The disulphide bridges of bovine chymotrypsinogen B.
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ABSTRACT:
SUBMITTER: Smillie LB
PROVIDER: S-EPMC1198434 | biostudies-other | 1967 Dec
REPOSITORIES: biostudies-other
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Project description:1. A new method is described for ;fingerprinting' cysteic acid peptides derived from the disulphide bridges of proteins. Cystine peptides are separated by paper electrophoresis and oxidized on paper by performic acid vapour. Electrophoresis at right angles to the first direction produces parallel groups of cysteic acid peptides lying off a diagonal. This ;fingerprint' reveals the way in which the cysteic acid peptides were originally joined in the protein. 2. The method allows a very easy selective purification of cysteic acid peptides. 3. By applying this method to bovine chymotrypsinogen A, we found that the half-cystine residues were linked 1-122, 42-58, 136-201, 168-182 and 191-220.
| S-EPMC1270086 | biostudies-other
Project description:Evidence is presented for the disulphide bridges in bovine Factor X. The protein was degraded by chemical and enzymic means, and all 12 disulphide bridges were isolated in separate peptides except for bridges nos. 6/7 in the light chain. All the disulphide bridges were found to be in positions corresponding to those found in other homologous domains. This report is the first verification of an epidermal-growth-factor-homologous domain having the same disulphide-bonding pattern as that found in mouse epidermal growth factor.
| S-EPMC1148212 | biostudies-other
Project description:BACKGROUND: Phospholipase C (PLC) is an enzyme that plays pivotal role in a number of signaling cascades. These are active in the plasma membrane and triggers cellular responses by catalyzing the hydrolysis of membrane phospholipids and thereby generating the secondary messengers. Phosphatidylinositol-PLC (PI-PLC) specifically interacts with phosphoinositide and/or phosphoinositol and catalyzes specific cleavage of sn-3- phosphodiester bond. Several isoforms of PLC are known to form and function as dimer but very little is known about the molecular basis of the dimerization and its importance in the lipid interaction. PRINCIPAL FINDINGS: We herein report that, the disruption of disulphide bond of a novel PI-specific PLC of C. reinhardtii (CrPLC) can modulate its interaction affinity with a set of phospholipids and also the stability of its dimer. CrPLC was found to form a mixture of higher oligomeric states with monomer and dimer as major species. Dimer adduct of CrPLC disappeared in the presence of DTT, which suggested the involvement of disulphide bond(s) in CrPLC oligomerization. Dimer-monomer equilibrium studies with the isolated fractions of CrPLC monomer and dimer supported the involvement of covalent forces in the dimerization of CrPLC. A disulphide bridge was found to be responsible for the dimerization and Cys7 seems to be involved in the formation of the disulphide bond. This crucial disulphide bond also modulated the lipid affinity of CrPLC. Oligomers of CrPLC were also captured in in vivo condition. CrPLC was mainly found to be localized in the plasma membrane of the cell. The cell surface localization of CrPLC may have significant implication in the downstream regulatory function of CrPLC. SIGNIFICANCE: This study helps in establishing the role of CrPLC (or similar proteins) in the quaternary structure of the molecule its affinities during lipid interactions.
| S-EPMC3380823 | biostudies-literature
Project description:The arrangement of the disulphide bridges of the major component of the light chains of immunoglobulins (kappa-chains) has been studied in the Bence-Jones proteins. Three disulphide bridges have been found. An interchain bridge at the C-terminus has been shown to occur in the dimers of all the proteins studied and was characterized by symmetrical peptides. In the monomer form, the C-terminal half-cystine of the corresponding peptides was linked to a lone half-cystine residue. A second common disulphide-bridge peptide in which a single amino acid difference could be related to the Inv factors of the individual proteins was found in Bence-Jones proteins and in the kappa-chains of normal and abnormal immunoglobulins. Peptides characteristic of a third disulphide bridge studied in three specimens were found to have differences in some residues, but also striking similarities. A methionine peptide has also been characterized in two specimens as a by-product of the technique employed. It is suggested that a general manner of folding may be a common feature of the heterogeneous population of kappa-chains: one bridge which folds an invariable stretch of the chain, another bridge which folds a stretch that varies from protein to protein, and a bridge at the C-terminus which is the interchain link.
| S-EPMC1270114 | biostudies-other
Project description:Mouse IgM (immunoglobulin M) was selectively and partially reduced and treated with iodo[2-14C]acetate to label the interchain disulphide bridges. The carboxymethylation was studied in some detail. The labelled peptides were purified, sequenced and positioned by homology with human IgM. Only peptides originating from three interchain disulphide bridges were labelled, in contrast with the four labelled bridges obtained in human IgM under the same conditions. These peptides are homologous to human bridge peptides forming the heavy-light bridge and two inter-heavy bridges, one present in the CMU2 region and the other in the C-terminal region. The inter-heavy bridge in the Cmu2 region was alone cleaved and radioactively labelled in selectively reduced IgM held together as a pentamer by non-covalen interactions. The same bridge was the only one to be totally cleaved in subunits released after more extensive, though still selective, reduction. In the light of these results a possible arrangement of the disulphide bridges of the mouse IgM.
| S-EPMC1172409 | biostudies-other
Project description:Schistosome helminths constitute a major health risk for the human population in many tropical areas. We demonstrate for the first time that several developmental stages of the human parasite Schistosoma mansoni express arginase, which is responsible for the hydrolysis of l-arginine to l-ornithine and urea. Arginase activity by alternatively activated macrophages is an essential component of the mammalian host response in schistosomiasis. However, it has not been previously shown that the parasite also expresses arginase when it is in contact with the mammalian host. After cloning and sequencing the cDNA encoding the parasite enzyme, we found that many structural features of human arginase are well conserved in the parasite ortholog. Subsequently, we discovered that S. mansoni arginase shares many similar molecular, biochemical and functional properties with both human arginase isoforms. Nevertheless, our data also reveal striking differences between human and schistosome arginase. Particularly, we found evidence that schistosome arginase activity depends upon disulphide bonds by cysteines, in contrast to human arginase. In conclusion, we report that S. mansoni arginase is well adapted to the physiological conditions that exist in the human host.
| S-EPMC2756234 | biostudies-literature
Project description:As a novel alternative to established surface display or combinatorial chemistry approaches for the discovery of therapeutic peptides, we present a method for the isolation of small, cysteine-rich domains from bovine antibody ultralong complementarity-determining regions (CDRs). We show for the first time that isolated bovine antibody knob domains can function as autonomous entities by binding antigen outside the confines of the antibody scaffold. This yields antibody fragments so small as to be considered peptides, each stabilised by an intricate, bespoke arrangement of disulphide bonds. For drug discovery, cow immunisations harness the immune system to generate knob domains with affinities in the picomolar to low nanomolar range, orders of magnitude higher than unoptimized peptides from naïve library screening. Using this approach, knob domain peptides that tightly bound Complement component C5 were obtained, at scale, using conventional antibody discovery and peptide purification techniques.
| S-EPMC7498065 | biostudies-literature
Project description:[(35)S]Cystine-labelled immunoglobulin MOPC21 (IgG1) was prepared from myeloma cells in tissue culture. Carrier myeloma protein was added and the protein was digested with pepsin. The digest was fractionated on Sephadex G-50 into two fractions, further digested with trypsin and again fractionated on Sephadex. Disulphide-bridge peptides were purified by electrophoresis and chromatography and identified by radioautography. A peptide of 96 residues was isolated, which contains both the heavy-light interchain disulphide bridge and all the inter-heavy-chain disulphide bridges. Other peptides were isolated, accounting for all the intrachain disulphide bridges (which could be placed by homology with proteins of other species), except for the variable section of the light chain. Sequences describing this missing disulphide bridge were obtained from totally reduced and alkylated light chains. Peptides related to the interchain disulphide-bridge peptide were isolated from partially reduced and alkylated myeloma protein and from totally reduced heavy chain. The interchain disulphide-bridge peptide was placed at the C-terminal position of the F(ab')(2) fragment, prepared by digestion of the protein with pepsin at pH4.0. Sequences from the heavy-chain intrachain disulphide bridges of MOPC 21 immunoglobulin are compared with homologous sequences from mouse myeloma proteins of other subclasses and proteins of other species.
| S-EPMC1178493 | biostudies-other
Project description:The arrangement of the disulphide bridges in human low-Mr kininogen has been elucidated. Low-Mr kininogen contains 18 half-cystine residues forming nine disulphide bridges. The first and the last half-cystine residues of the amino acid sequence form a disulphide loop which spans the heavy- and the light-chain portion of the kininogen molecule. The other 16 half-cystine residues are linked consecutively to form eight loops of 4-20 amino acids; these loops are lined up in the heavy-chain portion of the kininogen molecule. In this way, a particular pattern of disulphide loops is formed which seems to be of critical importance for the inhibitor function of human kininogen.
| S-EPMC1148362 | biostudies-other
Project description:1. Cysteic acid peptides from various digests of calf rennin were purified by diagonal paper electrophoresis. 2. The amino acid sequence of these peptides accounts for 38 amino acids around three unique disulphide bridges in rennin. 3. One bridge connects two acidic regions of the chain, one forms a loop of five residues and the other a loop of six residues. 4. These bridges are homologous with those of hog pepsin. 5. Tryptic peptides from the C-terminus of rennin account for 22 residues, 17 of which are homologous with the C-terminus of pepsin. 6. Altogether, sequences accounting for 94 of the 270 residues in rennin are described and the degree of homology with pepsin approximates to 70%.
| S-EPMC1271253 | biostudies-other