Effect Of Certain Inhibitors Research Articles

Study of the gelatinolytic activities of Escherichia coli cells before and after starvation in seawater by substrate gel electrophoresis

Previous work has shown that clinical Escherichia coli strains, starved in seawater, are able to present residual growth, with subsequent alterations to their enzymatic activities and metabolism. Gelatinolytic activity of starved cells is of importance because it appears and increases gradually with time. In this work, several forms of gelatinolytic activity were detected by SDS-polyacrylamide gel electrophoresis, differing in molecular masses and appearance, before and after starvation of E. coli cells. The enzymic forms are classified into 4 categories according to the effect of certain inhibitors on the appearance of gelatinolytic activity: a. those whose appearance is inhibited by the chelating factors EDTA, 1, 10-phenanthroline and whose presence is also inhibited by N-ethylmaleimide (metalloproteinases with thiol group active); b. those affected by the presence of chelators, N-ethylmaleimide and Ca 2+ (Ca 2+-dependent metalloproteinases with thiol group active); c. those inhibited by chelators and activated in the presence of Ca 2+ (Ca 2+-dependent metalloproteinases) and d. those whose appearance is independent of the presence of inhibitors used. The forms of gelatinolytic activity of the fourth category coincide with enzyme forms that can also use cascin as substrate in electrophoresis. These data suggest that there are considerable differences in the gelatinolytic pattern of clinical strains of E. coli cells before and after starvation in seawater.

Evidence of active transport of cadmium complexing dithiocarbamates into renal and hepatic cells in vivo.

A study was made of the effects of certain inhibitors of transport systems on the actions of four cadmium (Cd) complexing N,N-disubstituted dithiocarbamates (DTCs) in mobilizing murine renal and hepatic Cd in vivo. Probenecid, the prototypical antagonist of organic anion transport in the kidney, when given 1 hr prior to each DTC, sharply suppressed the DTC-induced reduction of renal Cd but was virtually without effect on mobilization of Cd from liver. Sulfinpyrazone, which blocks tubular reabsorption of uric acid and also inhibits transport of a variety of organic acids, inhibited markedly the mobilization of both renal and hepatic Cd by DTCs. Phlorizin, an inhibitor of tubular sugar reabsorption, did not affect the Cd mobilizing actions of DTCs in any consistent fashion. We propose that the high degree of selectivity of DTCs in mobilizing renal and hepatic Cd is dependent, at least in part, upon active transport of DTCs into these tissues via the organic anion transport systems. This report presents the first evidence that compounds of the (R)2NCSS- class may gain access to intracellular space by an active, carrier-mediated process.

A novel serine esterase expressed by cytotoxic T lymphocytes.

Cytotoxic T (Tc) lymphocytes recognize and lyse target cells and are thought to serve as an important defence against viral infections and possibly against neoplasms. The nature of the receptors responsible for antigen recognition by these cells is becoming clearer, but the molecular mechanisms responsible for their cytolytic activity remain largely unknown. The possibility that proteases are involved in this process has been suggested by the effects of certain inhibitors. Here we demonstrate that clones of murine Tc cells possess considerable trypsin-like esterase activity when assayed by a sensitive colorimetric assay. This activity was blocked completely by two serine esterase inhibitors, diisopropylfluorophosphoridate (DFP) and phenylmethylsulphonyl fluoride (PMSF), but not by N alpha-tosyl lysyl chloromethyl ketone (TLCK). The use of 3H-DFP as an affinity-labelling reagent demonstrated that the esterase activity resides in a protein of relative molecular mass (Mr) 28,000 (28K). A wide variety of other lymphocytes, including those from thymus, spleen and lymph node, established lines of B cells and noncytotoxic T cells, and clones of T helper cells, had about 300-fold less esterase activity than the Tc-cell clones and far smaller amounts of the DFP-reactive 28K protein. However, in thymocytes the esterase activity increased 20-50-fold and the 28K protein became more prominent 4 days after these cells had been stimulated in vitro to generate Tc cells.

Corrosion effects of decomposition of organic fibre cores and pyritic dusts on wire ropes

AbstractThe effects on the corrosion of wire rope for mining applications of the breakdown products of reactions between organic fibre materials and lubricants, with and without contaminants, have been studied. Oxidation of pyritic mine dusts in the presence of corrosion debris to form acidic products is also discussed, and the effectiveness of certain inhibitors is assessed. It has been observed that decomposition of fibre core material contaminated with commercial lubricants and the interaction of the impure layer of corrosion products with mine dusts combine to accelerate the corrosion of wire ropes inside mines. Decomposition of the organic manila fibre appears to form acidic reaction products in the presence of certain contaminants, such as lubricants: commercial manila fibre decomposes to form alkaline products in the absence of contaminants. Corrosion debris appears to promote the oxidation of pyritic mine dusts to form acidic products. Benzylamine in low concentrations was found to be a good inhib...

Effect of Certain Inhibitors of Glycoprotein Synthesis on Cell Fusion Induced by Vesicular Stomatitis Virus

The effect of certain metabolic inhibitors on the fusion of BHK-21 cells induced by vesicular stomatitis virus (VSV) was studied. The polykaryocyte formation in infected cells and virus growth were inhibited by 2-deoxy-D-glucose and D-glucosamine. Host-cell proteins synthesis was suppressed profoundly in both BHK-21-KB and B cells infected with VSV. On the other hand, glycoprotein synthesis was significantly enhanced during the polykaryocyte formation in BHK-21-KB cells, while it was suppressed in BHK-21-B cells which were not sensitive to cell fusion by VSV.

Effect of certain inhibitors on corrosion-mechanical fracture of steel in hydrochloric acid

Effect of certain inhibitors on corrosion-mechanical fracture of steel in hydrochloric acid

The quality control of alkaline phosphatase determinations with placental phosphatase

Human placenta has been recommended as the source of the alkaline phosphatase used for the preparation of control or reference materials. The effect of certain inhibitors, which may be present in the reagents, on control materials containing the placental isoenzyme, is shown to differ significantly from their effect on the isoenzymes in patient's sera. This finding indicates that if control materials are used which contain only human placental alkaline phosphatase, changes in accuracy resulting from differences in reagent quality may be missed, or alternatively a change in accuracy may be indicated by the quality control results which does not apply to the patient's sera.

Effects of Certain Inhibitors on Photorespiration by Wheat Leaf Segments

The effect on the carbon metabolism of wheat leaf segments of certain inhibitors of photo respiration was studied. Sodium 2-hydroxy-3-butynoate supplied for 40 min resulted in accumulation of 14C in glycolic acid with only a 7% inhibition of photosynthesis ; when supplied for 90 min, photosynthesis was inhibited by 47%. When 14C02 was replaced by 1000 vpm 12C02, radioactivity in glycine decreased but increased more rapidly in sucrose with less release of 14C02. Isonicotinyl hydrazide (INH) inhibited photosynthesis from 14C02 by 50% and glycine replaced sucrose as the main product. When, after 15 min, 14C02 was replaced by 150 vpm 12C02, in the presence of INH less 14C02 was released, 14C in glycine decreased more slowly, and less [14C]sucrose accumulated. Glycidate (potassium 2,3-epoxypropionate) at 2 mM had no effect on photosynthetic rate and little effect on carbon metabolism ; 20 mM glycidate inhibited photosynthesis by 64% and resulted in less radioactivity in glycine, more in phosphate esters, and less 14C02 released. When photosynthesis was measured in 1000 vpm C02 the inhibitors gave smaller effects on metabolism than during photosynthesis from 150 vpm 14C02 but 20 mM glycidate still resulted in a 42% inhibition of photosynthesis. When U - [14C]glycerate was applied to leaf segments in air with 320 vpm 12C02 the total uptake of glycerate was not changed by the inhibitors. INH and glycidate both decreased the amount of glycerate metab olised. More 14C accumulated in glycine in the presence of INH and in phosphate esters and serine in the presence of glycidate. Hydroxybutynoate increased the production of glycolate from glycerate but did not affect the total amount of glycerate metabolised. Although all three inhibitors affected photorespiratory metabolism none stimulated photo synthesis. The results are consistent with the main release of C02 in photorespiration arising from the conversion of glycine to serine.

Effect of certain inhibitors of nucleic acid and protein synthesis on the growth and development of amine oxidase and ascorbate oxidase in germinating peas

Effect of certain inhibitors of nucleic acid and protein synthesis on the growth and development of amine oxidase and ascorbate oxidase in germinating peas

The effect of certain inhibitors of prostaglandin biosynthesis on flowering of Pharbitis nil

Certain inhibitors of prostaglandin biosynthesis in mammalian systems, namely, aspirin, phenylbutazone, indomethacin and niflumic acid inhibit flowering of Pharbitis nil to a greater or lesser extent.

Factors affecting the precipitation of calcium phosphate in vitro.

The precipitation of calcium phosphatein vitro was studied in order to define the processes of homogeneous and heterogeneous nucleation and to study the effect of certain inhibitors of crystallization on these processes. It was shown that the solubility-determining surface phase of the calcium phosphate formed by homogeneous nucleation had a Ca/P molar ratio close to that of octacalcium phosphate (OCP) and that the most constant formation product in solution at the onset of spontaneous precipitation was that of OCP. Known inhibitors of crystallization had no effect on the formation product of homogeneous nucleation. Below the formation product of spontaneous precipitation nucleation was essentially heterogeneous and was markedly influenced by adding nucleating material to the system, by increasing the time of incubation, and by adding inhibitors of crystallization containing the grouping P-X-P (where X=O, C, or N). The level of supersaturation at the point of maximum inhibition was close to the formation product of spontaneous precipitation of calcium phospate. The implications of these observations are discussed in relation to the precipitation of calcium salts in urine.

INHIBITION OF CHOLINE ACETYLTRANSFERASE AND ITS HISTOCHEMICAL LOCALIZATION

Abstract— A method for the histochemical identification of choline acetyltransferase has been investigated further by studying the effects of certain inhibitors of the enzyme both on rat brain homogenates and on the localization of the enzyme in tissue sections.It was confirmed that acetyl‐CoA hydrolase activity both in homogenates and in tissue sections is inhibited by preincubation in 1 mM‐DFP. The effects of the choline acetyltransferase inhibitors chloro‐ and bromoacetylcholine on the appearance of histochemical staining were related to their activity in homogenates and tissue slices. Bromoketone was found to inhibit choline acetyltransferase in homogenates and, less efficiently, in tissue sections but it also inhibited the hydrolysis of acetyl‐CoA by some other unknown enzyme which is inactivated by 1 mM‐DFP.The results obtained with the choline acetyltransferase inhibitors provide support for the specificity of the histochemical method.

Effect of antiviral agents in equine abortion virus-infected hamsters.

Equine abortion virus, a member of the herpesvirus group, produces a lethal infection in hamsters. With this system, the protective effect of certain inhibitors of deoxyribonucleic acid viruses, inducers of interferon and exogenous interferon, was evaluated. Of the various agents studied, 9-beta-d-arabinofuranosyladenine markedly suppressed mortality, and 5-iodo-2'-deoxyuridine, distamycin A, and N-ethylisatin beta-thiosemicarbazone were inactive. Of the inducers tested, statolon, ultraviolet-irradiated Newcastle disease virus, and polyriboinosinic:polyribocytidylic acid (poly I:C) were protective, and endotoxin, polyacrylic acid, and polymethacrylic acid did not protect. Administration of exogenous interferon did not afford protection. Statolon and ultraviolet-irradiated Newcastle disease virus induced circulating interferon in hamsters, whereas poly I:C, endotoxin, and polyacrylic acid did not produce interferon. Because of the severity of the disease produced in hamsters by equine abortion virus, lack of protective activity by an agent in this system should not preclude possible efficacy against other members of the herpesvirus group.

Some observations on the role of ATP in sieve tube translocation

Using the aphid stylet technique (14)C ATP was shown to be readily taken up into the sieve elements of willow. At the same time this compound was found to be metabolised during uptake resulting in labelled ADP and AMP appearing in the stylet exudate. Longitudinal movement of labelled ATP was also found to occur.Measurement of the levels of ATP and ADP in stylet exudate showed that both were present in high concentrations. The ratio ATP/ADP varied between 2.0 and 5.3.The effect of certain inhibitors of oxidative phosphorylation (oligomycin and DNP) and glycolysis (fluoride) on the rate of stylet exudation was studied. All three inhibitors caused a cessation of exudation but this did not occur until several hours after inhibitor application. Oligomycin and DNP had no effect on the concentration of ATP in the sap. Fluoride however, appeared in some cases to reduce the ATP concentration to a low level an hour or more before exudation finally stopped.Incorporation of (32)Pi into organic phosphate esters present in stylet exudate was found to occur within 15 minutes of the application of the tracer to a bark strip. Labelling of organic phosphates also took place, at a slower rate, when (32)P inorganic phosphate was incubated with stylet exudate.

Testicular lactate dehydrogenase isozyme

1. 1. Guinea pig's lactate dehydrogenase isozyme I B 4 from heart, 5 A 4 from skeletal muscle, and the two additional forms (X and X′) from mature testis have been isolated and partially purified. 2. 2. K m , optimum substrate concentration, inhibition by high concentration of substrate and the effect of certain inhibitors and pre-heating, showed values for X′ that were the average between those found for isozymes X and 5 (A 4). 3. 3. Dissociation and recombination of polypeptides in vitro indicated that X is a homopolymer of chains (C) different from A and B, and that X′ is a hybrid of A and C units. 4. 4. Association of C and A polypeptides in vivo is possible in the precursor cells of the gametogenic line in which synthesis of the additional unit is started. In mature spermatozoa this hybridization does not occur, probably because the activity of genes controlling production of A and B chains is “turned of”.

Effects of Certain Inhibitors on Renal Sodium Reabsorption and ATP Specific Activity

Sodium reabsorption in the kidney should be as closely related to ATP synthesis as it is to oxygen consumption. This problem was investigated in the present studies with the assumption that the uptake of inorganic phosphate by ATP is related to the rate of ATP synthesis. Radiophosphate was infused into anesthetized dogs in the course of renal clearance studies. The experimental protocols included the administration of compounds known to affect sodium reabsorption or renal cortical metabolism. At the termination of the function study, the renal cortices were removed and their nucleotides separated by column chromatography. The specific activity of ATP and sodium reabsorption in control studies were compared to values obtained in experimental studies. Sodium reabsorption was reduced with and without an effect on the specific activity of ATP. Conversely, ATP specific activity was reduced with and without an effect on sodium reabsorption. We conclude that a part of cortical sodium reabsorption can be energized other than by ATP metabolism.

Dissociatiion of esterase from proteinase activity of Bacillus subtilis spores.

Preparations of ballistically disintegrated Bacillus subtilis spores have been shown to possess proteinase in addition to esterase activities. Both proteinase and esterase activities have been suggested as trigger for the initiation of germination, but information on these two activities in bacterial endospores is scant. Since some proteinases catalyze the hydrolysis of esters, there exists a possible identity of some esterases with proteinases. To get information on the esterase and proteinase activities of B. subtilis spores, the sensitivity to heat and to inhibitors was explored. The thermal effect and the effect of certain inhibitors on esterase activities towards several esters suggested that an unspecific esterase was responsible for these activities.Differential effects of heat, pH, and inhibitors on esterase and proteinase activities indicated the dual nature of these two activities. In absence of convincing experimental evidence to the contrary, the present indication seems to be that the esterase activities observed in B. subtilis spores were dissociated from the activity which hydrolyzes casein. The esterase activity was readily inhibited by diethyl p-nitrophenyl phosphate, diisopropylphosphofluoridate, eserine, sodium fluoride, and Zn ions, and possessed properties of a B-esterase. The proteinase activity was inhibited only by diisopropylphosphofluoridate showing properties, so far studied, similar to subtilopeptidase.

Uphill transport of urea in the dog kidney: effects of certain inhibitors.

To study the renal medullary transport and accumulation of urea in dogs independent of water transport, we obliterated the medullary electrolyte gradient by a sustained ethacrynic acid diuresis. Infusions of urea were also given at various rates to vary urinary urea concentration. In the steady state, the kidneys were removed, and slices were analyzed for water, urea, and electrolytes. In every experiment in 15 dogs over a range of urinary urea concentration from 19 to 230 mmoles per L and urine flow from 0.5 to 9.7 ml per minute per kidney, an intrarenal urea gradient persisted, and urinary urea concentration was always lower than papillary water urea concentration. The magnitude of this uphill urinary-papillary gradient (mean +/- SE = - 21 +/- 2.9 mmoles per L) was not affected by hemorrhagic hypotension or a nonprotein diet. In 12 additional experiments begun similarly, inhibitors were infused into one renal artery. Both iodoacetate, an inhibitor of anaerobic glycolysis, and acetamide, an analogue of urea, markedly and significantly reduced both the intrarenal urea gradient and the uphill urinary-papillary gradient. In contrast, cyanide, an inhibitor of oxidative metabolism, had no observable effect on the urea gradients. The data are best explained by postulating an active transport system for urea in the medullary collecting duct deriving its energy from anaerobic glycolysis.

Effect of various inhibitors on several enzymes and other biochemical substances in chick embryo explants

ABSTRACT Earlier studies in our laboratory indicated the predominance of pentose cycle activity in early embryos (Jolley, Cheldelin & Newburgh, 1959; Coffey, 1963). In addition a correlation was demonstrated between enzymes generating reduced triphosphopyridine nucleotide and lipid synthesis (Bieber, Cheldelin & Newburgh, 1962; Baker & Newburgh, 1963). Since several of the biosynthetic pathways involve this compound, it is conceivable that in a rapidly growing system such as the early chick embryo enzymes generating TPNH may play a major röle. We have chosen to use explants of chick embryos in an attempt to gain insight into the relation of changes of these enzymes with other chemical changes which may more directly relate to differentiation. These latter changes include synthesis of such macromolecules as DNA, RNA, hemoglobin, collagen and myosin. This method permits the addition of certain chemicals to the media such as substrates or inhibitors (Hayashi et al., 1959), allowing easy manipulation of the environment. Prior to studying the above macromolecules it seemed appropriate to study the effect of certain inhibitors on glucose-6-phosphate, 6-phosphogluconic acid and isocitric dehydrogenase. It was hoped that such information might be useful for purposes of establishing base lines of biochemical activity. The inhibitors chosen were fluorouracil, chloramphenicol and acetyl pyridine, and it will be shown that these had several rather specific effects on the enzymes studied. The first two inhibitors were chosen because of their relation to RNA or protein biosynthesis and the latter since it is an analogue of the pyridine moiety of TPN.

Briefs - "Kinetics of the Copper-Ferric Chloride Reaction and the Effects of Certain Inhibitors"

Briefs - "Kinetics of the Copper-Ferric Chloride Reaction and the Effects of Certain Inhibitors"