Biomedical subjects

M Ceolín

Publications and source records attributed to M Ceolín.

4 recordsLinked to original sources

PubMed2001

Head-to-tail and side-by-side oligomerization of human carbonic anhydrase II: a small angle X-ray scattering study.

Solvent-induced directional aggregation of human carbonic anhydrase II (hCA) was studied by small angle X-ray scattering and fluorescence and fourth-derivative ultraviolet absorption spectroscopy. We propose that hCA at 5 mg ml(-1) in pure water forms head-to-tail oligomers built up, on average, by four to five monomers. At higher protein concentrations, the oligomers associate pair-wise and side-by-side. Spectroscopic evidence suggests that the subunits forming the aggregates are tightly folded, but with a structure that differs, at least locally, from the native state. A more complex aggregation pattern was observed under solvent conditions that favor the removal of zinc from the enzyme-active site, conditions under which the subunits are significantly less compact than in water. hCA may provide a useful model to investigate the effects of additives and genetic manipulation on protein aggregation.

Binding Sites↗

PubMed2000

Perturbed angular correlation experiments on the pressure-induced structural modification of bovine serum albumin.

The hydrodynamic behaviour of the bovine serum albumin (BSA) was studied by means of the Perturbed Angular Correlation (PAC) technique as a function of the hydrostatic pressure (up to 4.1 kbar) applied to the sample. The results have clearly shown that at moderated pressures (around 1.5 kbar) the BSA molecule suffers structural modifications which produces an increase of the molecular volume and the rotational correlation time of the molecule. About the reversibility of the process, our results indicate that the changes are fully irreversible. Our experiments are the first devoted to the study of the high-pressure behaviour of biological molecules using the PAC technique.

Animals↗

PubMed2000

Engineering a compact non-native state of intestinal fatty acid-binding protein.

The last three C-terminal residues (129-131) of intestinal fatty acid-binding protein (IFABP) participate in four main-chain hydrogen bonds and two electrostatic interactions to sequentially distant backbone and side-chain atoms. To assess if these interactions are involved in the final adjustment of the tertiary structure during folding, we engineered an IFABP variant truncated at residue 128. An additional mutation, Trp-6-->Phe, was introduced to simplify the conformational analysis by optical methods. Although the changes were limited to a small region of the protein surface, they resulted in an IFABP with altered secondary and tertiary structure. Truncated IFABP retains some cooperativity, is monomeric, highly compact, and has the molecular dimensions and shape of the native protein. Our results indicated that residues 129-131 are part of a crucial conformational determinant in which several long-range interactions, essential for the acquisition of the native state, are established. This work suggests that carefully controlled truncation can populate equilibrium non-native states under physiological conditions. These non-native states hold a great promise as experimental models for protein folding.

Amino Acid Substitution↗

PubMed1997

Time differential perturbed angular correlation of 111In-EDTA linked to the single free cysteine of bovine serum albumin.

By means of a facile chemical modification of the bovine serum albumin molecule, it was possible to measure its hydrodynamic radius with high accuracy (approximately 3%) using the TDPAC technique. The new approach presented here allows a wide use of the TDPAC technique to perform high precision studies of backbone dynamics of almost any protein.

Animals↗