Primary Structure Of Peptide Research Articles

Acid‐base properties for each protonation site of six corticotropin fragments

The individual basicity of each protonation site for six different fragments of aH-ACTH (corticotropin) have been characterized in terms of group constants. Microconstants have also been estimated for the N- and C-terminal moieties of ACTH (15-32) and ACTH (1-28), respectively. In these cases the bifunctional termini contain adjacent protonation sites of similar basicity in close interaction. For fragments consisting of 14 or fewer amino acids the acid-base properties of all the protonation sites can be well interpreted by taking into account only the primary peptide structure. The group constant values for ACTH (15-32), ACTH (1-28) and ACTH (1-32) provide evidence that the functional groups of these fragments are influenced by several intramolecular interactions such as H-bonding and macromolecular hydrophobic effects. By means of the above constants the concentration of any arbitrarily chosen microspecies can be calculated.

Primary structure of peptides from bovine brain glutamine synthetase. Comparison with sequences of glutamine synthetases from other organisms

An analysis of the covalent structure of bovine brain glutamine synthetase has been initiated. Cyanogen bromide and tryptic digests have yielded peptides accounting for most of the polypeptide subunit, and sequence analysis has placed in order over half of the amino acids within these peptides. The amino terminus is acetylated and has the following partial sequence: Ac(H, S 3, A 2 T)-L-B-K-G-I-K-Z-V-Y-M. The carboxyl-terminal sequence is: A-L-P-Q-G-D-K-V-Q-A-M. The peptides isolated from bovine glutamine synthetase show a high degree of homology with peptides isolated from ovine and porcine brain glutamine synthetases. In contrast to the sequence homologies of the proteins from eukaryotic sources, there are no obvious amino acid sequence homologies between bovine brain glutamine synthetase and any prokaryotic glutamine synthetase. Bovine brain glutamine synthetase is inactivated by phenylglyoxal and N-ethylmaleimide. In both cases catalytic activity is protected by the presence of ATP, suggesting the presence of arginine and cysteine residues at or near the ATP binding site.

Computarized Searching Program to Identify the Primary Structure of Peptides and Proteins by Using Chemical Shifts C‐13 Data. Amino Acids

AbstractA computer program to identify the primary structure of “unknown” peptides and proteins is described, based upon the Chemical shifts of C‐13 for 28 common amino acids. The spectra have been measured by high resolution nmr spectroscopy to be used as reference data. To facilitate the investigation procedure, the characteristic Chemical shift (s) are selected. The operation of the program and its performance in investigation of unknown spectra of three hypothetical peptides are fully illustrated after complete hydrolysis in 6N HCl. Correlation between the obtainable results proved the stability of a hydrolysis intermediate by‐product kinetically affected by the polar and steric factors of the main function group in the media.

Human pancreatic icosapeptide: isolation, sequence, and immunocytochemical localization of the COOH-terminal fragment of the pancreatic polypeptide precursor.

In dogs, the COOH-terminal part of the pancreatic polypeptide precursor gives rise to a stable icosapeptide product against which an antiserum has been raised. By immunohistochemistry, icosapeptide immunoreactivity was localized in human pancrease exclusively to cells that also stored pancreatic polypeptide. Analytical peptide chemistry demonstrated that a peptide corresponding to the canine icosapeptide could be extracted from the pancreatic polypeptide-rich duodenal part of the human pancreas. The human pancreatic icosapeptide was isolated by acid ethanol extraction, gel filtration, anion-exchange chromatography, and reverse-phase high-performance liquid chromatography. The COOH-terminal sequence of the human icosapeptide is very similar to that of the canine icosapeptide, whereas none of the first nine amino acid residues are identical. When the primary structure of peptides from three different species are compared, it is apparent that the pancreatic polypeptide part of the common precursor is a well-conserved sequence as compared to the icosapeptide part, although 8 out of 11 residues in the COOH-terminal sequence of the icosapeptide are identical in all three species.

Fractionation of CNBr fragments and primary structures of peptides of the adenovirus hexon protein.

The adenovirus hexon protein has been carboxymethylated with 14C-labeled iodoacetate. After treatment with CNBr, the peptide mixture was fractionated into fragments with seven size classes by exclusion chromatography. Large fragments were further purified by CM-cellulose chromatography in urea, and small fragments were purified by high voltage paper electrophoresis. Amino acid sequences of pure fragments have been determined by combined use of sequenator-based direct degradations, and of manual t-dimethylaminonaphthalene-1-sulfonyl-monitored Edman degradations subsequent to enzymatic redigestions. Fractionations are given, the primary structures of 22 CNBr fragments containing a total of 677 residues are reported, and the analytical aspects of the structural properties are considered.

Chemical structure of peptidoglycan in Selenomonas ruminantium: cadaverine links covalently to the D-glutamic acid residue of peptidoglycan.

The peptidoglycan of Selenomonas ruminantium, a strictly anaerobic bacterium, contains cadaverine (Y. Kamio, Y. Itoh, Y. Terawaki, and T. Kusano, J. Bacteriol. 145:122-128, 1981). This report describes the chemical structure of the peptidoglycan of this bacterium. The [14C]cadaverine-labeled peptidoglycan was degraded with the lytic enzymes prepared from Streptomyces albus G into three small fragments including a major fragment (band A compound). Bank A compound was composed of L-alanine, D-glutamic acid, meso-diaminopimelic acid, D-alanine, and cadaverine in the molar ratio 0.98:1.0:1.0:0.98:0.97. Diaminopimelic acid, L-alanine, and cadaverine were N-terminal residues in band A compound. When the [14C]cadaverine-labeled band A compound was subjected to partial acid hydrolysis, two peptide fragments were obtained. One of them consisted of diaminopimelic acid and D-alanine; diaminopimelic acid was the N-terminal amino acid, and the other fragment was composed of L-alanine, D-glutamic acid, and cadaverine, of which L-alanine and cadaverine were N-terminal. These results lead us to conclude that the primary peptide structure of band A compound is L-alanyl-D-glutamyl-meso-diaminopimelyl-D-alanine and that cadaverine links covalently to the D-glutamic acid residue.

Identification of the amino acid residues of proteins S5 and S8 adjacent to each other in the 30 S ribosomal subunit of Escherichia coli.

When Escherichia coli 30 S ribosomal subunits are reacted with protein-protein bifunctional reagents, a number of protein pairs as well as aggregates containing three or more ribosomal proteins are formed. In the present study we have purified one of the protein pairs obtained by reaction of 30 S ribosomal subunits with either radioactive or nonradioactive dimethylsuberimidate. Following molecular weight determination and ammonolysis, the pair was shown to consist of ribosomal proteins S5 and S8. The "native" structure of the complex was surmised from its capacity to be reconstituted into a biologically active 30 S ribosomal subunit. From peptide maps and primary structure determination of various peptides it was demonstrated that the cross-linking bond between ribosomal proteins S5 and S8 involves primarily the residues Lys-93 of protein S8 and the COOH-terminal lysine (Lys-166) of ribosomal protein S5. This result is substantiated by the finding that a mutant carrying an altered S5 lacking the COOH-terminal lysine yields a greatly reduced amount of S5-S8 cross-link. In addition to the points of cross-linking it was found that Lys-30, Lys-68, and Lys-86 of S8 and Lys-5 of S5 react with dimethylsuberimidate, indicating that these residues are available for reaction and suggesting their topographical localization on the ribosomal surface.

Primary structure of peptides which form the disulfide bonds of chicken pepsin

The molecule of chicken pepsin is cross-linked by three disulfide bonds. The structures of the half-cystine peptides which form these bonds were determined by the analysis of different enzymic digests of the enzyme. The order of the disulfide bonds in the molecule was elucidated with regard to sequential homologies between chicken pepsin and other acid proteases. The three disulfide bonds of chicken pepsin, numbered from the N-terminus of pepsin, are: 1st bond Ile-Tyr-Cys-(Lys-Ser-Ser-Ala)-Cys-Ser-Asn-His-Lys; 2nd bond Val-Ala-Cys-Cys-(Thr-Phe)-Gln-Ala; 3rd bond Asp-Leu-Gly-Val-Ser-Ser-Asp-Gly-Glu-Ile-Ser-Cys-(Asp-Asp-Ile-Ser-Lys-Leu-Pro-Asp)-Cys-(Ser-Gly-Asp-Glu-Asn-Leu-Val)-Met.

Proton magnetic resonance spectroscopic studies using paramagnetics of primary and tertiary structure of proteins

Abstract

Primary structure of peptides released during activation of human plasminogen by urokinase.

Activation of human plasminogen by urokinase is a two‐stage process. Initially peptide material is released from the NH2‐terminal part of the proenzyme during formation of an inactive intermediate compound, from which plasmin is formed in a second step by proteolytic cleavage of an internal peptide bond. The released peptide material is shown to consist of two peptides, API and APII, containing 63 and 5 amino acid residues, respectively. The amino acid sequences of these peptides, and of two cyanogen bromide fragments situated in the NH2‐terminal part of the plasminogen molecule (CNBr II and CNBr III), have been determined. From these results it is shown that API and APII, in intact plasminogen, occupy the positions 1–63 and 64–68 respectively. The residue in position 69 is shown to be methionine, which also is the NH2‐terminal amino acid found in the intermediate compound formed during activation.

Accentuation of interferon production by metabolic inhibitors and its dependence on protein synthesis

We examined the effect of protein inhibitors on interferon production by rabbit kidney cell cultures stimulated with a complexed polyribonucleotide (poly I-poly C). Puromycin and p-fluorophenylalanine, inhibitors which alter primary structure of peptides, inhibited interferon production. Cycloheximide and emitine, which retard elongation of nascent peptides, inhibited interferon production at high doses but for each inhibitor a dose range was found that would accentuate interferon production. Interferon production in the presence of accentuating concentrations of cycloheximide and emetine could be inhibited by puromyein. After treatment with actinomycin D, interferon production is dose-responsively inhibited by cycloheximide. We explain these results in terms of the modes of action of the inhibitors and their effect on a hypothetical labile regulatory protein which is involved in shutting off interferon production. We conclude that interferon production requires new protein synthesis in this system.