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PubMed1987

A method for the quantification of a colored or fluorescent signal in enzyme immunoassays by photodensitometry.

A colored or fluorescent signal is generally evaluated with the naked eye, or by means of different more or less sophisticated and costly instruments. Photodensitometry is an additional technique which is both inexpensive and simple to perform. This technique can satisfactorily quantify a signal without the use of either a spectrophotometer or a fluorometer. In this study we compared readings obtained by spectrophotometry, fluorometry and photodensitometry in 96-well ELISA plates and in Terasaki plates. In ELISA plates, it is possible to detect 1220-300,000 femtograms (fg) of peroxidase by spectrophotometry and 4800-125,000 fg by photodensitometry. In Terasaki plates, we were able to measure between 3.8 and 8000 fg of beta-galactosidase per sample by spectrofluorometry, and from 30 to 8000 fg by photodensitometry. Using a sandwich procedure in Terasaki plates we were able to measure between 100 and 10,000 fg of IgE per sample by spectrofluorometry and from 500 to 10,000 fg by photodensitometry. Photodensitometry is the least expensive technique for the reliable detection of enzyme or enzymatic marker in small sample volumes treated with a fluorogenic substrate.

Chromogenic Compounds↗
PubMed1988

Quantitation of related proteins by Western blot analysis.

A spectrophotometric assay for quantitation of related proteins following Western blot analysis is described. Proteins were separated by polyacrylamide gel electrophoresis and electrophoretically transferred to nitrocellulose. In the system utilized in this study, immobilized interleukin-1 (IL-1) proteins were identified by ELISA reaction using a rabbit antibody specific for IL-1 beta. Subsequently, the membrane was probed with goat anti-rabbit antibody conjugated to horseradish peroxidase and IL-1 proteins were detected by incubation with 4-chloro-1-naphthol and hydrogen peroxide. The stained IL-1 bands were cut out, exposed to the peroxidase chromogenic substrate, o-phenylenediamine (OPD), and hydrogen peroxide and the rate of reaction was determined spectrophotometrically at 490 nM. A linear relationship between enzyme activity and IL-1 concentration was observed from 10 to 1000 ng/lane. Thus, this represents a sensitive and specific method for quantitating small amounts of IL-1 in complex protein mixtures.

Chromogenic Compounds↗
PubMed1988

A novel two colour ELISPOT assay. I. Simultaneous detection of distinct types of antibody-secreting cells.

A novel assay system has been developed which is based on the ELISPOT methodology and employs a combination of two immunoenzyme visualization systems yielding distinct colour products. This variation permits the simultaneous enumeration of two different types of cell secreting antigenically distinct products. Optimal conditions for the concurrent detection of human mononuclear cells secreting IgG or IgA antibodies are described.

Adult↗
PubMed1988

Concurrent assessment of inner and outer membrane permeabilization and bacteriolysis in E. coli by multiple-wavelength spectrophotometry.

We developed a dual wavelength spectrophotometric assay that permitted beta-lactamase and beta-galactosidase activities to be measured concurrently in a single sample. We also constructed a target cell, E. coli ML-35p, that was substantially cryptic for its periplasmic beta-lactamase and cytoplasmic beta-galactosidase unless outer membrane (beta-lactamase) or inner membrane (beta-galactosidase) permeabilization occurred. By applying the spectrophotometric assay to whole target cells, we could ascertain the kinetics of inner and outer membrane permeabilization by biological agents, including serum, polymyxin B and mellitin. By monitoring the reactions at an additional wavelength, we could also follow the kinetics of serum-mediated bacteriolysis. These experiments illustrate the principle of multiple wavelength spectrophotometry and provide examples of its use to monitor and dissect the action of biological agents on a gram-negative bacterium.

Bacteriolysis↗
PubMed1982

Comparison of genetic and endocrine control of renin and kallikrein in mouse submandibular gland.

The effects of strain, sex, hypophysectomy and hormone treatment on mouse submandibular gland renin, kallikrein, S2266 hydrolase, and BAEe esterase activities have been examined. Renin activity is determined by the Rnr locus on mouse Chromosome 1. Female SWR/J mice (Rnrs/Rnrs) have 1000-fold higher submandibular gland renin activity than C57BL/6J mice (Rnrb/Rnrb). Both strains have similar kallikrein activity. Renin, BAEe esterase, and S2266 hydrolase are substantially higher in male mice compared to females of the same strain whereas kallikrein is not. Dihydrotestosterone and/or thyroxine treatment induces renin, BAEe esterase, and S2266 hydrolase in female mice with little effect on kallikrein. All four enzyme activities are profoundly reduced by hypophysectomy. Dihydrotestosterone and thyroxine are both required to restore renin, BAEe esterase, and S2266 hydrolase to induce levels. Dihydrotestosterone and/or thyroxine restores kallikrein to control levels. We conclude that renin and kallikrein in the mouse submandibular gland are under different genetic and endocrine control. In addition, the synthetic substrate S2266 is not a specific substrate for kallikrein activity in mouse submandibular gland cytosol.

Animals↗
PubMed1995

Interlaboratory comparison: liver spontaneous mutant frequency from lambda/lacI transgenic mice (Big Blue) (II).

Spontaneous mutant frequency in livers of two transgenic mouse strains, each carrying identical lambda shuttle vectors with a lacI target gene, was evaluated by two laboratories. These studies investigated variability in spontaneous mutant frequency between animals and as a function of the number of phage screened. Liver DNA was independently isolated from 7-11 week old C57BL/6 and B6C3F1 Big Blue transgenic mice. At least 500,000 phage were screened for mutation at lacI for each animal using standardized assay procedures. In the two labs, the C57BL/6 liver spontaneous mutant frequency was 45 +/- 9 x 10(-6) and 41 +/- 7 x 10(-6). The B6C3F1 liver spontaneous mutant frequency was 42 +/- 10 x 10(-6) at one lab and 43 +/- 12 x 10(-6) and 41 +/- 8 x 10(-6) in two trials at the second lab. Mean mutant frequency data from both labs, calculated in increments of 100,000 plaque forming units (pfu) scored for each mouse strain, show stabilized mean mutant frequency and standard deviation after approximately 200,000-300,000 pfu screened. The frequency of spontaneous lacI mutants was reproducible both within and between labs and was comparable between the two transgenic mouse strains.

Animals↗
PubMed1995

Intralaboratory optimization and standardization of mutant screening conditions used for a lambda/lacI transgenic mouse mutagenesis assay (I).

A lambda/lacI shuttle vector transgenic mouse mutagenesis assay has been optimized and standardized for reproducible mutant detection. The mutagenic endpoints are blue lacI- phage plaques on a bacterial lawn resulting from the de-repression of beta-galactosidase activity acting on the chromogenic substrate X-gal. Non-mutant lacI phage plaques remain colorless. Factors demonstrated to affect mutant detection include X-gal concentration per assay tray, plaque density per assay tray, pH of plating agar, incubation time at 37 degrees C and the use of a red translucent screening filter over a light source to enhance mutant plaque visibility. In vivo mutant frequencies for liver in untreated animals using standard protocols and internal controls were repeatable in separate experiments using lambda/lacI B6C3F1 mice (4.3 +/- 1.2 x 10(-5) and 4.1 +/- 0.8 x 10(-5)). These studies analyze the use of internal controls to monitor the level of mutant phage plaque detection in a given experiment and evaluate the repeatability of observed mutant frequencies obtained when using standardized procedures.

Agar↗
PubMed1985

Chromogenic proteinase substrates as possible tools in the characterization of Crotalidae and Viperidae snake venoms.

Proteinase activities have been determined photometrically in 25 different Crotalidae and Viperidae snake venoms by using five different chromogenic proteinase substrates. The activity profiles obtained by listing the identity numbers of substrates hydrolyzed by the venoms in a decreasing potency order remained quite stable within a given snake population. Submission of a venom to various physical and chemical treatments did not alter its activity profile. It is therefore concluded that this simple method of determining proteinase activities could be of help in snake venom characterization, as well as in studying the influence of metallic ions and inhibitors of snake venom proteinases.

Animals↗
PubMed1986

Comparison of two methods for proteolytic enzyme detection in snake venom.

An acrylamide gel system containing fibrinogen was used to detect proteolytic enzymes in snake venoms. Proteolytic activity was observed as a clear area on a blue background after electrophoresis and overnight incubation in Tris buffer, prior to staining with Coomassie blue. Venoms from eastern and western diamondback and west coast Mexican rattlesnakes, Crotalus adamanteus, C. atrox and C. basiliscus basiliscus, respectively, and southern copperhead, Agkistrodon contortrix contortrix, were analyzed at the level of 1 mg of venom. The effect of the serine proteinase inhibitor diisopropylfluorophosphate (DFP) and the metalloproteinase inhibitors tetraethylenepentamine (TEP) or EDTA on fibrinogen and normal gel profiles were evaluated. Normal gels (without fibrinogen) were Coomassie stained to visualize migration of 250 micrograms of venom proteins on the gels. Several proteolytic enzymes detected in C. atrox and C. b. basiliscus venoms were inhibited by TEP, whereas DFP had no effect on activity. The fibrinogen gels detected no protease activity in C. adamanteus venom, although it is known from other studies that there are several proteolytic enzymes in this venom. Several proteases were detected in A. c. contortrix venom, one of which was inhibited by TEP. By comparison, proteolytic activity in 5-10 micrograms of all venoms was readily detected using the mammalian plasma kallikrein specific chromogenic substrate, S2302 (H-D-Pro-Phe-Arg-p-nitroanilide). The fibrinogen gel method does not appear to have the specificity nor the sensitivity of the recently developed chromogenic substrates for detection of proteolytic enzymes in snake venom.

Animals↗
PubMed1991

Procoagulant activities in venoms from central Asian snakes.

The venoms from central Asian snakes (Echis carinatus, Echis multisquamatus, Vipera ursini, Vipera lebetina, Agkistrodon halys halys and Naja naja oxiana) contain several enzymes with amidolytic- and procoagulant activity. We have characterized the activities and the mol. wts of the venom enzymes that are able to convert a number of commercially available chromogenic substrates for activated coagulation factors. The chromogenic substrate cleavage patterns obtained for the crude venoms may be helpful tools in the further identification of venom fractions and venom enzymes with procoagulant activity. The crude venoms were also tested for their ability to clot fibrinogen, to lyse fibrin polymers and to activate the coagulation factors prothrombin, factor X and factor V. The products of venom-catalyzed coagulation factor activation were structurally characterized by SDS gel electrophoresis and were compared with activated coagulation factors that are generated under physiological conditions.

Amides↗
PubMed1994

Isolation and characterization of Textarin, a prothrombin activator from eastern brown snake (Pseudonaja textilis) venom.

The venom of P. textilis contains two different enzymes which convert human prothrombin into thrombin. Prothrombin activation by Textarin, a serine proteinase containing a calcium-binding molecule site, with a molecular mass of 50,000 to 53,000 Da and I.P. 5.5, separated from crude venom by either barium citrate adsorption or hydroxyl apatite chromatography, is strongly stimulated by phospholipid and calcium ions. A second activator, found in the supernatant of barium citrate adsorbed venom solution, activates prothrombin in the absence of any co-factor. Human plasma coagulation induced by Textarin, phospholipid and calcium ions is affected by lupus anticoagulants. Textarin may thus be used for the detection of lupus anticoagulants in patient plasma samples.

Amino Acid Sequence↗
PubMed1994

Studies on venom and venom apparatus of Fea's viper, Azemiops feae.

Enzyme activities tested in the venom gland extract of Azemiops feae snake are similar to those of viperine venoms, except that Azemiops venom has no blood clotting, haemorrhagic or myolytic activities. The venom gland exhibits the characteristic feature of a viperine gland, but the fangs possess a ridge at the tip laterally to the venom orifice and a blade-like structure on the back seen only in some opisthoglyphous and Atractaspidae snakes.

Amino Acid Oxidoreductases↗
PubMed1995

Purification and characterization of piscivorase I and II, the fibrinolytic enzymes from eastern cottonmouth moccasin venom (Agkistrodon piscivorus piscivorus).

Fibrinolytic enzymes, piscivorase I and II, were isolated from Agkistrodon piscivorus piscivorus (eastern cottonmouth moccasin) venom using gel filtration on Bio-Gel P-100 and ion-exchange chromatography on CM-Sepharose CL-6B. The mol. wts of these proteases, piscivorase I and II, are 23,400 and 29,000 and isoelectric points are 6.6 and 8.5, respectively. These fibrinolytic enzymes were homogeneous by SDS-polyacrylamide gel electrophoresis. Piscivorase I readily cleaved the A alpha- and B beta-chain of fibrinogen, but piscivorase II cleaved readily the A alpha-chain and more slowly the B beta-chain. These fibrinolytic enzymes were activated by Ca2+, Mg2+ and Ba2+, but inhibited by Zn2+, Cu2+ and Mn2+. Both fibrinolytic enzymes were also inhibited by cysteine, beta-mercaptoethanol, and by metal chelators such as EDTA and EGTA, but not by benzamidine, phenylmethanesulfonyl fluoride (PMSF), soybean trypsin inhibitor and aprotinin. These fibrinolytic enzymes did not act like thrombin, plasmin and kallikrein, using specific chromogenic substrates. Neither fibrinolytic enzyme induced platelet aggregation, and piscivorase I showed low haemorrhagic activity at dosages of 55 micrograms.

Amino Acids↗