Binding of HQNO to beef-heart sub-mitochondrial particles.

1. The fluorescence spectra of HQNO (2-n-heptyl-4-hydroxyquinoline-N-oxide) in water at pH 7.5 show an emission maximum at 480 nm and an excitation maximum at 355 nm. 2. The fluorescence is enhanced by binding to bovine serum albumin, and is completely quenched by binding to sub-mitochondrial particles of beef heart. 3. Binding experiments reveal specific binding of HQNO to sub-mitochondrial particles with a dissociation constant of 64 nM and, depending on the protein concentration, a considerable amount of aspecific binding. 4. The concentration of specific binding sites for HQNO is identical with that of antimycin-binding sites. Furthermore, the presence of antimycin prevents the binding of HQNO and antimycin releases HQNO from its binding site. 5. The binding of HQNO is not sensitive to the redox state of the respiratory-chain components. 6. Inhibition of electron transfer by HQNO is caused by binding to the specific binding site. 7. The relation between inhibition of NADH or succinate oxidation and saturation of the binding site is hyperbolic. 8. The increase in the reduction level of cytochrome b on addition of HQNO in the presence of succinate and oxygen, either in the presence or absence of cyanide, does not parallel the inhibition of overall electron transfer. 9. All data can be quantitatively described and analysed using the model for electron transfer proposed by Wikström and Berden in 1972 (Wikström, M.K.F. and Berden, J.A. (1972) Biochim. Biophys. Acta 283, 403-420).

Kinetics of cytochrome b reduction in submitochondrial particles.

(1) In agreement with Eisenbach and Gutman (Eisenbach, M. and Gutman, M. (1975) Eur. J. Biochem. 52, 107--116) the reduction of cytochrome b in beef-heart submitochondrial particles by succinate in the presence of antimycin was found to be biphasic, the relative amounts of fast and slow phases being dependent on the redox state of a compound located on the oxygen side of the antimycin block. (2) HQNO is a concentration sufficiently large to saturate the specific antimycin- and HQNO-binding sites can substitute for antimycin in these experiments. (3) The rate of the slow phase of the reduction of cytochrome b is decreased under anaerobic conditions and after pretreatment with 2,3-dimercaptopropanol (BAL). (4) In the presence of antimycin and cyanide, cytochrome b-562 is, to some extent, preferentially reduced in the rapid phase and b-566 in the slow phase. (5) The previously proposed regulatory effects of redox-sensitive components X and Y on the redox level and reduction kinetics, respectively, of cytochrome b are ascribed to the role of the Fe-S protein, when it is oxidized, in producing the reductant of cytochrome b by oxidation of QH2, and by the fact that when QH2 is bound to it, the reduced Fe-S protein cannot be oxidized by its natural oxidant, cytochrome c.

[A comparative study of the expenditures on health research in 7 western countries in 1997 places the Netherlands at the bottom of the list]. / Vergelijking van de uitgaven aan gezondheidsonderzoek in 7 westerse landen in 1997: Nederland op de laatste plaats.

OBJECTIVE: To compare the expenditures on health research in the Netherlands with those in other Western countries. DESIGN: Descriptive. METHOD: The expenditures on health research in 1997 were determined for the Netherlands, the United Kingdom, Germany, Norway, Denmark, Sweden and the USA and subsequently classified into: governmental funding for research in medical faculties or clusters; grants from MHRCs and other bodies; and private funding from industry and charities. The sources of information were the total research budgets 2002 of the Dutch Ministry of Education, Culture and Science, annual reports from charities, the Dutch Central Statistical Bureau and, for foreign countries, MHRCs or comparable institutions. RESULTS: In 1997, the Netherlands spent the equivalent of 855 million US dollars on health research (extremes of the investigated countries: 382 (Norway)-32,283 (USA)). This was less than in the other countries, whether calculated per capita, in US dollars (55 (Netherlands)-159 (Sweden)), as a promillage of the gross national product (2.27 (Netherlands)-5.84 (Sweden)), or as a percentage of the total expenditures for health care (2.62 (Netherlands)-7.54 (UK)). Especially the industrial expenditures on health research in the Netherlands were low, but the governmental expenditures were also lower than in the other countries.