Mitochondria were isolated from fruit of six cultivars of apples differing in susceptibility to the physiological disorder, low temperature breakdown. The state 3 rate of succinate-dependent oxygen uptake and the motion of a spin label were measured at from 0 to 25 C. Arrhenius plots of the data showed that the apparent energy of activation of both respiration and motion of the spin label incre...

In order to investigate the protein conformation in the vicinity of the heme and the spin states of the heme-iron in dissolved hemoglobins, a nitroxide spin label was covalently attached to one of the propionic acid groups of the porphyrin ring. The optical spectra of the heme-spin labeled ferrihemoglobins were identical to those of native hemoglobins indicating that the spin labeling did not a...

In order to investigate the protein conformation in the vicinity of the heme and the spin states of the heme-iron in dissolved hemoglobins, a nitroxide spin label was covalently attached to one of the propionic acid groups of the porphyrin ring. The optical spectra of the heme-spin labeled ferrihemoglobins were identical to those of native hemoglobins indicating that the spin labeling did not a...

Electron paramagnetic resonance (EPR) is often used in the study of the orientation and dynamics of proteins. However, there are two major obstacles in the interpretation of EPR signals: (a) most spin labels are not fully immobilized by the protein, hence it is difficult to distinguish the mobility of the label with respect to the protein from the reorientation of the protein itself; (b) even i...

The amyloid β (A β) peptide is important in the context of Alzheimer's disease, since it is one of the major components of the fibrils that constitute amyloid plaques. Agents that can influence fibril formation are important, and of those, membrane mimics are particularly relevant, because the hydrophobic part of A β suggests a possible membrane activity of the peptide. We employed spin-label E...

The influence of structural changes of an abasic site in duplex DNA on noncovalent and site-directed spin labeling (NC-SDSL) of the spin label ç were examined with electron paramagnetic resonance (EPR) spectroscopy. The binding affinities of ç to sixteen different DNA duplexes containing all possible sequences immediately flanking the abasic site were determined and the results showed that the ...