OSCP

Davy M. 2001. Terrestrial plant tests and evaluation. In FIFRA Scientific Advisory Panel Open Meeting June 27 to 29, 2001 review of non-target plant toxicity tests under NAFTA. Washington (DC) USEPA, OSCP. 

Fig. 11. A pictorial representation of the mitochondrial ATP synthesizing coupling factor interacting with the mitochondrial membrane. F, contains five polypeptide chains a, (3, 7, 8, and e and is readily solubilized. The stalk is probably made up of three polypeptide chains, 8, OSCP, and Ffi, which interact with a small group of hydrophobic polypeptides, CF0, embedded in the membrane.

Synthesis of ATP by mitochondria is inhibited by oligomycin, which binds to the OSCP subunit of ATP synthase. On the other hand, there are processes that require energy from electron transport and that are not inhibited by oligomycin. These energy-linked processes include the transport of many ions across the mitochondrial membrane (Section E) and reverse electron flow from succinate to NAD+ (Section C,2). Dinitrophenol and many other uncouplers block the reactions, but oligomycin has no effect. This fact can be rationalized by the Mitchell hypothesis if we assume that Ap can drive these processes. 

ATP synthase activity can be restored by adding back the F] complex to the depleted membranes. The F[ complexes bind to membrane channels known as the F complex, which are also composed of multiple subunits. The polypeptides of the F0 component are very hydrophobic and form a proton transport channel through the membrane, which links the proton gradient to ATP synthesis. This channel appears to be lined with hydrophilic residues such as seryl, threonyl and carboxyl groups. The stalk that connects the F, to the F complex comprises one copy each of the polypeptide known as the oligomycin-sensitivity-conferring protein (OSCP) and another protein known as F6. 

The major subunit of the FH complex is a small (Mr = 5,400) polypeptide referred to as proteolipid because of the high proportion of phospholipid bound to it. This proteolipid, now sequenced from a number of sources, forms a hairpin loop that traverses the inner mitochondrial membrane and has unique hydrophobic amino acid sequences flanking a central, short, highly charged segment that interacts with the OSCP or with F, component 5. 

For inlaid across that same membrane is Fo with protonic well Fj—ATPase stuck on it (by OSCP they tell)... 

Fig. 17. Correlation of the gas-phase free energies of ionization and oxidation potentials for unsubstituted metallocenes. The vlP for all compounds are from Ref. 154 the sources of the - and AG, values are as follows [CoCp,l and [CrCp,]. Refs. 198. 199 [NiCp ] and FeCp,. Refs. 198, 200 [OsCp l. Refs. 201. 202".

As shown in Fig. 5.2, the major portion of F, is composed of a, and y subunits, and this portion shows ATPase activity. Thus, it is the core of F,. The d and subunits of Fj constitute the portion connecting the Fj core to Fq in collaboration with the b subunit of F. In fact, the 8 subunit of prokaryotic F, is OSCP of prokaryotic Fq [32], The major portion of F is composed of a and c subunits. There are 6-10 c subunits, and each assumes hairpin shape. Evidence in support of this model will be discussed in the following sections. 

Both OsCp(CO)2l and OsCp (CO)2l are air stable yellow solids. They readily dissolve in polar solvents and are very slightly soluble in hexane. Full spectroscopic data have been reported for both complexes, and they may be conveniently characterized by their IR spectra in the carbonyl stretching region vco(hexane, abs modes), OsCp(CO)2l = 2039 (s), 1988 (s) cm Os(Cp )(CO)2l = 2020 (s), 1968 (s) cm . ... 

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