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PubMed1988

Modulation of cellular transglutaminase: protease-induced activation.

Multiple molecular forms of transglutaminase are found in cells and each form is widely distributed. We find a 95 K dalton enzyme associated with membrane fractions. A 50 K dalton enzyme occurs primarily in epidermis and hair follicles. Cells after treatment with proteases show greater transglutaminase activity. The activated enzyme in rat chondrosarcoma cells is one of 95 K daltons, whereas mouse epidermal cells and rabbit endometrium cells after protease activation display enzymes of both 95 K daltons and 50 K daltons. The 95 K dalton enzyme, but not that of 80 K daltons, can be activated by proteases or sulfhydryl compounds after cell lysis. In cells that undergo terminal differentiation, e.g., reticulocytes, megakaryocytes, monocytes, chondrocytes, and epidermal cells, the forms of transglutaminase are modulated. Our findings suggest that these modulations in differentiating cells are the results of transglutaminase post-translational modifications that cause pronounced changes in catalytic activity.

Animals↗
PubMed1986

Nutritional improvement of legume proteins through disulfide interchange.

Treatment of raw soy flour with L-cysteine or N-acetyl-L-cysteine results in the introduction of new half-cystine residues into sulfur-poor legume proteins, with a corresponding improvement in nutritional quality as measured by the protein efficiency ratio (PER) in rats. The proteins are modified through formation of mixed disulfide bonds among added sulfhydryl compounds, proteolytic enzyme inhibitors, and structural legume proteins. This modification leads to loss of inhibitory activity and increased protein digestibility and nutritive value. Sodium sulfite is more effective than cysteine in facilitating inactivation of trypsin inhibitors in soy flour. The synergistic effect of sodium sulfite and heat may be due to ability to induce rearrangement of protein disulfide bonds to produce new structural entities without altering the amino acid composition and to the fact that the new structures lose their ability to complex with trypsin or chymotrypsin. The same treatment inactivated hemagglutinins (lectins) in lima bean flour. These considerations suggest a key role for sulfur amino acids in the nutritional quality and safety of legumes.

Acetylcysteine↗
PubMed1996

Engineering of a functional interleukin-5 monomer: a paradigm for redesigning helical bundle cytokines with therapeutic potential in allergy and asthma.

Interleukin (IL) 5 specifically induces the differentiation of eosinophils which are central to the pathogenesis of allergies and asthma. Structurally, IL-5 is a unique member of the short-chain helical bundle subfamily of cytokines. In contrast to other subfamily members which fold unimolecularly into a single helical bundle, IL-5 forms a pair of helical bundles by the interdigitation of two identical monomers covalently linked by a pair of intermolecular disulfide bonds. Although a native IL-5 monomer lacks bioactivity, we recently reported the engineering of an insertional mutant of IL-5 (designated mono5) which folds unimolecularly into a single helical bundle and has biological activity similar to that of native IL-5. Here we demonstrate no differences in signal transduction pathways utilized by mono5 and IL-5, as determined by western blot analysis of early tyrosine phosphorylation events, Jak2 activation, and mitogen-activated protein kinase activation. However, binding studies utilizing conformationally dependent neutralizing anti-IL-5 monoclonal antibodies localized a tertiary structural perturbation near the insert of mono5. This perturbation enabled localization of a limited region of the tertiary structure of IL-5 that engages the IL-5 receptor alpha-chain. Fluorescent labeling studies further revealed that the cysteines of mono5 contained free sulfhydryl groups, thereby demonstrating that the role of the disulfide bonds of IL-5 is the structural maintenance of other functional domains. The retention of conformation epitopes by mono5, but not IL-5, under reducing conditions and the equivalent thermostability of mono5 and IL-5 despite the absence of a disulfide bond in mono5 indicated that the conformation assumed by mono5 is very stable. In addition to providing the structural framework for designing novel IL-5 agonists and antagonists, the knowledge gained from the development of mono5 will enable other helical bundle proteins to be redesigned with therapeutic potential.

Antibodies, Monoclonal↗
PubMed1984

Studies with a human plasma-derived immunosuppressive, anti-lymphoma factor.

A low-molecular-weight (1,400) factor isolated from a human plasma alpha-globulin concentrate by acid-salt dissociation and ultrafiltration inhibits proliferation of mitogen-stimulated T cells and L1210 leukemia cells. The factor (UM05R) inhibits DNA, RNA, and protein synthesis in sensitive cells, acts in G1 of the cell cycle, and appears to suppress mitogen-responsive T cells without an accessory cell requirement. UM05R activity is enhanced by known cAMP-elevating agents and by sulfhydryl compounds. The results of the present study are consistent with the hypothesis that the plasma-derived agent inhibits lympho-proliferation as a result of elevation of intracellular cAMP.

Animals↗
PubMed1990

Stage-dependent appearance of sulfhydryl oxidase during spermatogenesis in the testis of rat and hamster. An immunohistochemical study.

Sulfhydryl oxidase (SOx), an enzyme that catalyzes the oxidation of sulfhydryl compounds, appears in the spermatogenic cells of rat and hamster testes in a stage-dependent manner. It first appears in pachytene spermatocytes at stage I in both the animal species studied. SOx immunoreactivity is associated with mitochondria of these cells. The fate of such mitochondria is species-dependent. In rat, the immunoreactive mitochondria aggregate during maturation phase and are retained in the residual bodies. Spermatozoa free of SOx are released into the lumen. On the other hand, in hamster, the immunoreactive mitochondria arrange themselves around the midpiece of spermatozoa. In such a case, residual bodies lack SOx. The appearance of SOx coincides with the appearance of LDH-X in the spermatogenic cells. Like many other proteins such as LDH-X, RSA-1 and cytochrome ct, SOx provides yet another example of differential gene activation associated with a developmental process of gametes.

Animals↗
PubMed1980

Induction of sister chromatid exchanges by hydroxylamine, hydrazine and isoniazid and their inhibition by cysteine.

Experiments were performed in order to gain information about the primary process leading to the production of sister chromatid exchanges (SCEs). Radical-forming substances (hydroxylamine, hydrazine and the antituberculous drug isoniazid) were examined for their effectiveness in inducing SCEs. All three substances proved successful in the induction of SCEs in the V-79 cell line of the Chinese hamster. By simultaneous application of a sulfhydryl compound (cysteine), a reduction of the hydrazine- and isoniazid-induced SCEs was achieved. Isoniazid was additionally examined in the in vivo SCE-test. At concentrations of 2-100 mg/kg body weight, it does not increase the rate of SCEs in the bone marrow of the Chinese hamster.

Animals↗
PubMed1984

[N-Acetylcysteine as an antidote in accidental acrylonitrile poisoning].

Acute acrylonitrile intoxications are followed by loss of consciousness, convulsions, respiratory arrest, and may end fatally. Common cyanide antidotes have not proved to be effective. In previous animal experiments we could demonstrate that the cyanide antidotes show some protective effect only after oral acrylonitrile application. Only a minimal amount of inhaled acrylonitrile will be transformed into cyanide, in contrast to pharmacokinetics after oral intake. After acrylonitrile inhalation the toxic effect of the whole molecule ( cyanethylation ) is important, and sulfhydryl compounds show antidotal effects. Further animal experiments demonstrate the superior antidotal effects of N-acetyl-cysteine after acrylonitrile inhalation. Intravenous injection of N-acetyl-cysteine in high doses is recommended according to the treatment of paracetamol poisoning.

Acetylcysteine↗
PubMed1981

[Possibilities and limits of the quantitative demonstration of protein thiols with the DDD-reagent in cells of cervical epithelium (author's transl)].

From six patients, all with invasive carcinoma of the cervix uteri, two groups fo smear preparations, each consisting of eight samples, were taken: The first, group A, before and the second, group B, after mechanical removal of the discharge which was present in abundant quantities. All samples were treated for 24 h with DDD to reach the fast-reaching SH-groups, coupled with Fast Blue B and measured cytophotometrically at 560 nm. Without any exception, the neoplastic cells of group A showed significantly lower extinction values both of the nucleus and of the total cell, if compared to group B. The mean extinction difference amounts to 55% and is highly significant and some evidence is given that the viability of the cells plays an important role. For this reason, the quantitative evaluation of the DDD Fast Blue B does not seem to be useful for cytologic routine investigations.

Cervix Uteri↗
PubMed1982

Covalent protein binding of reactive adriamycin metabolites in rat liver and rat heart microsomes.

Covalent binding of 3H-labeled adriamycin metabolites to bovine serum albumin and microsomal protein is demonstrated in an aerobic incubation system with rat liver and rat heart microsomes, respectively, using exhaustive organic solvent extraction and gel chromatography. Covalent protein binding was dependent on active microsomes, NADPH, and oxygen and was inhibited by reduced glutathione and other sulfhydryl compounds. The anthracycline moiety was spectrophotometrically evidenced in the adriamycin metabolite(s) covalently bound to protein. Thus, enzymatic activation of adriamycin in the heart with consecutive covalent protein binding of reactive adriamycin semiquinone radicals may contribute to adriamycin cardiotoxicity.

Animals↗
PubMed1987

The -SH and SS positive components in dermal connective tissues: a study by N-(7-dimethylamino-4-methyl-3-coumarinyl) maleimide (DACM) stain.

Although -SH and SS positive components in dermal connective tissue have been observed by N-(7-dimethylamino-4-methyl-3-coumarinyl) maleimide (DACM) stain, their nature is as yet unknown. In our study, we stained several organs such as human skin, rabbit aorta, auricle, and trachea using DACM stain, and studied the distribution of -SH groups and SS linkages among the elastic fibers in those organs. In the dermis of human skin, a moderately strong fluorescence by both -SH and SS stain was present all over the layer, especially in the lower half among collagen fibers in a fine linear or wavy pattern, and a fluorescence ascending vertically from the lower papillary dermis toward the epidermis was also observed. In rabbit aorta, a strong fluorescence by both -SH and SS stain was observed on well-developed elastic fibers. In the matrix of rabbit elastic cartilage, a strong reticular fluorescence by both -SH and SS stain was present. On the other hand, in rabbit hyaline cartilage, no -SH fluorescence was present on any components of the cartilage. However, though a diffuse moderate fluorescence for SS linkages was observed in the matrix, there was no reticular fluorescence such as that seen in the elastic cartilage. These results suggest that the -SH and SS components observed in the dermis by DACM stain are in fact elastic fibers, more precisely, "elastic tissue microfibrils".

Animals↗
PubMed1979

[Determination of the antibacterial activity of various mycotoxins using Bacillus thuringiensis (Berliner)].

Antibacterial activity of pure preparations of mycotoxins, was studied against strains of Bacillus thuringiensis (Berliner). Most of fungal metabolites used provokes: 1) Growth bacterial inhibition similar to lethal effect of antibiotics 2) Enlargment of cell volume; this cell abnormality induction resembles those obtained with mitomycin C. The bioassay of fungal toxins with B. thuringiensis can be recommended as a sensitive technique to supplement chemical characterization. By using specific cell lines to such a mycotoxin and specific inactivators as coumarin for aflatoxin, or sulfhydryl compounds for penicillic acid and patulin.

Aflatoxins↗
PubMed1996

Inhibition of yeast-to-mycelium conversion of Candida albicans by conjugated styryl ketones.

Candida albicans is a dimorphic pathogenic yeast capable of producing alternate morphological forms (yeast or mycelium) in response to environmental changes. The dimorphism of C. albicans plays an important role in the pathophysiology of this organism. The intracellular level of glutathione, which helps to maintain the oxidation-reduction potential of the cell, is decreased significantly during the yeast-to-mycelium conversion implicating the possible involvement of thiols in the yeast-to-mycelium transition. To evaluate the possible participation of sulphydryl group(s) containing component(s) in the yeast-to-mycelium transition of C. albicans, we examined the effect of a group of newly synthesized thiol-alkylators on the production of germ tubes from yeast cells. Several conjugated styryl ketones which are thiol-alkylators, and p-chloromercuriphenylsulphonate (a known nonpenetrating thiol-blocker) inhibited the yeast-to-mycelium conversion of C. albicans. The thiol-alkylators at 20 microM failed to inhibit four key enzymes (gamma-glutamyltranspeptidase, glutathione reductase, glutathione S-transferase and glutathione peroxidase) involved in glutathione utilization indicating that the inhibition of yeast-to-mycelium conversion is not mediated by the inhibition of glutathione metabolic enzymes. Moreover, these results suggest that a key thiol-blocker sensitive component(s) containing a critical sulphydryl group(s) is involved in the yeast-to-mycelium transition of C. albicans.

4-Chloromercuribenzenesulfonate↗
PubMed1976

SH groups in the alpha-naphthyl acetate esterase in the thyroid of the guinea-pig. A histochemical study.

The alpha-naphthyl acetate esterase in both group I and group II thyroid cells is shown to contain SH groups since there is a decline in activity in both cell groups when certain sulfhydryl reagents [DTNB; 5,5'-Dithiobis-(2-nitrobenzoic acid)-AgNO3-Mersalyl-PCMB (parachloro mercuribenzoate) + urea] are added to the incubation media. Thus the inhibition is by far the greatest in group I cells, which also show the greatest activity after incubation in conventional media, when long fixation and storage times are used. In all cases the inhibiting effect was complete or almost completely reversed if cysteine was added to the incubation media in equivalent concentrations to the SH blocker. There were great differences among the sulfhydryl reagents used in their ability to bring about enzyme inhibition. The alkylating agents NEM (N-ethylmaleimide) and iodoacetamide had no or little effect while PCMB could only inhibit the activity of the alpha-naphthylacetate esterase if the enzyme was denaturated with 5 M urea. The maximal inhibitory effect of PCMB was only obtained when NaCl was added to the incubation media. The most effective inhibitor was AgNO3.

Animals↗
PubMed1976

Membrane SH-groups related to adrenaline action in rat adipocytes: a comparative study using sulfhydryl reagents of different molecular size.

The orientation of SH-groups within the fat cell membrane involved in adrenaline (and NaF) action was studied by comparing the effects of uncoupled p-CMB with those of a large derivative of this reagent -- p-CMB-dextran --. Preincubation of intact adipocytes with uncoupled p-CMB caused a dose-dependent inhibition of adrenaline (and NaF) stimulated adenylate cyclase activity as determined in ghosts prepared subsequently. Preincubation with p-CMB-dextran, however, influenced neither the lipolytic response to adrenaline nor the catecholamine (and NaF) activated adenylate cyclase activity. When p-CMB-dextran was present during ghost preparation, a dose-dependent inhibition of adrenaline (and NaF) stimulated adenylate cyclase activity was observed. These results suggest that the binding sites of adrenaline as well as SH-groups essential for activity of adenylate cyclase are not localized near enough to the exterior surface to be accessible for p-CMB-dextran. The polarity in the sensitivity of fat cell adenylate cyclase could not be observed when p-CMB-dextran was added directly to intact or fragmented ghosts. The abbreviations used are: Cyclic AMP, cyclic adenosine 3',5'-monophosphate; p-CMB, p-chloromercuribenzoate.

Adenylyl Cyclases↗
PubMed1976

The fate of phenylhydroxylamine in human red cells.

Phenylhydroxylamine added to human red cells under aerobic conditions and in the presence of glucose was partly reduced to aniline. About half the hydroxylamine was recovered as amine after a 2-hr incubation. The aniline, after acetylation, was identified as acetanilide by melting point, Rf-value in TCL as well as UV, IR, and NMR spectroscopy. The fate of the remaining phenylhydroxylamine was followed by use of 14C-labeled phenylhydroxylamine. About 30% of the total radioactivity was bound to hemoglobin or other proteins and about 20% was found in highly polar low-molecular substances which were insoluble in organic solvents. The elucidation of the sites at which phenylhydroxylamine was bound to hemoglobin was complicated by the lability of the bonds. When purified human hemoglobin had reacted with radioactive phenylhydroxylamine, large proportions of the radioactivity bound to hemoglobin were removed by treatment with acid or with PMB for separation of alpha- and beta-chains. The radioactive compound liberated from hemoglobin by acid was found to be aniline. After reaction with phenylhydroxylamine the number of SH groups titrable with PMB was found to be diminished. Pretreatment of hemoglobin with N-ethylmaleimide or PMB decreased the amount of phenylhydroxylamine bound to hemoglobin but did not fully prevent the reaction. Tryptic digestion of hemoglobin after reaction with radioactive phenylhydroxylamine yielded tryptic peptides with lower specific activity than that of hemoglobin. Chymotryptic digestion of the tryptic core yielded a core with specific activity much higher than that of hemoglobin. Fingerprinting of the tryptic or chymotryptic hydrolyzates showed the presence of peptides with high and other ones with low or no radioactivity and of radioactive compounds which did not react with ninhydrin. In the covalent binding of phenylhydroxylamine to globin the SH group beta93 plays an important role, but other yet unknown sites are also reactive.

Acetanilides↗
PubMed1991

Immunohistochemical distribution of sulfhydryl oxidase in the human testis.

Sulfhydryl oxidase (SOx) is an enzyme that catalyzes the oxidation of sulfhydryl compounds. It is present in mitochondria of certain testicular cells at specific stages of functional activation. In the mature human testis moderate SOx immunoreactivity is found in Leydig cells, and lacking in Sertoli and in peritubular cells. The Adark spermatogonia usually contain immunoreactive mitochondria, while in Apale spermatogonia immunoreactivity is mostly low. In stage V of spermatogenesis, Apale spermatogonia were found containing immunoreactive material. Leptotene (stages IV and V) and zygotene (stage VI) primary spermatocytes display a moderate immunoreaction. It is strongest in pachytene spermatocytes of stages I-IV, decreases in stage V, and is low during diakinesis and in secondary spermatocytes. Late spermatids usually show a stronger immunoreactivity than early spermatids. At stage V of spermatogenesis the late spermatids contain only few immunoreactive particles. Spermatozoa are free of SOx-immunoreactive mitochondria. In residual bodies small amounts of SOx-immunoreactive particles are seen. Compared to rat and hamster testis, SOx immunoreactivity of the human testis is less clearly stage-dependent and it is not confined to certain germ cell stages. As deduced from the findings in patients with spermatogenic disorders, the SOx immunoreactivity of spermatogonia in human testis seems to be of diagnostic relevance.

Adult↗