scholarly journals Effects of proteins and polynucleotides on the activity of various hydrolases

1972 ◽  
Vol 127 (5) ◽  
pp. 795-800 ◽  
Author(s):  
M. J. Palmieri ◽  
O. Koldovský
Keyword(s):  
Specific Activity ◽  
Inhibitory Effect ◽  
Low Ph ◽  
Acid Hydrolases ◽  
Ileal Mucosa ◽  
Suckling Rats ◽  
Assay Mixture ◽  
Dependent Inhibition ◽  
Ph Dependent ◽  
The Relationship

The effect of various macromolecules on the activity of several hydrolases was studied. Dilution of partially purified acid β-galactosidase from ileal mucosa of suckling rats resulted in a decrease of specific activity. The relationship between specific activity and dilution of the enzyme suggests a dissociation of the enzyme. This could be prevented by addition of several proteins tested. However, addition of DNA to the assay mixture for acid β-galactosidase caused an inhibition. This inhibition could be prevented by addition of proteins. Other polynucleotides and tRNA also exert an inhibitory effect that is prevented by albumin, but nucleotides have no effect. This inhibition occurs maximally at a low pH (3.0–4.0); no inhibition is observed at pH5.5. A similar pH-dependent inhibition by DNA was also found with various other acid hydrolases.

scholarly journals pH-dependent inhibition by azide and fluoride of the iron superoxide dismutase from Propionibacterium shermanii

1998 ◽  
Vol 331 (2) ◽  
pp. 403-407 ◽  
Author(s):  
Beate MEIER ◽  
Christoph SCHERK ◽  
Marius SCHMIDT ◽  
Fritz PARAK
Keyword(s):  
Superoxide Dismutase ◽  
Active Site ◽  
Low Ph ◽  
Superoxide Dismutases ◽  
Iron Superoxide Dismutase ◽  
Propionibacterium Shermanii ◽  
Hydroxyl Anion ◽  
Dependent Inhibition ◽  
Ph Dependent ◽  
A Minor

The iron-containing superoxide dismutase from Propionibacterium shermanii shows, in contrast with other iron superoxide dismutases, only a minor inhibition by azide or fluoride (10–100 mM) of up to 23% at pH 7.8. The activity of the protein with Mn bound to the active site was not diminished under the same conditions. The binding constant between azide and the Fe3+ ion was determined as approx. 2 mM and for fluoride approx. 2.3 mM; they are so far comparable to those known for other iron superoxide dismutases. This seems to be a discrepancy because all other iron superoxide dismutases so far known are described as being inhibited by 50–70% by 10 mM azide. However, towards lower pH there was a drastically increased inhibition by both anions. At pH 6.8 about 80% inhibition was exhibited by azide or fluoride at a concentration of 10 mM or higher. In contrast, on increasing the pH, azide or fluoride still bound to the Fe3+ at the active site but their inhibition capacity decreased. This observation implies that both anions bind to the metal at a position that is empty at low pH, whereas at higher pH water or a negatively charged hydroxyl anion is bound. It is likely that the superoxide anion binds to the same position and has to replace the sixth ligand, leading to a diminished catalytic activity of the superoxide dismutase owing to steric and/or electrostatic inhibition of the ligand.

Effects of Aluminum and Low pH on Net Ion Fluxes and Ion Balance in the Brook Trout (Salvelinus fontinalis)

1988 ◽  
Vol 45 (9) ◽  
pp. 1563-1574 ◽  
Author(s):  
C. E. Booth ◽  
D. G. McDonald ◽  
B. P. Simons ◽  
C. M. Wood
Keyword(s):  
Brook Trout ◽  
Salvelinus Fontinalis ◽  
Inhibitory Effect ◽  
Low Ph ◽  
Exposed Fish ◽  
Water Ph ◽  
In The Wild ◽  
Ph Dependent ◽  
Total Body ◽  
Stimulation Of

Adult brook trout (Salvelinus fontinalis) were exposed for up to 11 d to one of a matrix of 18 Al, low pH, and Ca2+ combinations, chosen as representive of acidified softwater environments in the wild. Reduction in water pH led to pH-dependent net losses of Na+ and Cl− exacerbated by the presence of Al in the water and reduced by elevating Ca2+. Any animal losing more than 4% of its total body Na+ over the first 24 h of Al exposure had a greater than 90% likelihood of eventual mortality. Na+ losses arose from inhibition of influx and stimulation of efflux. The inhibition was persistent and pH dependent. Addition of Al to acidified water had a slight further inhibitory effect on Na+ influx and a large stimulatory effect on efflux. The latter was dependent on Al concentration, was the main cause of initial ion losses and mortality, and declined with time in surviving animals. All Al-exposed fish accumulated Al on their gills, but this was apparently mainly surface or subsurface bound, since no internal Al (plasma or liver) could be detected. Nonsurviving fish had substantially higher gill Al levels than survivors.

scholarly journals microRNA-96 promotes occurrence and progression of colorectal cancer via regulation of the AMPKα2-FTO-m6A/MYC axis

2020 ◽  
Vol 39 (1) ◽  
Author(s):  
Caifeng Yue ◽  
Jierong Chen ◽  
Ziyue Li ◽  
Laisheng Li ◽  
Jugao Chen ◽  
...  
Keyword(s):  
Colorectal Cancer ◽  
Growth Cycle ◽  
Inhibitory Effect ◽  
Luciferase Reporter ◽  
Loss Of Function ◽  
Cycle Progression ◽  
Dependent Inhibition ◽  
The Relationship ◽  
Dual Luciferase Reporter Assay

Abstract Background Colorectal cancer (CRC) is one of the frequently occurred malignancies in the world. To date, several onco-microRNAs (miRNAs or miRs), including miR-96, have been identified in the pathogenesis of CRC. In the present study, we aimed to corroborate the oncogenic effect of miR-96 on CRC and to identify the specific mechanisms related to AMPKα2/FTO/m6A/MYC. Methods RT-qPCR and Western blot analysis were performed to examine the expression pattern of miR-96, AMPKα2, FTO and MYC in the clinical CRC tissues and cells. The relationship between miR-96 and AMPKα2 was then predicted using in silico analysis and identified by dual-luciferase reporter assay. Gain- or loss-of-function approaches were manipulated to evaluate the modulatory effects of miR-96, AMPKα2, FTO and MYC on cell growth, cycle progression and apoptosis. The mechanism of FTO-mediated m6A modification of MYC was analyzed via Me-RIP and PAR-CLIP analysis. The mediatory effects of miR-96 antagomir on cancerogenesis were validated in vivo. Results miR-96, FTO and MYC were upregulated, while AMPKα2 was downregulated in CRC tissues and cells. miR-96 could down-regulate AMPKα2, which led to increased expression of FTO and subsequent upregulated expression of MYC via blocking its m6A modification. This mechanism was involved in the pro-proliferative and anti-apoptotic roles of miR-96 in CRC cells. Besides, down-regulation of miR-96 exerted inhibitory effect on tumor growth in vivo. Conclusions Taken together, miR-96 antagomir could potentially retard the cancerogenesis in CRC via AMPKα2-dependent inhibition of FTO and blocking FTO-mediated m6A modification of MYC, highlighting novel mechanisms associated with colorectal cancerogenesis.

Effects of Variations in pH and Hypothiocyanite Concentrations on S. mutans Glucose Metabolism

1987 ◽  
Vol 66 (2) ◽  
pp. 486-491 ◽  
Author(s):  
B. Mansson-Rahemtulla ◽  
D.C. Baldone ◽  
K.M. Pruitt ◽  
F. Rahemtulla
Keyword(s):  
Glucose Metabolism ◽  
Glucose Uptake ◽  
Streptococcus Mutans ◽  
Low Ph ◽  
Oral Streptococci ◽  
Positive Correlation ◽  
Ph Changes ◽  
Glucose Incorporation ◽  
Dependent Inhibition ◽  
Ph Dependent

Hypothiocyanous acid (HOSCN) and hypothiocyanite (OSCN-) were generated by the antibody-independent salivary peroxidase (SP) system. The metabolism of Streptococcus mutans NCTC 10449 was examined by uniformly labeled glucose incorporation studies. We found that the SP-system causes a pH-dependent inhibition of 14C-labeled glucose uptake, and that the effects of HOSCN/OSCN- are bacteriostatic. The results also showed that, at low pH, bacteria required more time to recover fully from HOSCN/OSCN- inhibition. When control experiments were performed in the absence of HOSCN/OSCN-, but the pH was varied, we found a positive correlation between pH and the rate of 14C-glucose incorporation. The results also showed that pH did not affect the maximum incorporation of 14C-glucose, demonstrating that S. mutans can adapt to pH changes in the environment. Based on the data obtained, we postulate that the antibody-independent SP system plays an important role in the regulation of the metabolism of oral streptococci.

scholarly journals Mitotic spindle function in Saccharomyces cerevisiae requires a balance between different types of kinesin-related motors.

1997 ◽  
Vol 8 (6) ◽  
pp. 1025-1033 ◽  
Author(s):  
W Saunders ◽  
V Lengyel ◽  
M A Hoyt
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Inhibitory Effect ◽  
Relative Activity ◽  
Spindle Poles ◽  
Direct Demonstration ◽  
Gal1 Promoter ◽  
Dependent Inhibition ◽  
Spindle Elongation ◽  
Spindle Function ◽  
The Relationship

Two Saccharomyces cerevisiae kinesin-related motors, Cin8p and Kip1p, perform an essential role in the separation of spindle poles during spindle assembly and a major role in spindle elongation. Cin8p and Kip1p are also required to prevent an inward spindle collapse prior to anaphase. A third kinesin-related motor, Kar3p, may act antagonistically to Cin8p and Kip1p since loss of Kar3p partially suppresses the spindle collapse in cin8 kip1 mutants. We have tested the relationship between Cin8p and Kar3p by overexpressing both motors using the inducible GAL1 promoter. Overexpression of KAR3 results in a shrinkage of spindle size and a temperature-dependent inhibition of the growth of wild-type cells. Excess Kar3p has a stronger inhibitory effect on the growth of cin8 kip1 mutants and can completely block anaphase spindle elongation in these cells. In contrast, overexpression of CIN8 leads to premature spindle elongation in all cells tested. This is the first direct demonstration of antagonistic motors acting on the intact spindle and suggests that spindle length is determined by the relative activity of Kar3p-like and Cin8p/Kip1p-like motors.

Inhibition of the Activities of α2-Plasmin inhibitor (PI) and CI inhibitor (CI-Inh) by the Synthetic Fibrinolytic Agent, 3-Hydroxypropyl Flufenamide (Flu-HPA)

1979 ◽  
Author(s):  
L Miles ◽  
J Burnier ◽  
M Verlander ◽  
M Goodman ◽  
A Kleiss ◽  
...  
Keyword(s):  
Plasminogen Activators ◽  
Inhibitory Effect ◽  
Mechanisms Of Action ◽  
Flufenamic Acid ◽  
Clot Lysis ◽  
Factor Xiia ◽  
Dependent Inhibition ◽  
Normal Human ◽  
Plasmin Inhibitor

Flu-HPA is one of a series of flufenamic acid derivations that enhances plasminogen-dependent clot lysis in vitro. Studies of possible mechanisms of action of Flu-HPA were undertaken. The influence of Flu-HPA on the inhibition of purified plasmin by purified PI was studied. PI activity was assessed by its inhibition of the clevage of the tripeptide S-2251 (H-D-Val-Leu-Lys-pNA) by plasmin. Flu-HPA was dissolved in DMF or in methonol and preincubated with PI before addition of plasmin. At Flu-HPA concentrations greater than 1mM and up to 60mM, the inhibitory activity of PI was totally lost. The inhibitory effect of normal human plasma on plasmin was also completely abolished at concentrations of Flu-HPA between 2.5 and 40mM. The effect of Flu-HPA on the inhibition of purified plasma kallikrein by purified CI-Inh was also studied. CI-Inh activity was measured by its inhibition of cleavage of the tripeptide Bz-Pro-Phe-Arg-pNA by kallikrein. When Flu-HPA, dissolved in DMF or in methonol, was preincubated with CI-Inh, a concentration dependent inhibition of CI-Inh activity was observed. CI-Inh activity was abolished by concentrations of Flu-HPA greater than 1mM. Flu-HPA also inhibited the activity of CI-Inh on purified Factor XIIa. These observations suggest that this flufenamic acid derivative may enhance fibrinolysis not only by inhibiting PI activity but also by decreasing the inactivation of plasminogen activators by CI-Inh.

scholarly journals The inhibitory effect of melatonin on human prostate cancer

2021 ◽  
Vol 19 (1) ◽  
Author(s):  
Dexin Shen ◽  
Lingao Ju ◽  
Fenfang Zhou ◽  
Mengxue Yu ◽  
Haoli Ma ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
Clinical Trials ◽  
Theoretical Basis ◽  
Inhibitory Effect ◽  
Human Prostate ◽  
Human Prostate Cancer ◽  
Anti Oxidant ◽  
Androgen Depletion ◽  
The Relationship ◽  
Future Utilization

AbstractProstate cancer (PCa) is one of the most commonly diagnosed human cancers in males. Nearly 191,930 new cases and 33,330 new deaths of PCa are estimated in 2020. Androgen and androgen receptor pathways played essential roles in the pathogenesis of PCa. Androgen depletion therapy is the most used therapies for primary PCa patients. However, due to the high relapse and mortality of PCa, developing novel noninvasive therapies have become the focus of research. Melatonin is an indole-like neurohormone mainly produced in the human pineal gland with a prominent anti-oxidant property. The anti-tumor ability of melatonin has been substantially confirmed and several related articles have also reported the inhibitory effect of melatonin on PCa, while reviews of this inhibitory effect of melatonin on PCa in recent 10 years are absent. Therefore, we systematically discuss the relationship between melatonin disruption and the risk of PCa, the mechanism of how melatonin inhibited PCa, and the synergistic benefits of melatonin and other drugs to summarize current understandings about the function of melatonin in suppressing human prostate cancer. We also raise several unsolved issues that need to be resolved to translate currently non-clinical trials of melatonin for clinic use. We hope this literature review could provide a solid theoretical basis for the future utilization of melatonin in preventing, diagnosing and treating human prostate cancer.

scholarly journals A novel role for WAVE1 in controlling actin network growth rate and architecture

2015 ◽  
Vol 26 (3) ◽  
pp. 495-505 ◽  
Author(s):  
Meredith O. Sweeney ◽  
Agnieszka Collins ◽  
Shae B. Padrick ◽  
Bruce L. Goode
Keyword(s):  
Actin Filament ◽  
Specific Activity ◽  
Inhibitory Effect ◽  
Actin Network ◽  
Inhibitory Effects ◽  
Cellular Functions ◽  
Network Growth ◽  
Assembly Kinetics ◽  
Filament Networks ◽  
First Time

Branched actin filament networks in cells are assembled through the combined activities of Arp2/3 complex and different WASP/WAVE proteins. Here we used TIRF and electron microscopy to directly compare for the first time the assembly kinetics and architectures of actin filament networks produced by Arp2/3 complex and dimerized VCA regions of WAVE1, WAVE2, or N-WASP. WAVE1 produced strikingly different networks from WAVE2 or N-WASP, which comprised unexpectedly short filaments. Further analysis showed that the WAVE1-specific activity stemmed from an inhibitory effect on filament elongation both in the presence and absence of Arp2/3 complex, which was observed even at low stoichiometries of WAVE1 to actin monomers, precluding an effect from monomer sequestration. Using a series of VCA chimeras, we mapped the elongation inhibitory effects of WAVE1 to its WH2 (“V”) domain. Further, mutating a single conserved lysine residue potently disrupted WAVE1's inhibitory effects. Taken together, our results show that WAVE1 has unique activities independent of Arp2/3 complex that can govern both the growth rates and architectures of actin filament networks. Such activities may underlie previously observed differences between the cellular functions of WAVE1 and WAVE2.

scholarly journals Functional Entry of Baculovirus into Insect and Mammalian Cells Is Dependent on Clathrin-Mediated Endocytosis

2006 ◽  
Vol 80 (17) ◽  
pp. 8830-8833 ◽  
Author(s):  
Gang Long ◽  
Xiaoyu Pan ◽  
Richard Kormelink ◽  
Just M. Vlak
Keyword(s):  
Electron Microscopy ◽  
Mammalian Cells ◽  
Low Ph ◽  
Coated Pits ◽  
Immuno Electron Microscopy ◽  
Endocytosis Pathway ◽  
Ph Dependent ◽  
Budded Virus

ABSTRACT Entry of the budded virus form of baculoviruses into insect and mammalian cells is generally thought to occur through a low-pH-dependent endocytosis pathway, possibly through clathrin-coated pits. This insight is primarily based on (immuno)electron microscopy studies but requires biochemical support to exclude the use of other pathways. Here, we demonstrate using various inhibitors that functional entry of baculoviruses into insect and mammalian cells is primarily dependent on clathrin-mediated endocytosis. Our results further suggest that caveolae are somehow involved in baculovirus entry in mammalian cells. A caveolar endocytosis inhibitor, genistein, enhances baculovirus transduction in these cells considerably.

scholarly journals Characterization of the inositol 1,4,5-trisphosphate-induced calcium release from permeabilized endocrine cells and its inhibition by decavanadate and p-hydroxymercuribenzoate

1989 ◽  
Vol 262 (1) ◽  
pp. 83-89 ◽  
Author(s):  
K J Föhr ◽  
J Scott ◽  
G Ahnert-Hilger ◽  
M Gratzl
Keyword(s):  
Endocrine Cells ◽  
Calcium Release ◽  
Cell Types ◽  
Inhibitory Effect ◽  
Maximal Effect ◽  
Thiol Compounds ◽  
Inositol 1,4,5 Trisphosphate ◽  
Dependent Inhibition ◽  
Pheochromocytoma Pc12 ◽  
First Time

The inositol 1,4,5-trisphosphate (IP3)-sensitive Ca2+ compartment of endocrine cells was studied with alpha-toxin- and digitonin-permeabilized rat insulinoma (RINA2) and rat pheochromocytoma (PC12) cells. The Ca2+ uptake was ATP-dependent, and submicromolar concentrations of IP3 specifically released the stored Ca2+. Half-maximal Ca2+ release was observed with 0.25-0.5 mumol of IP3/l, and the amount of Ca2+ released due to IP3 could be enhanced by additional loading of the Ca2+ compartment. Consecutive additions of the same concentration of IP3 for 1-2 h always released the same amount of Ca2+ without desensitization, providing an ideal basis to further characterize the IP3-induced Ca2+ release. Here we describe for the first time a reversible inhibitory effect of decavanadate on the IP3-induced Ca2+ release. Among the vanadium species tested (decavanadate, oligovanadate and monovanadate), only decavanadate was inhibitory, with a half-maximal effect at 5 mumol/l in both cell types. The effect of decavanadate could be overcome by increasing the amount of sequestered Ca2+ or added IP3. Decavanadate did not affect the ATP-driven Ca2+ uptake but oligovanadate was inhibitory on Ca2+ uptake. p-Hydroxymercuribenzoate (pHMB) at concentrations between 10 and 30 mumol/l also inhibited the Ca2+ release due to IP3. Thiol compounds such as dithiothreitol (DTT; 1 mmol/l) added before pHMB removed all its inhibitory effect on the IP3-induced Ca2+ release, whereas the inhibition caused by decavanadate was unaffected by DTT. Thus, the decavanadate-dependent inhibition functions by a distinctly different mechanism than pHMB and could serve as a specific tool to analyse various aspects of the IP3-induced Ca2+ release within endocrine cells.

Sign in / Sign up

Export Citation Format

Share Document