scholarly journals Metabolism of an Alkyl Polyamine Analog by a Polyamine Oxidase from the Microsporidian Encephalitozoon cuniculi

2009 ◽  
Vol 53 (6) ◽  
pp. 2599-2604 ◽  
Author(s):  
Cyrus J. Bacchi ◽  
Nigel Yarlett ◽  
Evangeline Faciane ◽  
Xiangdong Bi ◽  
Donna Rattendi ◽  
...  
Keyword(s):  
Oxidase Activity ◽  
Competitive Inhibition ◽  
Amine Oxidase ◽  
Reaction Rates ◽  
Competitive Inhibitor ◽  
Host Cells ◽  
Nuclear Magnetic Resonance Analysis ◽  
Encephalitozoon Cuniculi ◽  
Resonance Analysis ◽  
Polyamine Analog

ABSTRACT Encephalitozoon cuniculi is a microsporidium responsible for systemic illness in mammals. In the course of developing leads to new therapy for microsporidiosis, we found that a bis(phenylbenzyl)3-7-3 analog of spermine, 1,15-bis{N-[o-(phenyl)benzylamino}-4,12-diazapentadecane (BW-1), was a substrate for an E. cuniculi amine oxidase activity. The primary natural substrate for this oxidase activity was N′-acetylspermine, but BW-1 had activity comparable to that of the substrate. As the sole substrate, BW-1 gave linear reaction rates over 15 min and K m of 2 μM. In the presence of N′-acetylspermine, BW-1 acted as a competitive inhibitor of oxidase activity and may be a subversive substrate, resulting in increased peroxide production. By use of 13C-labeled BW-1 as a substrate and nuclear magnetic resonance analysis, two products were determined to be oxidative metabolites, a hydrated aldehyde or dicarboxylate and 2(phenyl)benzylamine. These products were detected after exposure of 13C-labeled BW-1 to E. cuniculi preemergent spore preparations and to uninfected host cells. In previous studies, BW-1 was curative in a rodent model of infection with E. cuniculi. The results in this study demonstrate competitive inhibition of oxidase activity by BW-1 and support further studies of this oxidase activity by the parasite and host.

scholarly journals Mechanism of reaction of allylamine with the quinoprotein methylamine dehydrogenase

1995 ◽  
Vol 308 (2) ◽  
pp. 487-492 ◽  
Author(s):  
V L Davidson ◽  
M E Graichen ◽  
L H Jones
Keyword(s):  
Competitive Inhibition ◽  
Amine Oxidase ◽  
Kinetic Studies ◽  
Kinetic Mechanism ◽  
Competitive Inhibitor ◽  
Amine Oxidases ◽  
Methylamine Dehydrogenase ◽  
Oxidative Deamination ◽  
Tryptophan Tryptophylquinone ◽  
Mechanism Of Reaction

Allylamine did not serve as an efficient substrate for methylamine dehydrogenase (EC 1.4.99.3) in a steady-state assay of activity and appeared to act as a competitive inhibitor of methylamine oxidation by methylamine dehydrogenase. Transient kinetic studies, however, revealed that allylamine rapidly reduced the tryptophan tryptophylquinone (TTQ) cofactor of methylamine dehydrogenase. The rate of TTQ reduction by allylamine was 322 s-1, slightly faster than the rate of reduction by methylamine. These data were explained by a kinetic mechanism in which allylamine and methylamine are alternative substrates for methylamine dehydrogenase. The apparent competitive inhibition by allylamine is due to a very slow rate of release of the aldehyde product, 0.28 s-1, relative to a rate of 18.6 s-1 for the release of the aldehyde product of methylamine oxidation. A reaction mechanism is proposed for the oxidative deamination of allylamine by methylamine dehydrogenase. This mechanism is discussed in relation to the reaction mechanisms of topa-bearing quinoprotein amine oxidases, the flavoprotein monoamine oxidase and the mammalian semicarbazide-sensitive amine oxidase.

scholarly journals The bacterial Ras/Rap1 site-specific endopeptidase RRSP cleaves Ras through an atypical mechanism to disrupt Ras-ERK signaling

2018 ◽  
Vol 11 (550) ◽  
pp. eaat8335 ◽  
Author(s):  
Marco Biancucci ◽  
George Minasov ◽  
Avik Banerjee ◽  
Alfa Herrera ◽  
Patrick J. Woida ◽  
...  
Keyword(s):  
Vibrio Vulnificus ◽  
Small Gtpases ◽  
Host Cells ◽  
Nuclear Magnetic Resonance Analysis ◽  
Nucleotide Exchange ◽  
Resonance Analysis ◽  
Guanine Nucleotide Exchange ◽  
Nucleotide Exchange Factor ◽  
Ras Inhibition ◽  
Extracellular Signal

The Ras–extracellular signal–regulated kinase pathway is critical for controlling cell proliferation, and its aberrant activation drives the growth of various cancers. Because many pathogens produce toxins that inhibit Ras activity, efforts to develop effective Ras inhibitors to treat cancer could be informed by studies of Ras inhibition by pathogens.Vibrio vulnificuscauses fatal infections in a manner that depends on multifunctional autoprocessing repeats-in-toxin, a toxin that releases bacterial effector domains into host cells. One such domain is the Ras/Rap1-specific endopeptidase (RRSP), which site-specifically cleaves the Switch I domain of the small GTPases Ras and Rap1. We solved the crystal structure of RRSP and found that its backbone shares a structural fold with the EreA/ChaN-like superfamily of enzymes. Unlike other proteases in this family, RRSP is not a metalloprotease. Through nuclear magnetic resonance analysis and nucleotide exchange assays, we determined that the processing of KRAS by RRSP did not release any fragments or cause KRAS to dissociate from its bound nucleotide but instead only locally affected its structure. However, this structural alteration of KRAS was sufficient to disable guanine nucleotide exchange factor–mediated nucleotide exchange and prevent KRAS from binding to RAF. Thus, RRSP is a bacterial effector that represents a previously unrecognized class of protease that disconnects Ras from its signaling network while inducing limited structural disturbance in its target.

scholarly journals A Functional Interaction Between the SARS-CoV-2 Spike Protein and the Human α7 Nicotinic Receptor

2021 ◽  
Author(s):  
Juan Facundo Chrestia ◽  
Ana Sofia Oliveira ◽  
Adrian J. Mulholland ◽  
Timothy Gallagher ◽  
Isabel Bermúdez ◽  
...  
Keyword(s):  
Nicotinic Acetylcholine Receptors ◽  
Competitive Inhibition ◽  
Binding Pocket ◽  
Competitive Inhibitor ◽  
Host Cells ◽  
Spike Protein ◽  
Potential Contribution ◽  
Functional Interaction ◽  
S Protein ◽  
Α7 Nachr

Abstract Coronavirus disease 2019 (COVID-19) is caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Infection relies on the binding of the viral spike protein (S) to angiotensin-converting enzyme 2 in host cells. The S protein has been suggested to interact with nicotinic acetylcholine receptors (nAChRs), and a potential contribution of nAChRs to COVID-19 pathophysiology has been proposed. α7 nAChR is an interesting candidate target since it is present in neuronal and non-neuronal cells, including immune cells, and has anti-inflammatory actions. We here identified a novel direct functional interaction between the α7 nAChR and the Y674-R685 S region. The S fragment exerts a dual effect, acting as a low-efficacy agonist and a non-competitive inhibitor. It activates the α7 nAChR, in line with our previous molecular dynamics simulations showing favorable binding of this accessible region of the S protein to the nAChR agonist binding pocket. However, activation requires the presence of positive allosteric modulators that enhance channel opening probability, indicating very low activation efficacy. The S fragment also induces an overlapped non-competitive inhibition, which may be the predominant effect on α7 responses. This study provides unequivocal evidence supporting a functional α7-S protein interaction, which opens doors for exploring the involvement of nAChRs in COVID-19 pathophysiology.

Mitochondrial Oxidation of p-N, N-Dimethylamino-β-Phenethylamine (DAPA)

1975 ◽  
Vol 33 ◽  
pp. 458-459
Author(s):  
W. Allen Shannon ◽  
Hannah L. Wasserkrug ◽  
andArnold M. Seligman
Keyword(s):  
Guinea Pig ◽  
Oxidase Activity ◽  
Amine Oxidase ◽  
Histochemical Demonstration ◽  
Guinea Pig Heart ◽  
Pig Kidney ◽  
Cytoplasmic Vacuoles ◽  
Liver And Kidney ◽  
Mitochondrial Oxidation ◽  
Amine Oxidase Activity

The synthesis of a new substrate, p-N,N-dimethylamino-β-phenethylamine (DAPA)3 (Fig. 1) (1,2), and the testing of it as a possible substrate for tissue amine oxidase activity have resulted in the ultracytochemical localization of enzyme oxidase activity referred to as DAPA oxidase (DAPAO). DAPA was designed with the goal of providing an amine that would yield on oxidation a stronger reducing aldehyde than does tryptamine in the histochemical demonstration of monoamine oxidase (MAO) with tetrazolium salts.Ultracytochemical preparations of guinea pig heart, liver and kidney and rat heart and liver were studied. Guinea pig kidney, known to exhibit high levels of MAO, appeared the most reactive of the tissues studied. DAPAO reaction product appears primarily in mitochondrial outer compartments and cristae (Figs. 2-4). Reaction product is also localized in endoplasmic reticulum, cytoplasmic vacuoles and nuclear envelopes (Figs. 2 and 3) and in the sarcoplasmic reticulum of heart.

Kinetic Aspects of the Interaction of Blood Clotting Enzymes

1968 ◽  
Vol 19 (03/04) ◽  
pp. 364-367 ◽  
Author(s):  
H. C Hemker ◽  
P. W Hemker
Keyword(s):  
Enzyme Kinetics ◽  
Blood Clotting ◽  
Competitive Inhibition ◽  
Competitive Inhibitor ◽  
Kinetics Of

SummaryThe enzyme kinetics of competitive inhibition under conditions prevailing in clotting tests are developed and a method is given to measure relative amounts of a competitive inhibitor by means of the t — D plot.

scholarly journals Tunneling Spectroscopy by Nuclear Magnetic Resonance: Analysis of Rotational Tunneling in Solid Pentamethylbenzene

1985 ◽  
Vol 40 (11) ◽  
pp. 1075-1084
Author(s):  
W. T. Sobol ◽  
K.R. Sridharan ◽  
I. G. Cameron ◽  
M. M. Pintar
Keyword(s):  
Frequency Dependence ◽  
Lattice Relaxation ◽  
Time Correlation ◽  
Lattice Relaxation Time ◽  
Polarization Transfer ◽  
Spin Lattice Relaxation ◽  
Transfer Model ◽  
Nuclear Magnetic Resonance Analysis ◽  
Spin Lattice ◽  
Resonance Analysis

The frequency dependence of the spin-lattice relaxation time T1 was measured at three temperatures near one of the Zeeman-tunneling level matching resonances for pentamethylbenzene. These measurements are correlated with 71 temperature dependence data from the literature. It is shown that the frequency dependence of the Zeeman-torsion coupling time cannot be explained in terms of the semiclassical perturbation theory using time correlation functions. A three bath polarization transfer model is also employed and the applicability of both models discussed. Zeeman-torsion coupling is further investigated using a saturation sequence and the results are compared with the predictions of the three bath polarization transfer model.

Acrolein produced from polyamines as one of the uraemic toxins

2003 ◽  
Vol 31 (2) ◽  
pp. 371-374 ◽  
Author(s):  
K. Sakata ◽  
K. Kashiwagi ◽  
S. Sharmin ◽  
S. Ueda ◽  
K. Igarashi
Keyword(s):  
Renal Failure ◽  
Chronic Renal Failure ◽  
Oxidase Activity ◽  
Culture Medium ◽  
Cellular Proliferation ◽  
Amine Oxidase ◽  
Early Stage ◽  
Chronic Glomerulonephritis ◽  
Toxic Compound ◽  
Amine Oxidase Activity

It is well known that the addition of spermine or spermidine to culture medium containing ruminant serum inhibits cellular proliferation. This effect is caused by the products of oxidation of polyamines that are generated by serum amine oxidase. Among the products, we found that acrolein is a major toxic compound produced from spermine and spermidine by amine oxidase. We then analysed the level of polyamines (putrescine, spermidine and spermine) and amine oxidase activity in plasma of patients with chronic renal failure. It was found that the levels of putrescine and the amine oxidase activity were increased, whereas spermidine and spermine were decreased in plasma of patients with chronic renal failure. The levels of free and protein-conjugated acrolein were also increased in plasma of patients with chronic renal failure. An increase in putrescine, amine oxidase and acrolein in plasma was observed in all cases such as diabetic nephropathy, chronic glomerulonephritis and nephrosclerosis. These results suggest that acrolein is produced during the early stage of nephritis through kidney damage and also during uraemia through accumulation of polyamines in blood due to the decrease in their excretion into urine.

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