scholarly journals Multimolecular Salivary Mucin Complex Is Altered in Saliva of Cigarette Smokers: Detection of Disulfide Bridges by Raman Spectroscopy

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
Motoe Taniguchi ◽  
Junko Iizuka ◽  
Yukari Murata ◽  
Yumi Ito ◽  
Mariko Iwamiya ◽  
...  
Keyword(s):  
Disulfide Bonds ◽  
Raman Microspectroscopy ◽  
Confocal Laser ◽  
Oral Epithelium ◽  
Amino Acid Residues ◽  
Disulfide Bridges ◽  
Cigarette Smokers ◽  
Laser Raman ◽  
Salivary Mucin ◽  
Premenopausal Female

Saliva contains mucins, which protect epithelial cells. We showed a smaller amount of salivary mucin, both MG1 and MG2, in the premenopausal female smokers than in their nonsmoking counterparts. Smokers' MG1, which contains almost 2% cysteine/half cystine in its amino acid residues, turned out to be chemically altered in the nonsmoker’s saliva. The smaller acidic glycoprotein bands were detectable only in smoker’s saliva in the range of 20–25 kDa and at 45 kDa, suggesting that degradation, at least in part, caused the reduction of MG1 mucin. This is in agreement with the previous finding that free radicals in cigarette smoke modify mucins in both sugar and protein moieties. Moreover, proteins such as amylase and albumin are bound to other proteins through disulfide bonds and are identifiable only after reduction with DTT. Confocal laser Raman microspectroscopy identified a disulfide stretch band of significantly stronger intensity per protein in the stimulated saliva of smokers alone. We conclude that the saliva of smokers, especially stimulated saliva, contains significantly more oxidized form of proteins with increased disulfide bridges, that reduces protection for oral epithelium. Raman microspectroscopy can be used for an easy detection of the damaged salivary proteins.

scholarly journals Stabilization of phage T4 lysozyme by engineered disulfide bonds

1989 ◽  
Vol 86 (17) ◽  
pp. 6562-6566 ◽  
Author(s):  
M Matsumura ◽  
W J Becktel ◽  
M Levitt ◽  
B W Matthews
Keyword(s):  
Disulfide Bonds ◽  
Theoretical Calculations ◽  
Equilibrium Constants ◽  
T4 Lysozyme ◽  
Disulfide Bridges ◽  
Large Loop ◽  
Phage T4 ◽  
Flexible Part ◽  
Free Phage

Four different disulfide bridges (linking positions 9-164, 21-142, 90-122, and 127-154) were introduced into a cysteine-free phage T4 lysozyme at sites suggested by theoretical calculations and computer modeling. The new cysteines spontaneously formed disulfide bonds on exposure to air in vitro. In all cases the oxidized (crosslinked) lysozyme was more stable than the corresponding reduced (noncrosslinked) enzyme toward thermal denaturation. Relative to wild-type lysozyme, the melting temperatures of the 9-164 and 21-142 disulfide mutants were increased by 6.4 degrees C and 11.0 degrees C, whereas the other two mutants were either less stable or equally stable. Measurement of the equilibrium constants for the reduction of the engineered disulfide bonds by dithiothreitol indicates that the less thermostable mutants tend to have a less favorable crosslink in the native structure. The two disulfide bridges that are most effective in increasing the stability of T4 lysozyme have, in common, a large loop size and a location that includes a flexible part of the molecule. The results suggest that stabilization due to the effect of the crosslink on the entropy of the unfolded polypeptide is offset by the strain energy associated with formation of the disulfide bond in the folded protein. The design of disulfide bridges is discussed in terms of protein flexibility.

scholarly journals Plant purple acid phosphatases - genes, structures and biological function.

2003 ◽  
Vol 50 (4) ◽  
pp. 1245-1256 ◽  
Author(s):  
Mariusz Olczak ◽  
Bronisława Morawiecka ◽  
Wiesław Watorek
Keyword(s):  
Disulfide Bridge ◽  
Acid Phosphatases ◽  
Amino Acid Residues ◽  
Disulfide Bridges ◽  
Inorganic Pyrophosphate ◽  
Manganese Ion ◽  
Substrate Preferences ◽  
Purple Acid Phosphatases ◽  
Single Polypeptide ◽  
Monomeric Proteins

The properties of plant purple acid phosphatases (PAPs), metallophosphoesterases present in some bacteria, plants and animals are reviewed. All members of this group contain a characteristic set of seven amino-acid residues involved in metal ligation. Animal PAPs contain a binuclear metallic center composed of two irons, whereas in plant PAPs one iron ion is joined by zinc or manganese ion. Among plant PAPs two groups can be distinguished: small PAPs, monomeric proteins with molecular mass around 35 kDa, structurally close to mammalian PAPs, and large PAPs, homodimeric proteins with a single polypeptide of about 55 kDa. Large plant PAPs exhibit two types of structural organization. One type comprises enzymes with subunits bound by a disulfide bridge formed by cysteines located in the C-terminal region around position 350. In the second type no cysteines are located in this position and no disulfide bridges are formed between subunits. Differences in structural organisation are reflected in substrate preferences. Recent data reveal in plants the occurrence of metallophosphoesterases structurally different from small or large PAPs but with metal-ligating sequences characteristic for PAPs and expressing pronounced specificity towards phytate or diphosphate nucleosides and inorganic pyrophosphate.

scholarly journals Sindbis Virus Glycoprotein E1 Is Divided into Two Discrete Domains at Amino Acid 129 by Disulfide Bridge Connections

2000 ◽  
Vol 74 (19) ◽  
pp. 9313-9316 ◽  
Author(s):  
Brett S. Phinney ◽  
Dennis T. Brown
Keyword(s):  
Amino Acid ◽  
Disulfide Bonds ◽  
Sindbis Virus ◽  
Disulfide Bridge ◽  
Membrane Glycoprotein ◽  
Disulfide Bridges ◽  
Functional Regions ◽  
E1 Protein ◽  
Disulfide Linkages ◽  
Discrete Domains

ABSTRACT The E1 membrane glycoprotein of Sindbis virus contains structural and functional domains, which are conformationally dependent on the presence of intramolecular disulfide bridges (B. A. Abell and D. T. Brown, J. Virol. 67:5496–5501, 1993; R. P. Anthony, A. M. Paredes, and D. T. Brown, Virology 190:330–336, 1992). We have examined the disulfide bonds in E1 and have determined that the E1 membrane glycoprotein contains two separate sets of interconnecting disulfide linkages, which divide the protein into two domains at amino acid 129. These separate sets of disulfides may stabilize and define the structural and functional regions of the E1 protein.

scholarly journals The Primary Structure of Antithrombin-III

1977 ◽  
Author(s):  
T. E. Petersen ◽  
G. Dudek-Wojciechowska ◽  
L. Sottrup-Jensen ◽  
S. Magnusson
Keyword(s):  
Amino Acid ◽  
Antithrombin Iii ◽  
Factor Xa ◽  
Amino Acid Residues ◽  
Disulfide Bridges ◽  
Single Chain ◽  
Terminal Sequence ◽  
Chymotryptic Peptide ◽  
Sequence Region ◽  
Bovine Factor

Human antithrombin-III is a single-chain glycoprotein with three disulfide bridges and four prosthetic glucosamine-based oligosaccharide groups. The disulfide bridges have been established. In four fragments of 208, 168, 3 and 46 amino acid residues, resp. 415 of the appr. 425 residues have been sequenced. The four oligosaccharide groups are attached to four Asn-residues within a sequence region of 95 residues. No extensive sequence homology with the trypsin inhibitors has been observed. One chymotryptic peptide was found to be a substrate for bovine factor Xa, cleaving the arginyl bond in the sequence -Ile-Val-Ala-Glu-Gly-Arg-Asp-. A second peptide is cleaved by thrombin. It is not clear whether these sites are inhibitor sites in the native molecule. Other possible candidates for inhibitor sites are a -Val-Leu-Ile-Leu-Pro-Lys-Pro- sequence (similar to the sequence 40-48 of hirudin, which also includes a -Pro-Lys-Pro- sequence) and also the C-terminal sequence -Gly-Arg-Val-Ala-Asn-Pro-Cys-Val-Lys.

Application of confocal laser Raman spectroscopy on marine sediment microplastics

2020 ◽  
Vol 38 (5) ◽  
pp. 1502-1516
Author(s):  
Jing Liu ◽  
Xin Zhang ◽  
Zengfeng Du ◽  
Zhendong Luan ◽  
Lianfu Li ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Marine Sediment ◽  
Laser Raman Spectroscopy ◽  
Confocal Laser ◽  
Laser Raman

scholarly journals Isolation of insoluble secretory product from bovine thyroid: extracellular storage of thyroglobulin in covalently cross-linked form.

1992 ◽  
Vol 118 (5) ◽  
pp. 1071-1083 ◽  
Author(s):  
V Herzog ◽  
U Berndorfer ◽  
Y Saber
Keyword(s):  
Disulfide Bonds ◽  
Plasma Membranes ◽  
Matrix Protein ◽  
Thyroid Tissue ◽  
Surface Pattern ◽  
Secretory Product ◽  
Disulfide Bridges ◽  
Luminal Content ◽  
Bovine Thyroid ◽  
A Minor

Extracellular storage of thyroglobulin (TG) is an important prerequisite for maintaining constant levels of thyroid hormones in vertebrates. Storage of large amounts is made possible by compactation of TG in the follicle lumen with concentrations of at least 100-400 mg/ml. We recently observed that the luminal content from bovine thyroids can be isolated in an intact state and be separated from soluble TG. For this purpose, bovine thyroid tissue was homogenized and subjected to various steps of purification. This procedure resulted in a pellet of single globules measuring 20-120 microns in diameter. Scanning electron microscopy revealed a unique cobblestone-like surface pattern of isolated globules, showing in detail the impressions of the apical plasma membranes of thyrocytes which had formerly surrounded the luminal content before tissue homogenization. Isolated thyroid globules were rapidly digested by trypsin but extremely resistant to various protein solubilization procedures. Homogenization of isolated globules resulted in the release of approximately 3% of total protein, showing that only a minor proportion of TG was loosely incorporated in thyroid globules whereas approximately 22% appeared to be interconnected with the globule matrix by disulfide bridges. Analysis by SDS-gel electrophoresis and immunoblotting confirmed that the protein released by this procedure consisted of TG. The vast majority (approximately 75%) of the globule matrix protein was found to be covalently cross-linked by non-disulfide bonds. TG in isolated globules was highly iodinated (approximately 55 iodine atoms per 12-S TG subunit) suggesting that the covalent nondisulfide cross-linking occurs in part during the iodination of TG and that this process involves the formation of intermolecular dityrosine bridges. Mechanisms must exist which solubilize or disperse the insoluble luminal content prior to endocytosis of TG.

Lachesana tarabaevi, an expert in membrane-active toxins

2016 ◽  
Vol 473 (16) ◽  
pp. 2495-2506 ◽  
Author(s):  
Alexey I. Kuzmenkov ◽  
Maria Y. Sachkova ◽  
Sergey I. Kovalchuk ◽  
Eugene V. Grishin ◽  
Alexander A. Vassilevski
Keyword(s):  
Amino Acid ◽  
Cleavage Sites ◽  
Amino Acid Residues ◽  
Disulfide Bridges ◽  
Venom Protein ◽  
Active Peptides ◽  
Amphiphilic Molecules ◽  
Helical Wheel ◽  
Membrane Active Peptides ◽  
Covalently Linked

In the present study, we show that venom of the ant spider Lachesana tarabaevi is unique in terms of molecular composition and toxicity. Whereas venom of most spiders studied is rich in disulfide-containing neurotoxic peptides, L. tarabaevi relies on the production of linear (no disulfide bridges) cytolytic polypeptides. We performed full-scale peptidomic examination of L. tarabaevi venom supported by cDNA library analysis. As a result, we identified several dozen components, and a majority (∼80% of total venom protein) exhibited membrane-active properties. In total, 33 membrane-interacting polypeptides (length of 18–79 amino acid residues) comprise five major groups: repetitive polypeptide elements (Rpe), latarcins (Ltc), met-lysines (MLys), cyto-insectotoxins (CIT) and latartoxins (LtTx). Rpe are short (18 residues) amphiphilic molecules that are encoded by the same genes as antimicrobial peptides Ltc 4a and 4b. Isolation of Rpe confirms the validity of the iPQM (inverted processing quadruplet motif) proposed to mark the cleavage sites in spider toxin precursors that are processed into several mature chains. MLys (51 residues) present ‘idealized’ amphiphilicity when modelled in a helical wheel projection with sharply demarcated sectors of hydrophobic, cationic and anionic residues. Four families of CIT (61–79 residues) are the primary weapon of the spider, accounting for its venom toxicity. Toxins from the CIT 1 and 2 families have a modular structure consisting of two shorter Ltc-like peptides. We demonstrate that in CIT 1a, these two parts act in synergy when they are covalently linked. This finding supports the assumption that CIT have evolved through the joining of two shorter membrane-active peptides into one larger molecule.

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