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Biomedical subjects

A Bianconi

Publications and source records attributed to A Bianconi.

61 records · Page 4Linked to original sources
PubMedDate not supplied

The CO bond angle of carboxymyoglobin determined by angular-resolved XANES spectroscopy.

Our knowledge of the structure of condensed matter has been based primarily on spectroscopic methods that measure first-order pair correlations of atomic arrangements and thus provide interatomic distances (for example neutron and X-ray scattering). Bond angles are given by higher-order correlation functions, and such information can be provided by X-ray absorption near-edge structure (XANES) spectroscopy, the features of which are determined by multiple scattering of photoelectrons whose paths begin and end at the selected absorbing atom. We report here angular-resolved XANES spectroscopy of a single crystal of carboxymyoglobin (MbCO). The large dichroism of the X-ray absorption of the crystal can be fully interpreted by multiple-scattering theory which allows the determination of Fe-ligand bond angles. The analysis of the identified multiple scattering features due to CO in high signal-to-noise-ratio spectra of protein in solution has allowed the determination of the variation of CO bond angles. This opens the way to the determination of subtle structural features due to bond angle variations in proteins in solution which are relevant to an understanding of the characteristics of proteins at the atomic scale.

Carbon Monoxide↗
PubMedDate not supplied

Conformational changes involved in the switch from ovalbumin to S-ovalbumin.

For the first time a comparative study on conformational differences between native ovalbumin and its heat-stable form, called S-ovalbumin, using small angle x-ray scattering, is reported. To detect a different pathway in the folding mechanism of the two proteins, scattering measurements have been performed on ovalbumin and S-ovalbumin denatured with different concentrations of guanidine hydrochloride, and by heating the proteins at acid pH. The intensity scattering curves provide evidence that the intermediate states in the unfolding process are globular for both proteins while their compactness changes. The reported experimental results suggest that the ovalbumin to S-ovalbumin transformation can be considered a protein-switch triggered by changes in the chemical conditions of the protein environment. Because the conformational changes are likely to be of functional importance, we infer that the occurrence in vivo of S-ovalbumin is thus determined by the transformation of ovalbumin, with a functional role for embryonic development, into a new protein with a different function.

Animals↗
PubMedDate not supplied

[Epidemiologic study of functional disorders in the elderly].

Numerous observations have evidenced the high prevalence of psychosomatic disturbances in the third age, so much so that this type of pathology is second in order of frequency in the elderly. In the light of these data a study has been carried out on functional disturbances in the third age related to certain psychological and sociobiological variables. The purpose of the research was to assess the effective influence of these "extrinsic" variables in the psychosomatic disturbance observed through the psychophysiological test carried out in the different groups examined. The results of the study are discussed and some keys for interpreting the data observed are put forward.

Adult↗
PubMedDate not supplied

[The elderly and their existence model. A study with projective technics].

Elderly subjects free from psychiatric diseases and hospitalised at centres run in accordance with different models have been examined. The T.A.T. was carried out. Certain common elements emerge that would appear to be related to the senile age. Others appear to be psychological superstructures related to the different conditions of existence.

Aged↗