J. Biol. Chem., Vol. 259, Issue 18, 11169-11172, Sep, 1984
Dicyclohexylcarbodiimide binds to cytochrome b and subunit VIII in soluble complex III from beef heart mitochondria
L Clejan, CG Bosch and DS Beattie
Incubation of soluble complex III isolated from either yeast or beef heart
mitochondria with 25-100 nmol of [14C]dicyclohexylcarbodiimide (DCCD)/nmol
of cytochrome b followed by centrifugation through 10% sucrose or
precipitation with trichloroacetic acid did not result in any changes in
the appearance of the subunits of either complex. The [14C]DCCD was bound
to cytochrome b and phospholipids in the yeast complex and with similar
kinetics to both cytochrome b and subunit VIII (Mr = 4000-8000) plus
phospholipids of the beef complex. Subunit VIII of the beef complex was
partially extracted with chloroform:methanol; however, no subunit of this
mobility was present in the yeast complex. Incubation of the beef complex
in phosphate buffer for short times resulted in a doubling of the [14C]DCCD
bound to cytochrome b relative to that to subunit VIII. Preincubation of
both complexes with venturicidin prior to treatment with DCCD resulted in a
50% decrease in the binding of [14C]DCCD to cytochrome b. Reisolation of
the beef complex III by precipitation with (NH4)2SO4 after incubation with
[14C]DCCD resulted in the formation of a new band with an apparent
molecular weight of 39,000 even in the zero time control. The [14C]DCCD was
bound to subunit VIII and the core proteins but not to cytochrome b at all
times, suggesting that precipitation with (NH)2SO4 in the presence of DCCD
causes cross-linking of the subunits of complex III.
CiteULike 
Complore 
Connotea 
Del.icio.us 
Digg 
Reddit 
Technorati What's this?
