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D Barra

Publications and source records attributed to D Barra.

188 records · Page 11Linked to original sources
PubMedDate not supplied

Structural identity between the iron- and manganese-containing superoxide dismutases.

We have recently reported the first complete amino acid sequence of an iron-containing superoxide dismutase. The iron enzyme is thought to be closely homologous to the manganese-containing superoxide dismutases. The availability of complete amino acid sequence information for four manganese superoxide dismutases and the crystal structures for two iron and two manganese superoxide dismutases prompted us to investigate the degree of homology between the two proteins at various levels. We report that it is not possible to clearly distinguish the two proteins on the basis of their secondary or tertiary structures. It would appear that a small number of single site substitutions are responsible for conferring distinguishing properties between the two proteins. Substitution of glycine 77 and glutamine 154 by a glutamine and an alanine respectively in Photobacterium leiognathi iron superoxide dismutase may distinguish the kinetic and other particular properties of this protein from the manganese protein (and other iron superoxide dismutases). Furthermore the primary structure of both the iron and manganese proteins does not appear to have any homology with any other known amino acid sequence.

Amino Acid Sequence↗
PubMedDate not supplied

The primary structure of mitochondrial aspartate aminotransferase from pig heart: peptides obtained by cleavage with pepsin and with Staphylococcus aureus protease.

Results obtained after digestion of mitochondrial aspartate aminotransferase from pig heart with pepsin and with the protease from S. aureus are described. Peptic digestion produced a very complex mixture of peptides, which were purified and analyzed; structural information contained in these peptides covered nearly the entire molecule. Moreover, the lengths of some individual peptides and the peculiar self-overlapping found with families of peptides from adjacent regions were especially useful and interesting. Not all the possible peptides originating after digestion with S. aureus protease were isolated and examined. However, the high specificity of this protease and its usefulness for sequence studies were confirmed. In particular, the S. aureus peptides obtained were important for establishing the amidation state of glutamic acid/glutamine residues.

Amino Acid Sequence↗
PubMedDate not supplied

Purification of a low molecular weight calf pineal peptide controlling DNA transcription in vitro.

A low molecular factor showing high specific activity in the control DNA of transcription in vitro was isolated from aqueous ultrafiltered calf pineal gland extracts. The active factor was purified by means of Gel filtration on Sephadex G-25 and G-10, thin layer chromatography on aluminum sheet cellulose and high performance liquid chromatography using a Supelcosil LC 318 reverse phase column. The purified pineal factor was characterized as a peptide of low molecular weight (of about 1200 Dalton) containing glutamic acid, leucine, glycine, threonine and alanine in their approximate molar ratio, referred to glycine taken as 1: glycine 1, threonine 1, leucine 1, alanine 6, glutamic acid 2. Studies of the aminoacid sequence by N-terminal analysis using the automated Edman degradation procedure, were unsuccessful, suggesting the presence of a blocked NH2 group. The purified peptide appears to be different from peptide factors till now isolated from pineal gland.

Animals↗
PubMedDate not supplied

The primary structure of mitochondrial aspartate aminotransferase from pig heart: peptides obtained by cleavage at basic residues.

Results obtained as part of a study of the primary structure of mitochondrial aspartate aminotransferase from pig heart are described. In particular, the S-aminoethylated protein was digested with trypsin and with the lysine specific protease from A. mellea. In the first case peptides contained 221 out of the total of 401 amino acid residues in the protein were obtained. By contrast the digest with A. mellea protease was not examined exhaustively and six peptides containing 49 amino acid residues were isolated. Digestion of the trifluoroacetylated and S-aminoethylated protein with A. mellea protease yielded a mixture of large fragments three of which, containing 89 amino acid residues, are described here. The combined results of these three digests yielded 66.6% of the total structure, concentrated mainly in the N-terminal half of the protein.

Amino Acid Sequence↗
PubMedDate not supplied

The primary structure of mitochondrial aspartate aminotransferase from pig heart: peptides obtained by cleavage with thermolysin and chymotrypsin.

The production, purification and analysis of peptide derived by digestion of mitochondrial aspartate aminotransferase with thermolysin and chymotrypsin are described. Despite the complexity of the peptide mixture obtained and the relative shortness of the fragments produced, these digests proved to be very useful for the completion of the primary structure determination of the enzyme. In fact, information for 87% of the total structure was contributed by thermolytic peptides, and for 89% by the chymotryptic ones. Moreover some of these peptides were essential for elucidating controversial points of the sequence.

Amino Acid Sequence↗
PubMedDate not supplied

The primary structure of human erythrocyte copper/zinc superoxide dismutase: cleavage with Staphylococcus aureus protease, determination of the N-terminal blocking group and location of the disulfide bond.

Results obtained after digestion of copper/zinc superoxide dismutase from human erythrocytes with S. aureus protease are described. In particular, peptides soluble in alkaline conditions proved essential for completing the determination of the primary structure of the enzyme; other peptides were important for establishing the amidation state of dicarboxylic amino acid residues and for confirming controversial sequences. The human enzyme is acetylated at the NH2 terminus and contains an intrasubunit disulfide bond connecting half-cystine residues 57 and 146.

Amino Acid Sequence↗