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A comparative study has been made on the subunits of Complex III from beef heart, rat liver, Neurospora, and baker's yeast mitochondria. All of the subunits of the beef heart enzyme were similar to the counterpart subunit in rat liver Complex III, both with respect to their apparent molecular weights on SDS-polyacrylamide gels and their proteolytic digestion maps obtained in the presence of S. subtilus V8 protease. In contrast, the subunits of Neurospora and yeast Complex III varied considerably from the mammalian enzyme, as well as between themselves, the only exception being cytochrome b (subunit III). Less variation was observed in the electron transport peptides (IV-V) of higher and lower eukaryotes than in those subunits (I, II, VI-VIII) for which no functions are known. However, the data imply that subunits I, II, and VI-VIII are bona fide members of the complex, and that their functions within the complex, although unknown, are also somewhat conserved. Finally, the low-molecular-weight subunits of rat liver cytochrome oxidase and Complex III were compared. They appear to contain no subunits in common, implying different roles for these peptides in the two complexes.

The topology of beef heart Complex III has been studied by tryptic and chymotryptic digestion of isolated Complex III, Mg2+-ATP submitochondrial particles, and mitoplasts. Degradation products were detected by the immunoreplication technique using specific antibodies against core protein 1 (50 K) and core protein 2 (47 K). It can be shown that both peptides are digested from the matrix side of the inner membrane. However, no evidence was found that these peptides were digested by trypsin or chymotrypsin from the cytoplasmic side. It is concluded that the beef heart core proteins are membrane-bound peptides containing tryptic and chymotryptic digestion sites only on the matrix surface of the inner membrane. The data also suggest that beef heart core protein 2 contains multiple domains which are inserted into the membrane from the matrix surface. Proteolytic treatment of submitochondrial particles under conditions which digested at least 50% of the core proteins from the matrix surface did not, however, influence NADH oxidation rates or the respiratory control ratios.

Concentrations of S-100 protein in cerebrospinal fluid (CSF) were measured by a recently developed radioimmunoassay (RIA) in 45 patients with subarachnoid haemorrhage (SAH), 44 with verified ruptured aneurysm. In each of 43 patients 2-15 serial CSF samples were analysed, and in the remainder 1 sample was examined. The concentrations of S-100 protein proved to be related to the brain damage caused by the SAH, indexed as outcome (Glasgow Outcome Scale). The S-100 concentrations were related to the severity of the haemorrhage and to the development of delayed ischaemic deterioration. Delayed ischaemic deterioration (vasospasm) was usually accompanied by an increase in CSF S-100 concentration after 4 days. Patients in whom no S-100 value exceeded 20 ng S-100 per ml during the course of the disease had a favourable outcome, whereas patients in whom one or several CSF samples contained more than 100 ng/ml became severely disabled or vegetative or died. The present study suggests that CSF S-100 analysis may be used as an objective and early measure of the degree of brain damage sustained by the SAH patient.