Effect of hydroxamic acids on growth and urease activity in Corynebacterium renale

1976 ◽  
Vol 22 (4) ◽  
pp. 544-551 ◽  
Author(s):  
Robert M. Nervig ◽  
Solomon Kadis
Keyword(s):  
Urease Activity ◽  
Hydroxamic Acids ◽  
Terminal Group ◽  
Side Chain ◽  
Acetohydroxamic Acid ◽  
Maximal Growth ◽  
Maximal Inhibition ◽  
Intact Cells ◽  
Lag Period ◽  
The Common

Studies were conducted on the effect of four different hydroxamic acids (HA), hydroxyurea, acetohydroxamic acid, p-fluorobenzoylhydroxamic acid and sorbylhydroxamic acid, on the growth and urease activity of Corynebacterium renale. The addition of each of these HA, at concentrations ranging from 10−3 to 10−5 M, to medium containing urea as the sole nitrogen source resulted in a lengthened lag period of growth the extent of which depended upon the concentration of each HA tested as well as the structure of the compound; that is, the size and (or) complexity of the side chain attached to the common terminal group of the molecule. However, the maximal growth levels achieved following conclusion of the exponential phase were not affected by the HA. Investigations on the effect of these HA on the urease activity of intact cells as well as cell-free extracts revealed that in each case the enzymatic activity was inhibited by each of the HA tested. The extent of inhibition with the intact cells was about one-half of that observed with cell-free extracts. Direct incubation of cell-free extracts as well as intact cells with each of the HA tested was required for maximal inhibition.

scholarly journals Plakinamine P, A Steroidal Alkaloid with Bactericidal Activity against Mycobacterium tuberculosis

Marine Drugs ◽  
2019 ◽  
Vol 17 (12) ◽  
pp. 707 ◽  
Author(s):  
Carolina Rodrigues Felix ◽  
Jill C. Roberts ◽  
Priscilla L. Winder ◽  
Rashmi Gupta ◽  
M. Cristina Diaz ◽  
...  
Keyword(s):  
Axial Position ◽  
Side Chain ◽  
Moderate Activity ◽  
Steroidal Alkaloid ◽  
Magnetic Resonance Data ◽  
Resonance Data ◽  
Low Toxicity ◽  
The Common ◽  
Future Work ◽  
Discovery Pipeline

Tuberculosis is the leading cause of death due to infectious disease worldwide. There is an urgent need for more effective compounds against this pathogen to control the disease. Investigation of the anti-mycobacterial activity of a deep-water sponge of the genus Plakina revealed the presence of a new steroidal alkaloid of the plakinamine class, which we have given the common name plakinamine P. Its structure is most similar to plakinamine L, which also has an acyclic side chain. Careful dissection of the nuclear magnetic resonance data, collected in multiple solvents, suggests that the dimethyl amino group at the 3 position is in an equatorial rather than axial position unlike previously reported plakinamines. Plakinamine P was bactericidal against M. tuberculosis, and exhibited moderate activity against other mycobacterial pathogens, such as M. abscessus and M. avium. Furthermore, it had low toxicity against J774 macrophages, yielding a selectivity index (SI, or IC50/MIC) of 8.4. In conclusion, this work provides a promising scaffold to the tuberculosis drug discovery pipeline. Future work to determine the molecular target of this compound may reveal a pathway essential for M. tuberculosis survival during infection.

Gut-brain signaling of water absorption inhibits vasopressin in rats

1995 ◽  
Vol 268 (1) ◽  
pp. R236-R247 ◽  
Author(s):  
A. J. Baertschi ◽  
R. A. Pence
Keyword(s):  
Heart Rate ◽  
Water Absorption ◽  
Hypertonic Saline ◽  
Maximal Inhibition ◽  
Water Infusion ◽  
Vagal Nerves ◽  
Dependent Inhibition ◽  
Cervical Vagotomy ◽  
The Common ◽  
Highly Correlated

The mechanism for inhibition of vasopressin (AVP) by gastric water infusion was examined in 24- or 48-h dehydrated conscious rats (n = 136 rats, 255 experiments; mean AVP baseline = 6.3 pg/ml). Gastric water infusions of 1 (n = 8), 2.5 (n = 19), and 4 ml (n = 10) caused a volume-dependent inhibition of plasma AVP by -0.31, -1.77*, and -3.02* pg/ml, with decreases of systemic osmolality of -1.06, -1.52, and -4.26* mosmol/kgH2O (* = significant vs. isotonic, Duncan's test). Gastric isotonic infusions (1-4 ml) had no effect or slightly increased AVP. Systemic infusions of 1.25 (n = 6), 2.1 (n = 10), and 6.3 ml (n = 8) inhibited AVP by -0.48, -1.07, and -2.51 pg/ml, with decreases in systemic osmolality of -1.61, -2.77*, and -7.21* mosmol/kgH2O. Systemic isotonic infusions (2.1 and 6.3 ml) slightly inhibited AVP by -0.71 and -0.85 pg/ml. Individual changes in AVP by gastric infusion of 2.5 ml of water did not correlate with changes in systemic osmolality, mean arterial pressure, or heart rate but highly correlated with preinfusion AVP (r = 0.74, P < 0.0001, n = 28). Pretreatment with systemic atropine methyl bromate (0.7 mg/rat), which abolishes the AVP secretion to gastric hypertonic saline, did not affect the AVP response to gastric water infusion (n = 9). Combination of 2.5 ml of gastric water and systemic hypertonic saline prevented the decrease in systemic osmolality and still significantly inhibited plasma AVP. Maximal inhibition of AVP by gastric water was reduced by 62.6% after lesion of the common hepatic vagal branch (n = 5) relative to shams with identical abdominal surgery (n = 6) and by 62.7 and 72.5% after right (n = 11) and left (n = 8) cervical vagotomy relative to 12 shams (P < 0.05). The results show that 1) gastric water absorption is signaled mainly by splanchnic osmosensors, 2) water signaling is atropine insensitive, and 3) the major water-signaling pathway projects through the common hepatic vagal branch and cervical vagal nerves.

scholarly journals Methods for the aquarium maintenance of the common octopus of British waters, Eledone cirrhosa

1981 ◽  
Vol 15 (4) ◽  
pp. 327-331 ◽  
Author(s):  
P. R. Boyle
Keyword(s):  
Sexual Maturation ◽  
Growth Rates ◽  
Specific Growth ◽  
Mean Annual Temperature ◽  
Maximal Growth ◽  
Endogenous Factors ◽  
Wet Weight ◽  
The Common ◽  
Common Octopus ◽  
Specific Growth Rates

Healthy, undamaged specimens survive well in recirculating aquarium seawater of about 36 parts per thousand salinity and pH 7·4, having 50 mg.l-1 nitrogen as nitrate, < 0·1 mg.l-1 nitrogen as nitrite, and < 0·1 mg.l-1 nitrogen as ammonia, and a mean annual temperature of 14-15°C, about 5°C above ambient. For maximal growth rates, the gross wet weight of live crabs required as food ranges up to 10% of the weight of the octopus. Weight-specific growth rates fall from 3-4% day-1 at 100-200 g bodyweight, to 1-1°5% day-1 at >500 g bodyweight. Survival of healthy, wild-caught animals, commonly 4-6 months and up to 8 months, is apparently limited more by endogenous factors concerned with sexual maturation and lifespan than by aquarium conditions. Eggs have been laid but it has not yet been possible to hatch and rear them.

scholarly journals Rapid electrogenic sulfate-chloride exchange mediated by chemically modified band 3 in human erythrocytes.

1995 ◽  
Vol 105 (1) ◽  
pp. 21-47 ◽  
Author(s):  
M L Jennings
Keyword(s):  
Negative Charge ◽  
Exchange Process ◽  
Band 3 ◽  
Side Chain ◽  
Intact Cells ◽  
Translocation Event ◽  
Cation Permeability ◽  
Woodward’S Reagent K ◽  
Chloride Exchange ◽  
Net Positive Charge

One of the modes of action of the red blood cell anion transport protein is the electrically silent net exchange of 1 Cl- for 1 SO4= and 1 H+. Net SO4(=)-Cl- exchange is accelerated by low pH or by conversion of the side chain of glutamate 681 into an alcohol by treatment of intact cells with Woodward's reagent K (WRK) and BH4-. The studies described here were performed to characterize the electrical properties of net SO4(=)-Cl- exchange in cells modified with WRK/BH4-. The SO4= conductance measured in 100 mM SO4= medium is smaller in modified cells than in control cells. However, the efflux of [35S] SO4= into a 150-mM KCl medium is 80-fold larger in modified cells than in control cells and is inhibited 99% by 10 microM H2DIDS. No detectable H+ flux is associated with SO4(=)-Cl- exchange in modified cells. In the presence of gramicidin to increase the cation permeability, the stoichiometry of SO4(=)-Cl- exchange is not distinguishable from 1:1. In modified cells loaded with SO4=, the valinomycin-mediated efflux of 86Rb+ into an Na-gluconate medium is immediately stimulated by the addition of 5 mM extracellular Cl-. Therefore, SO4(=)-Cl- exchange in modified cells causes an outward movement of negative charge, as expected for an obligatory 1:1 SO4(=)-Cl- exchange. This is the first example of an obligatory, electrogenic exchange process in band 3 and demonstrates that the coupling between influx and efflux does not require that the overall exchange be electrically neutral. The effects of membrane potential on SO4(=)-SO4= exchange and SO4(=)-Cl- exchange in modified cells are consistent with a model in which nearly a full net positive charge moves inward through the transmembrane field during the inward Cl- translocation event, and a small net negative charge moves with SO4= during the SO4= translocation event. This result suggests that, in normal cells, the negative charge on Glu 681 traverses most of the transmembrane electric field, accompanied by Cl- and the equivalent of two protein-bound positive charges.

Inhibition of Urease Activity by Dipeptidyl Hydroxamic Acids.

1992 ◽  
Vol 40 (10) ◽  
pp. 2764-2768 ◽  
Author(s):  
Shinjiro ODAKE ◽  
Kazuaki NAKAHASHI ◽  
Tadanori MORIKAWA ◽  
Sachiko TAKEBE ◽  
Kyoichi KOBASHI
Keyword(s):  
Urease Activity ◽  
Hydroxamic Acids

scholarly journals Acylation of carcinogenic hydroxamic acids by carbamoyl phosphate to form reactive esters

1971 ◽  
Vol 124 (1) ◽  
pp. 69-74 ◽  
Author(s):  
P D. Lotlikar ◽  
L Luha
Keyword(s):  
Hydroxamic Acids ◽  
Phosphate Concentration ◽  
Acetyl Phosphate ◽  
Acylating Agent ◽  
Carbamoyl Phosphate ◽  
Acetyl Coa ◽  
Ph Optimum ◽  
Lag Period ◽  
Reactive N ◽  
Derivatives Of

1. Acylation of 2-(N-hydroxyacetamido)fluorene and several other aromatic hydroxamic acids by carbamoyl phosphate was studied and compared with the acylating activity of acetyl-CoA. Acetyl phosphate was also studied. 2. The carbamoylation reaction had a pH optimum of 4.5. The reaction had a lag period of 1h and was then linear for 4h. This linearity ranged between 0.5mm- and 8mm-carbamoyl phosphate concentration. 3. At pH7.5, acetyl-CoA was the most powerful acylating agent. Acetyl phosphate was a weaker acylating agent than either of the others. 4. Among the various hydroxamic acids tested with acetyl-CoA and carbamoyl phosphate at pH.7.5, 2-(N-hydroxyacetamido)fluorene was the most reactive. On the other hand the less reactive N-hydroxy derivatives of 2-acetamidonaphthalene, 2-acetamidophenanthrene and 4-acetamidostilbene reacted severalfold more with carbamoyl phosphate than with acetyl-CoA. 5. It is suggested that carbamoylation of aromatic hydroxamic acids might be one of the final activation steps in carcinogenesis by these compounds.

Influence of the terminal group on optoelectronic properties of fused-ring nonfullerene acceptors with ethylhexyl side chain

2021 ◽  
pp. 109635
Author(s):  
Qian Zhang ◽  
Muhammad Abdullah Adil ◽  
Zhongke Wang ◽  
Guangtao Zhao ◽  
Tao Wang ◽  
...  
Keyword(s):  
Terminal Group ◽  
Optoelectronic Properties ◽  
Side Chain ◽  
Fused Ring

scholarly journals Energetics of Helicobacter pylori and Its Implications for the Mechanism of Urease-Dependent Acid Tolerance at pH 1

2002 ◽  
Vol 184 (11) ◽  
pp. 3053-3060 ◽  
Author(s):  
Kerstin Stingl ◽  
Eva-Maria Uhlemann ◽  
Roland Schmid ◽  
Karlheinz Altendorf ◽  
Evert P. Bakker
Keyword(s):  
Helicobacter Pylori ◽  
Membrane Potential ◽  
Urease Activity ◽  
Cytoplasmic Ph ◽  
Ph Homeostasis ◽  
Intact Cells ◽  
Ph Values ◽  
Cell Extracts ◽  
H Pylori ◽  
External Ph

ABSTRACT In the presence of urea the neutrophilic human pathogen Helicobacter pylori survives for several hours at pH 1 with concomitant cytoplasmic pH homeostasis. To study this effect in detail, the transmembrane proton motive force and cytoplasmic urease activity of H. pylori were determined at various pH values. In the absence of urea, the organism maintained a close-to-neutral cytoplasm and an internally negative membrane potential at external pH values greater than 4 to 5. In the presence of urea, H. pylori accomplished cytoplasmic pH homeostasis down to an external pH of 1.2. At this external pH, the cytoplasmic pH was 4.9 and the membrane potential was slightly negative inside. The latter finding is in contrast to the situation in acidophiles, which develop inside-positive membrane potentials under similar conditions. Measurements of the time course of the membrane potential confirmed that addition of urea to the cells led to hyperpolarization. Most likely, this effect was due to electrogenic export of ammonium cations from the cytoplasm. The urease activity of intact cells increased nearly exponentially with decreasing external pH. This activation was not due to enhanced gene expression at low external pH values. In cell extracts the pH optimum of urease activity was dependent on the buffer system and was about pH 5 in sodium citrate buffer. Since this is the cytoplasmic pH of the cells at pH 1 to 2, we propose that cytoplasmic pH is a factor in the in vivo activation of the urease at low external pH values. The mechanism by which urease activity leads to cytoplasmic pH homeostasis in H. pylori is discussed.

Some aspects of neptunium acetohydroxamic acid chemistry under acidic conditions

2009 ◽  
Vol 97 (4-5) ◽  
Author(s):  
Mark J. Sarsfield ◽  
Robin J. Taylor ◽  
C. Boxall ◽  
F. Adrieux ◽  
H. E. Sims
Keyword(s):  
Hydroxamic Acids ◽  
Acetohydroxamic Acid ◽  
Acidic Conditions

AbstractHydroxamic acids are promising complexant based alternatives to the reductant (U

Sign in / Sign up

Export Citation Format

Share Document