochrome c, as isolated, is a bona fide substrate for cytochrom e c oxidase in the aerobic respiratory chain of second-stage larvae.