Biomedical subjects

A Ghiretti-Magaldi

Publications and source records attributed to A Ghiretti-Magaldi.

15 recordsLinked to original sources

PubMed2001

The primary structure of globin and linker chains from the chlorocruorin of the polychaete Sabella spallanzanii.

Annelid hemoglobins are organized in a very complex supramolecular network of interacting polypeptides, the structure of which is still not wholly resolved. We have separated by two-dimensional electrophoresis the 4-MDa chlorocruorin of Sabella spallanzanii and identified its components by amino-terminal sequencing. This work reveals a high rate of heterogeneity of constituent chains in a single animal as well as in the Sabella population. Using a cDNA library prepared from the hematopoietic tissue of this worm, we have isolated and fully sequenced most globin and linker cDNAs. The primary structure features of these polypeptides have been characterized by comparison with model globin and linker sequences.

Amino Acid Sequence↗

PubMed2001

The evolution of extracellular hemoglobins of annelids, vestimentiferans, and pogonophorans.

The evolution of extracellular hemoglobins of annelids, vestimentiferans, and pogonophorans was investigated by applying cladistic and distance-based approaches to reconstruct the phylogenetic relationships of this group of respiratory pigments. We performed this study using the aligned sequences of globin and linker chains that are the constituents of these complex molecules. Three novel globin and two novel linker chains of Sabella spallanzanii described in an accompanying paper (Pallavicini, A., Negrisolo, E., Barbato, R., Dewilde, S., Ghiretti-Magaldi, A., Moens, L., and Lanfranchi, G. (2001) J. Biol. Chem. 276, 26384--26390) were also included. Our results allowed us to test previous hypotheses on the evolutionary pathways of these proteins and to formulate a new most parsimonious model of molecular evolution. According to this novel model, the genes coding for the polypeptides forming these composite molecules were already present in the common ancestor of annelids, vestimentiferans, and pogonophorans.

Amino Acid Sequence↗

PubMed1979

Hemocyanin of Octopus vulgaris. The molecular weight of the minimal functional subunit in 3 M urea.

In the presence of 3 M urea Octopus vulgaris (Mollusca) hemocyanin dissociates completely, giving a single functional component which reassociates in the original aggregate after removal of urea. The molecular weight of this subunit has been determined by gel filtration, by viscosity measurements, and by ultracentrifugation. The values obtrained with the different methods range from 247,000 to 262,000. Electron microscopy shows that the reassociation of the functional subunit after removal of urea is complete and gives the typical cylindrical structure of the native protein. This component is the minimal functional subunit which can be obtained from Octopus hemocyanin without splitting covalent bonds. It is suggested that this component is made by five protomers (50,000 daltons) containing one oxygen binding site each bound covalently through, perhaps, the carbohydrate moieties of the protein.

Animals↗

PubMed1974