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F Bonomi

Publications and source records attributed to F Bonomi.

43 records · Page 3Linked to original sources
PubMed1980

Modulation of the flavin redox potential as mode of regulation of succinate dehydrogenase activity.

The redox properties of flavin in active and non-active (oxaloacetate reacted) soluble succinate dehydrogenase were studied. Quantitative analysis of reductive activation titrations of redox titrations of active and non-active enzyme reveal that the redox potential of the histidyl-flavin in the active enzyme (-3 +/- 15 mV) is high enough to allow reduction by succinate, whereas in the non active enzyme it is -196 +/- 19 mV, far to low to be reduced by substrate. The flavin radical in the active enzyme attains 60% of total flavin at a poised redox potential of about +60 mV, upon addition of oxaloacetate the magnitude of the signal is diminished and the potential where it reaches maximal concentration is shifted by about -200 mV. A mechanism is proposed which ascribes the fundamental difference between active and non-active enzyme to the inability of the latter to be reduced by substrate.

Animals↗
PubMed1980

REDCE: a computer program for the analysis of red cell survival data.

A computer program for the analysis of red cell survival data is described. Experimental data are used to estimate the parameters of seven models of derived from different hypotheses on the red cell destruction process. The program includes statistical tests for the reliability of the estimated parameter values and the bias due to the poor model. A set of criteria for selecting between models is given. The results obtained from simulated and red data are reported and discussed.

Computers↗
PubMed1977

Rhodanese-Mediated sulfur transfer to succinate dehydrogenase.

The interaction of the sulfurtransferase rhodanese (EC 2.8.1.1) with succinate dehydrogenase (EC 1.3.99.1), yeast alcohol dehydrogenase (EC 1.1.1.1) and bovine serum albumin was studied. Succinate dehydrogenase incorporates the sulfane sulfur of [35S]rhodanese and, in the presence of unlabelled rhodanese, also incorporates that of [35S]thiosulfate. Rhodanese releases most of its transferable sulfur and is re-loaded in the presence of thiosulfate. Rhodanese undergoes similar modifications with yeast alcohol dehydrogenase but this latter does not bind 35S in amounts comparable to those incorporated in succinate dehydrogenase: nearly all the 35S released by [35S]rhodanese is with low-molecular-weight compounds. Bovine serum albumin also binds very little sulfur and [35S]rhodanese present in the reaction mixture does not discharge its radioactive sulfur nor does it take up sulfur from thiosulfate. Sulfur release from rhodanese appears to depend on the presence of - SH groups in the acceptor protein. Sulfur incorporated into succinate dehydrogenase was analytically determined as sulfide. A comparison of the optical spectra of succinate dehydrogenase preparations incubated with or without rhodanese indicates that there is an effect of the sulfurtransferase on the iron-sulfur absorption of the flavorprotein. The interaction of rhodanese with succinate dehydrogenase greatly decreases the catalytic activity of rhodanese with respect to thiocyanate formation. This is attributed to modifications in rhodanese associated with the reduction of sulfane sulfur to sulfide. Thiosulfate in part protects from this deactivation. The reconstitutive capacity of succinate dehydrogenase increased in parallel with sulfur incorporated in that enzyme following its interaction with rhodanese.

Alcohol Oxidoreductases↗