Biomedical subjects

E Pfiffner

Publications and source records attributed to E Pfiffner.

2 recordsLinked to original sources

PubMed1987

Psychophysiological reactivity and speech behavior during the Structured Type A Interview and a self-disclosure monologue.

Speech characteristics and the simultaneously recorded psychophysiological reactivity were compared between two tape-recorded speech tests, the Structured Type A Interview (SI) and a standardized 'self-disclosure' monologue (SD) as a non-social speech test. The SD started with a 5-min mental preparation interval followed by 3 subsequent self-reports each lasting 1.5 min. The 26 students used as subjects showed in all cardiovascular parameters (interbeat interval, pulse transit time to the earlobe, finger plethysmographic amplitudes and blood pressure) strong and similar reactivity to both tests. The individual rankings of physiological reactivity turned out to be remarkably constant over all experimental periods, but this reactivity was neither correlated with the Type A scores nor with sex. Modest correlations between the SI and SD test were obtained for word rate, expiratory sighs, and silent latent pauses. Thereby, some speech variables tended to be affected by the Type A behavior, and, to a somewhat stronger extent, by sex. The desirability of a non-social speech test for assessing Type A behavior is discussed.

Adult↗

PubMed1981

Histidine at the active site of Neurospora tyrosinase.

The involvement of histidyl residues as potential ligands to the binuclear active-site copper of Neurospora tyrosinase was explored by dye-sensitized photooxidation. The enzymatic activity of the holoenzyme was shown to be unaffected by exposure to light in the presence of methylene blue; however, irradiation of the apoenzyme under the same conditions led to a progressive loss of its ability to be reactivated with Cu2+. This photoinactivation was paralleled by a decrease in the histidine content whereas the number of histidyl residues in the holoenzyme remained constant. Copper measurements of photooxidized, reconstituted apoenzyme demonstrated the loss of binding of one copper atom per mole of enzyme as a consequence of photosensitized oxidation of three out of nine histidine residues. Their sequence positions were determined by a comparison of the relative yields of the histidine containing peptides of photooxidized holo- and apotyrosinases. The data obtained show the preferential modification of histidyl residues 188, 193, and 289 and suggest that they constitute metal ligands to one of the two active-site copper atoms. Substitution of copper by cobalt was found to afford complete protection of the histidyl residues from being modified by dye-sensitized photooxidation.

Amino Acid Sequence↗