Biomedical subjects
Publications and source records attributed to A Giovane.
Explore the source record for details and available documents.
Translational elongation factor G (EF-G) of Escherichia coli was modified with the selective, site-specific lysine reagent pyridoxal phosphate (PLP). The reaction results in the modification of a maximum of 12 lysine residues, one of which is essential for guanosine 5'-triphosphate (GTP) binding and whose modification is inhibited by the presence of GTP. Formation of a reversible adduct between 2,3-butanedione and an essential arginine similarly located in the GTP binding site [Rohrbach, M.S., & Bodley, J. W. (1977) Biochemistry 16, 1360-1363] also protects EF-G from PLP inactivation, suggesting that these two residues are spatially close to each other in the native factor. The essential lysine residue was found in the trypsin-resistant fragment T4 (Mr 41 000). In addition to the lysine essential for GTP binding, at least one further lysine was found to be important for EF-G function, since GTP-protected, PLP-modified EF-G molecules fully competent in binding to 50S ribosomal subunits showed decreased activity in 50S- and 70S-dependent GTP hydrolysis. It is likely that a PLP-modified lysine impairs the interaction of the factor with 30S ribosomal subunits and/or a conformational change of the factor required for the hydrolysis of GTP.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
The myoglobin content in the hearts of several fishes is positively correlated with the ecological physiology of the species. In the tuna heart, where the highest myoglobin values are found, the logarithmic relationship between myoglobin content and body weight is reported.
Second derivative spectroscopy has been used to resolve the complex protein spectrum in the near-ultraviolet region and the contributions of the three aromatic chromophores have been evaluated. A method for the direct quantitative determination of phenylalanine and tryptophan in proteins has been carried out. Phenylalanine determination has been carried out in the spectral region between 250 and 265 nm, where there are no significant contributions from other aromatic chromophores. Tryptophan determination has been performed in the 290-295-nm region and the experimental values have been corrected for the presence of tyrosine. The results obtained on 10 highly purified proteins have been found in good agreement with those obtained from sequence analysis.
1. The heart ventricle myoglobin of Atlantic bluefin tuna has been purified and its amino acid composition has been determined. 2. The perturbing effect of guanidine hydrochloride on the molecular structure of tuna ferrimyoglobin and its corresponding apoprotein has been investigated by Soret absorbance and ultraviolet fluorescence. 3. The conformation-free energy of unfolding delta G0 has been calculated by thermodynamic treatments of the data concerning guanidine unfolding. 4. The results have been compared with other known myoglobins, particularly those of yellowfin tuna.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
The report presents a rare case of intestinal duplication in a 43-year old female. Intestinal duplication is a rare congenital malformation and is extremely exceptional in adults. A lot of etiopathogenic theories have been advanced to explain this malformation that can occur anywhere along the alimentary tract, even if the ileum remains the most common. It may be cystic or tubular. An important aspect of mucosal histology is the possibility of gastric heterotopy, conditioning a particular treatment. The literature shows 14 cases with clinical very different presentations and instrumental exams were rarely helpful for correct diagnosis. Treatment of choice is surgical complete resection of the duplication. When contiguous structures are involved intestinal bypass or Roux-on-Y anastomosis may be necessary with mandatory stripping of the mucosa when heterotopic gastric mucosa is present in order to prevent the risk of gastrointestinal haemorrhage or malignant transformation, an event possible in about 25% of the cases reported in the literature.