scholarly journals Evaluation of benzofuroxan as a chromophoric oxidizing agent for thiol groups by using its reactions with papain, ficin, bromelain and low-molecular-weight thiols

1977 ◽  
Vol 161 (3) ◽  
pp. 627-637 ◽  
Author(s):  
M Shipton ◽  
T Stuchbury ◽  
K Brocklehurst
Keyword(s):  
Molecular Weight ◽  
Base Catalysis ◽  
Isosbestic Point ◽  
Low Molecular Weight ◽  
Oxidizing Agent ◽  
Thiol Groups ◽  
Acid Attack ◽  
Active Centre ◽  
Thiol Compounds ◽  
Steric Factors

1. Benzofuroxan (benzofurazan 1-oxide, benzo-2-oxa-1,3-diazole N-oxide) was evaluated as a specific chromophoric oxidizing agent for thiol groups. 2. Aliphatic thiol groups both in low-molecular-weight molecules and in the enzymes papain (EC 3.4.22.2), ficin (EC 3.4.22.3) and bromelain (EC 3.4.22.4) readily reduce benzofuroxan to o-benzoquinone dixime; potential competing reactions of amino groups are negligibly slow. 3. The fate of the thiol depends on its structure: a mechanism is proposed in which the thiol and benzofuroxan form an adduct which, if steric factors permit, reacts with another molecule of thiol to form a disulphide; when the thiol is located in the active site of a thiol proteinase and steric factors preclude enzyme dinner formation, the adduct reacts instead with water or HO- to form a sulphenic acid; attack on the sulphur atom of the adduct by either a sulphur or oxygen nucleophile releases o-benzoquinone dioxine. 4. Benzofuroxan contains n o proton-binding sites with pKa values in the range 3-10 and probably none in the range 0-14; o-benzoquinone dioxine undergoes a one-proton ionization with pKa=6.75.5. o-benzoquinone dioxime absorbs strongly at wavelengths greater than 410nm, where absorption by benzofuroxan, proteins and simple thiol compounds is negligible; 416 nm is an isosbestic point (epsilon 416 = 5110 litre. mol-1-cm-1); epsilon430=3740+[1460/(1+[H+]/Ka)] where pKa=6.75. 6. The possibility of acid-base catalysis of the oxidation by active-centre histidine residues of the thiol proteinases is discussed.

scholarly journals Thiol-Modification as Important Mode of Action for Allicin from Garlic (Allium sativum)

Proceedings ◽  
2019 ◽  
Vol 11 (1) ◽  
pp. 27 ◽  
Author(s):  
Martin C. H. Gruhlke
Keyword(s):  
Molecular Weight ◽  
Biological Activity ◽  
Active Compound ◽  
Mode Of Action ◽  
Allium Sativum ◽  
Cysteine Residues ◽  
Low Molecular Weight ◽  
Thiol Groups ◽  
Ancient Times ◽  
In Cells

Garlic is a common ingredient in food, normally used as spice but is also used since ancient times for its health beneficial activity. The thiosulfinate allicin is the first active compound in freshly damaged garlic tissue and reacts with thiol-groups. Hence, allicin is able to modify thiol groups, both of protein cysteine-residues and low-molecular weight thiols like glutathione. This thiol-modification is supposed to be an important mechanism for allicin’s biological activity. Here, the mechanisms and possible targets for allicin in cells are discussed.

scholarly journals Glucose- and phlorrhizin-protected thiol groups in pig intestinal brush-border membranes.

1975 ◽  
Vol 147 (3) ◽  
pp. 617-619 ◽  
Author(s):  
M W Smith ◽  
D R Ferguson ◽  
K A Burton
Keyword(s):  
Molecular Weight ◽  
Polyacrylamide Gel Electrophoresis ◽  
Biological Response ◽  
Low Molecular Weight ◽  
Thiol Groups ◽  
Intestinal Brush Border ◽  
Brush Borders ◽  
Weight Protein ◽  
Labelled Compound ◽  
Low Molecular Weight Protein

Purified brush borders, prepared fro newborn pig intestine, were incubated in the presence of 203Hg-labelled p-chloromercuribenzenesulphonic acid and the membrane proteins later separated by polyacrylamide-gel electrophoresis. The presence of either D-glucose or phlorrhizin, during a preliminary incubation in non-radioactive p-chloromercuribenzenesulphonic acid, increased the subsequent binding of the 203Hg-labelled compound to a protein of molecular weight 31500. This increase appeared to be specific for the low-molecular-weight protein, provided that the concentration of protecting agent used corresponded to that used to produce a biological response in the intact tissue. These results are discussed in relation to the known properties of other presumptive sugar carriers isolated from different membranes.

Sulphydryl Oxidation in the Mechanism of Molecular-Weight Conversion of Renin in Dog Kidney

1982 ◽  
Vol 62 (2) ◽  
pp. 157-162 ◽  
Author(s):  
Fumihiko Ikemoto ◽  
Kazuo Takaori ◽  
Hiroshi Iwao ◽  
Kenjiro Yamamoto
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Renal Cortex ◽  
Soluble Fraction ◽  
Low Molecular Weight ◽  
Oxidizing Agent ◽  
Nitrobenzoic Acid ◽  
Binding Substance ◽  
Sh Group ◽  
Dog Kidney

1. A high-molecular-weight renin (Mr 60 000) was formed by the reaction of a low-molecular-weight renin (Mr 40 000) with a renin-binding substance in canine renal cortical extract in the presence of the sulphydryl (SH) group oxidizing agent potassium tetrathionate; thus the reaction required SH oxidation. 2. Renin extracted from isolated renin granules was adsorbed on to thiopropyl Sepharose 6B, and then liberated with dithiothreitol (50 mmol/l), indicating that it possessed on SH moiety(s). 3. However, the renin was capable of reaction with the renin-binding substance even after its SH moiety (or moieties) was protected with 5,5′-dithiobis-(2-nitrobenzoic acid). 4. The high-molecular-weight renin was converted into the low-molecular-weight renin by incubation (37°C, 15 min) with cytosol (soluble fraction) of renal cortex and liver. Such converting ability was diminished after the cytosol was treated with perchloric acid or potassium tetrathionate. 5. These results suggest that the reaction of renin with the renin-binding substance does not require disulphide bond(s) and that an enzymelike substance which is sensitive to SH oxidation is involved in the conversion from the high-molecular-weight renin into the low-molecular weight renin.

scholarly journals Chemical cytometry of thiols using capillary zone electrophoresis-laser induced fluorescence and TMPAB-o-M, an improved fluorogenic reagent

The Analyst ◽  
2016 ◽  
Vol 141 (4) ◽  
pp. 1325-1330 ◽  
Author(s):  
Xiao-Feng Guo ◽  
Jennifer Arceo ◽  
Bonnie Jaskowski Huge ◽  
Katelyn R. Ludwig ◽  
Norman J. Dovichi
Keyword(s):  
Molecular Weight ◽  
Capillary Zone Electrophoresis ◽  
Laser Induced Fluorescence ◽  
Low Molecular Weight ◽  
Thiol Compounds ◽  
Physiological Processes ◽  
Chemical Cytometry ◽  
Zone Electrophoresis ◽  
Capillary Zone

Low molecular weight thiol compounds play crucial roles in many physiological processes.

scholarly journals Low-Molecular-Weight Thiols and Thioredoxins Are Important Players in Hg(II) Resistance in Thermus thermophilus HB27

2017 ◽  
Vol 84 (2) ◽  
Author(s):  
J. Norambuena ◽  
Y. Wang ◽  
T. Hanson ◽  
J. M. Boyd ◽  
T. Barkay
Keyword(s):  
Heavy Metals ◽  
Molecular Weight ◽  
Thermus Thermophilus ◽  
Mercury Resistance ◽  
Low Molecular Weight ◽  
Thiol Groups ◽  
Content Type ◽  
Protein Thiols ◽  
Thioredoxin System

ABSTRACTMercury (Hg), one of the most toxic and widely distributed heavy metals, has a high affinity for thiol groups. Thiol groups reduce and sequester Hg. Therefore, low-molecular-weight (LMW) and protein thiols may be important cell components used in Hg resistance. To date, the role of low-molecular-weight thiols in Hg detoxification remains understudied. The mercury resistance (mer) operon ofThermus thermophilussuggests an evolutionary link between Hg(II) resistance and low-molecular-weight thiol metabolism. Themeroperon encodes an enzyme involved in methionine biosynthesis, Oah. Challenge with Hg(II) resulted in increased expression of genes involved in the biosynthesis of multiple low-molecular-weight thiols (cysteine, homocysteine, and bacillithiol), as well as the thioredoxin system. Phenotypic analysis of gene replacement mutants indicated that Oah contributes to Hg resistance under sulfur-limiting conditions, and strains lacking bacillithiol and/or thioredoxins are more sensitive to Hg(II) than the wild type. Growth in the presence of either a thiol-oxidizing agent or a thiol-alkylating agent increased sensitivity to Hg(II). Furthermore, exposure to 3 μM Hg(II) consumed all intracellular reduced bacillithiol and cysteine. Database searches indicate thatoah2is present in allThermussp.meroperons. The presence of a thiol-related gene was also detected in some alphaproteobacterialmeroperons, in which a glutathione reductase gene was present, supporting the role of thiols in Hg(II) detoxification. These results have led to a working model in which LMW thiols act as Hg(II)-buffering agents while Hg is reduced by MerA.IMPORTANCEThe survival of microorganisms in the presence of toxic metals is central to life's sustainability. The affinity of thiol groups for toxic heavy metals drives microbe-metal interactions and modulates metal toxicity. Mercury detoxification (mer) genes likely originated early in microbial evolution in geothermal environments. Little is known about howmersystems interact with cellular thiol systems.Thermusspp. possess a simplemeroperon in which a low-molecular-weight thiol biosynthesis gene is present, along withmerRandmerA. In this study, we present experimental evidence for the role of thiol systems in mercury resistance. Our data suggest that, inT. thermophilus, thiolated compounds may function side by side withmergenes to detoxify mercury. Thus, thiol systems function in consort withmer-mediated resistance to mercury, suggesting exciting new questions for future research.

scholarly journals Isolation and analysis of a non-protein low molecular weight thiol-mercurial adduct from human prostate lymph node cells (LNCaP)

2020 ◽  
Vol 40 (6) ◽  
Author(s):  
Michael Gronow
Keyword(s):  
Molecular Weight ◽  
Low Molecular Weight ◽  
Anion Exchange Column ◽  
Thiol Compounds ◽  
New Class ◽  
Prostate Cells ◽  
Intermediate Fraction ◽  
Lymph Node Cells ◽  
Protein Matrices ◽  
Malignant Prostate

Abstract Thiol compounds present in human malignant prostate cells (LNCaP) were investigated after reaction with a mercurial blocking reagent. After extracting the cellular glutathione and some other low molecular weight (LMW) thiols using trichloroacetic acid the resulting the protein precipitate was extracted with buffered 8 M urea containing 2-chloromercuri-4-nitrophenol in an equimolar amount to that of the thiol present. After removing the insoluble chromatin fraction the urea soluble labeled adducts formed were chromatographed on G15 Sephadex. Three yellow coloured (A410 nm) fractions were obtained; first, the excluded protein fraction containing 16.0 ± 4.1% of the applied label followed by an intermediate fraction containing 5.9 ± 1.2%. Finally a LMW fraction emerged which contained 77.2 ± 3.7% of the total label applied and this was further analyzed by column chromatography, first on an anion exchange column and then on a PhenylSepharose 6 column to give what appeared to be a single component. LC–MS analysis of this component gave a pattern of mercuri-clusters, formed on MS ionization showing possible parent ions at 704 or 588 m/z, the former indicating that a thiol fragment of molecular weight approximately 467 could be present. No fragments with a single sulfur adduct (a 369 m/z fragment) were observed The adduct was analyzed for cysteine and other amino acids, nucleic acid bases, ribose and deoxyribose sugars, selenium and phosphorus; all were negative leading to the conclusion that a new class of unknown LMW thiol is present concealed in the protein matrices of these cells.

scholarly journals The formation of exchangeable sulphite from adenosine 3′-phosphate 5′-sulphatophosphate in yeast

1976 ◽  
Vol 158 (2) ◽  
pp. 255-270 ◽  
Author(s):  
L G Wilson ◽  
D Bierer
Keyword(s):  
Molecular Weight ◽  
Freeze Drying ◽  
Enzyme Reaction ◽  
Paper Electrophoresis ◽  
Sulphate Reduction ◽  
Low Molecular Weight ◽  
Thiol Groups ◽  
Reaction Systems

A new low-molecular-weight bound sulphite was found in yeast enzyme reaction systems which convert the sulphur of 35S-labelled adenosine 3′-phosphate 5′-sulphatophosphate into exchangeable radioactive sulphite. This bound sulphite was separated from other components by paper electrophoresis and Sephadex G-25 chromatography, and shown to be a peptide with multiple thiol groups and an estimated mol.wt. of 1400. The labelled sulphur in this peptide is highly exchangeable with unlabelled sulphite, but exchangeability decreases with time and freeze-drying. The low-molecular-weight acceptor is tightly bound to enzyme B of the yeast system and, apparently, accepts the sulpho group of adenosine 3′-phosphate 5′-sulphatophosphate and is released as bound sulphite only in the presence of enzymically or chemically reduced fraction C. It is proposed that the low-molecular-weight acceptor is a carrier peptide which, after release of the reduced sulphur, becomes re-oxidized and returns to enzyme B. Fraction C appears to function as an obligatory reductant of the oxidized acceptor before it can accept another-SO-3-moiety from adenosine 3′-phosphate 5′-sulphatophosphate. These findings are consistent with mechanisms proposed for sulphate reduction in spinach and Chlorella, and suggest that fraction C is the natural thiol required in these systems. An improved column technique for the preparation of adenosine 3′-phosphate 5′-sulphatophosphate is described.

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