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Biomedical subjects

D Barra

Publications and source records attributed to D Barra.

At least 181 records · Page 10Linked to original sources
PubMed1975

The primary structure of aspartate aminotransferase from pig heart muscle. Digestion with a proteinase having specificity for lysine residues.

Carboxymethylated aspartate aminotransferase was digested with a proteinase claimed to be specific for lysine residues. Complete cleavage occurred at 12 of the 19 lysine residues in the protein, but at the remaining seven residues cleavage was either restricted or absent. In addition, cleavage was observed at three of the 26 arginine residues. These results are discussed with reference to the amino acid residues adjacent to points of complete or restricted cleavage. The complete primary structure of aspartate aminotransferase, based on these and other studies, is given. Evidence for the assignment of some acid and amide side chains has been deposited as Supplementary Publication SUP 50050 (11 pp.) at the British Library (Lending Division), Boston Spa, Wetherby, W. Yorkshire LS23 7BQ, U.K., from whom copies can be obtained on the terms indicated in Biochem. J. (1975) 145, 5. The evidence for the assignment of residue 366 was less conclusive than for the other acid and amide side chains and is, therefore, given in the main paper.

Amino Acid Sequence↗
PubMed1973

The primary structure of aspartate aminotransferase from pig heart muscle. Partial sequences determined by digestion with thermolysin and elastase.

Peptides produced by thermolytic digestion of aminoethylated aspartate aminotransferase and of the oxidized enzyme were isolated and their amino acid sequences determined. Digestion by elastase of the carboxymethylated enzyme gave peptides representing approximately 40% of the primary structure. Fragments from these digests overlapped with previously reported sequences of peptides obtained by peptic and tryptic digestion (Doonan et al., 1972), giving ten composite peptides containing 395 amino acid residues. The amino acid composition of these composite peptides agrees well with that of the intact enzyme. Confirmatory results for some of the present data have been deposited as Supplementary Publication 50018 at the National Lending Library for Science and Technology, Boston Spa, Yorks. LS23 7BQ, U.K., from whom copies can be obtained on the terms indicated in Biochem. J. (1973) 131, 5.

Amino Acid Sequence↗
PubMed1972

The primary structure of aspartate aminotransferase from pig heart muscle. Partial sequences determined by digestion with pepsin and trypsi trypsin.

Peptides obtained by tryptic digestion of carboxymethylated and maleylated aspartate aminotransferase and of the aminoethylated enzyme were isolated and the complete amino acid sequences of most of them were determined. Digestion of the carboxymethylated protein with pepsin produced a complex mixture of peptides that allowed some overlapping of the tryptic peptides (Fig. 4); in addition, peptides were obtained that had not been found in either of the tryptic digests. From these studies about 400 amino acid residues were identified. Experimental details and confirmatory data for the results presented here are given in a supplementary paper that has been deposited as Supplementary Publication 50011 at the National Lending Library for Science and Technology, Boston Spa, Yorks. LS23 7BQ, U.K., from whom copies can be obtained on the terms indicated in Biochem. J. (1972) 126, 5.

Alkylation↗
PubMedDate not supplied

Six novel tachykinin- and bombesin-related peptides from the skin of the Australian frog Pseudophryne güntheri.

Six novel peptides belonging to the tachykinin and bombesin families were isolated and sequenced from extracts of the skin of the Australian myobatrachid frog Pseudophryne güntheri. One of these peptides (PG-L) was of the bombesin family and may be considered an N-elongation of the litorin/ranatensin molecule, with which it shares an identical spectrum of activity on isolated smooth muscle preparations. The other five peptides were of the tachykinin family with two of these peptides (PG-SPI and PG-SPII) related to substance P and three (PG-KI, PG-KII and PG-KIII) to kassinin. In contrast to the basic nature of substance P, the PG-SP peptides showed a clear acidic character and displayed a more potent and sustained action on isolated smooth muscle preparations and rat blood pressure than did substance P. Two of the three PG-K peptides were more potent than kassinin; PG-KIII was considerably less potent. PG-KI and PG-KII were also present in a deamidated, poorly active, form.

Amino Acid Sequence↗
PubMedDate not supplied

Bovine pancreatic trypsin inhibitor and homologous polypeptide inhibitors in nephron cells.

Bovine pancreatic trypsin inhibitor (BPTI, aprotinin) is a fifty-eight amino acid polypeptide, which is present together with related molecular isoforms in various bovine organs. In the present study these protease inhibitors were isolated from bovine kidney by affinity chromatography on immobilized trypsin and a subsequent FPLC step. Due to their electrophoretic, structural, and inhibitory properties, the inhibitors were strictly similar to the polypeptides identified previously in other bovine organs. Immunohistochemical experiments showed a widespread localization of these polypeptides in nephron epithelial cells (proximal and distal tubules, loop of Henle, collecting tubules).

Amino Acid Sequence↗