Evidence that a deferrioxamine B degrading enzyme is a serine protease

1998 ◽  
Vol 44 (6) ◽  
pp. 521-527 ◽  
Author(s):  
Ninef Zaya ◽  
Alexandra Roginsky ◽  
Jamila Williams ◽  
Domenic Castignetti
Keyword(s):  
Catalytic Activity ◽  
Serine Protease ◽  
Calcium Ions ◽  
Ferric Ion ◽  
Plant Interactions ◽  
Degrading Enzyme ◽  
Carbon And Nitrogen ◽  
Serine Peptidase ◽  
Deferrioxamine B ◽  
Low Concentrations

Siderophores are organic biomolecules synthesized by a wide variety of microbes. The molecules sequester ferric ion from environments where it is present at extremely low concentrations. Siderophores are of consequence with respect to microbial nutrition, pathogenicity, virulence, and microbe-plant interactions. How siderophores are degraded and returned to the carbon and nitrogen cycles is not well understood. The catalytic activity of an enzyme from a bacterium that degrades the siderophore deferrioxamine B has been examined. While the degradation of deferrioxamine B is sensitive to sulfhydryl and metal moiety inhibitors, the data presented is most consistent with the hypothesis that the enzyme uses a hydroxyl moiety (serine peptidase) to catalyze the degradation of deferrioxamine B. If sulfhydryl and metal inhibitors are simultaneously present at concentrations that when alone only partially inhibit the enzyme, the enzyme is unable to catalyze deferrioxamine B dissimilation. Analysis of the inhibitor experiments conducted led to the conclusion that the deferrioxamine B degrading enzyme is a serine-peptidase-like enzyme that needs calcium ions and sulfhydryl groups to be fully activated or stabilized. The knowledge of the catalytic moieties of the enzyme will be exploited to purify the enzyme.Key words: siderophores, deferrioxamine B, siderophore degradation.

scholarly journals Degradation Pathway and Generation of Monohydroxamic Acids from the Trihydroxamate Siderophore Deferrioxamine B

2004 ◽  
Vol 70 (2) ◽  
pp. 831-836 ◽  
Author(s):  
Agnes Pierwola ◽  
Tomasz Krupinski ◽  
Peter Zalupski ◽  
Michael Chiarelli ◽  
Domenic Castignetti
Keyword(s):  
High Performance Liquid Chromatography ◽  
Liquid Chromatography ◽  
High Performance ◽  
Degradation Pathway ◽  
Ferric Ion ◽  
Mesorhizobium Loti ◽  
Enzyme Preparations ◽  
Carbon And Nitrogen ◽  
Deferrioxamine B ◽  
Hydroxamate Siderophores

ABSTRACT Siderophores are avid ferric ion-chelating molecules that sequester the metal for microbes. Microbes elicit siderophores in numerous and different environments, but the means by which these molecules reenter the carbon and nitrogen cycles is poorly understood. The metabolism of the trihydroxamic acid siderophore deferrioxamine B by a Mesorhizobium loti isolated from soil was investigated. Specifically, the pathway by which the compound is cleaved into its constituent monohydroxamates was examined. High-performance liquid chromatography and mass-spectroscopy analyses demonstrated that M. loti enzyme preparations degraded deferrioxamine B, yielding a mass-to-charge (m/z) 361 dihydroxamic acid intermediate and an m/z 219 monohydroxamate. The dihydroxamic acid was further degraded to yield a second molecule of the m/z 219 monohydroxamate as well as an m/z 161 monohydroxamate. These studies indicate that the dissimilation of deferrioxamine B by M. loti proceeds by a specific, achiral degradation and likely represents the reversal by which hydroxamate siderophores are thought to be synthesized.

Study of nickel-molybdenum catalysts for methanation of carbon monoxide

1980 ◽  
Vol 45 (3) ◽  
pp. 783-790 ◽  
Author(s):  
Petr Taras ◽  
Milan Pospíšil
Keyword(s):  
Carbon Monoxide ◽  
Catalytic Activity ◽  
Mixed Oxides ◽  
Minor Component ◽  
Fast Neutrons ◽  
Scanning Calorimetry ◽  
Low Concentrations ◽  
Γ Rays ◽  
Molybdenum Catalysts ◽  
Kinetics Of

Catalytic activity of nickel-molybdenum catalysts for methanation of carbon monoxide and hydrogen was studied by means of differential scanning calorimetry. The activity of NiMoOx systems exceeds that of carrier-free nickel if x < 2, and is conditioned by the oxidation degree of molybdenum, changing in dependence on the composition in the region Mo-MoO2. The activity of the catalysts is adversely affected by irradiation by fast neutrons, dose 28.1 Gy, or by γ rays using doses in the region 0.8-52 kGy. The system is most susceptible to irradiation in the region of low concentrations of the minor component (about 1 mol.%). The dependence of changes in catalytic activity of γ-irradiated samples on the dose exhibits a maximum in the range of 2-5 kGy. The changes in catalytic activity are stimulated by the change of reactivity of the starting mixed oxides, leading to different kinetics of their reduction and modification of their adsorption properties. The irradiation of the catalysts results in lowered concentration of the active centres for the methanation reaction.

scholarly journals Mirolase, a novel subtilisin-like serine protease from the periodontopathogen Tannerella forsythia

2015 ◽  
Vol 396 (3) ◽  
pp. 261-275 ◽  
Author(s):  
Miroslaw Ksiazek ◽  
Abdulkarim Y. Karim ◽  
Danuta Bryzek ◽  
Jan J. Enghild ◽  
Ida B. Thøgersen ◽  
...  
Keyword(s):  
Serine Protease ◽  
Calcium Ions ◽  
Enzyme Stability ◽  
Amidolytic Activity ◽  
Tannerella Forsythia ◽  
Calcium Dependent ◽  
Genes Encoding ◽  
Mature Enzyme ◽  
Almost All ◽  
Unique Mechanism

Abstract The genome of Tannerella forsythia, an etiological factor of chronic periodontitis, contains several genes encoding putative proteases. Here, we characterized a subtilisin-like serine protease of T. forsythia referred to as mirolase. Recombinant full-length latent promirolase [85 kDa, without its signal peptide (SP)] processed itself through sequential autoproteolytic cleavages into a mature enzyme of 40 kDa. Mirolase latency was driven by the N-terminal prodomain (NTP). In stark contrast to almost all known subtilases, the cleaved NTP remained non-covalently associated with mirolase, inhibiting its proteolytic, but not amidolytic, activity. Full activity was observed only after the NTP was gradually, and fully, degraded. Both activity and processing was absolutely dependent on calcium ions, which were also essential for enzyme stability. As a consequence, both serine protease inhibitors and calcium ions chelators inhibited mirolase activity. Activity assays using an array of chromogenic substrates revealed that mirolase specificity is driven not only by the substrate-binding subsite S1, but also by other subsites. Taken together, mirolase is a calcium-dependent serine protease of the S8 family with the unique mechanism of activation that may contribute to T. forsythia pathogenicity by degradation of fibrinogen, hemoglobin, and the antimicrobial peptide LL-37.

Engineering of serine protease for improved thermostability and catalytic activity using rational design

2019 ◽  
Vol 126 ◽  
pp. 229-237 ◽  
Author(s):  
Naeem Mahmood Ashraf ◽  
Akshaya Krishnagopal ◽  
Aadil Hussain ◽  
David Kastner ◽  
Ahmed Mahmoud Mohammed Sayed ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Serine Protease ◽  
Rational Design

scholarly journals Carbon-driven eco-agriculture without nitrogen deficiency

2013 ◽  
Author(s):  
Masato Oda ◽  
Kenji Tamura ◽  
Hiroko Nakatsuka ◽  
Miki Nakata ◽  
Yukimi Hayashi
Keyword(s):  
Organic Material ◽  
Soil Aggregates ◽  
C:N Ratio ◽  
Nitrogen Deficiency ◽  
Fertilizer Application ◽  
Carbon And Nitrogen ◽  
Large Numbers ◽  
Low Concentrations ◽  
Number Of Microorganisms ◽  
Order Of Magnitude

A farmer grew crops by adding only organic material with a high C:N ratio (40) to the soil for 30 years. He focused on the role of carbon in increasing the number of microorganisms. This idea was based on the concepts of 1) indirect crop management via microorganisms and 2) providing carbon to microorganisms for energy. Here, we name this practice “carbon -driven eco-agriculture” (CDEA). We determined the effect of CDEA on a laterite soil vegetable field in Sao Paulo for 4 years. The yield exceeded the national average. Soil aggregates formed to 29 cm thickness, and the microbial activity was one order of magnitude higher than that in a conventional control field. The output/input ratios of carbon and nitrogen were 1.88 –2.35 and 3.58–6.00, respectively, indicating a sustainable system for these elements. Incorporating high-C:N-ratio (>20) organic material results in nitrogen deficiency. However, our results indicate that large numbers of microorganisms provide crops with sufficient nitrogen at low concentrations. This method overcomes the yield limitation of chemical fertilizer application and reverses soil degradation.

The alteration of mitotic events by ionophore A23187 and carbonyl cyanide n-chlorophenylhydrazone

1985 ◽  
Vol 75 (1) ◽  
pp. 347-355
Author(s):  
M.L. Ziegler ◽  
J.E. Sisken ◽  
S. Vedbrat
Keyword(s):  
Oxidative Phosphorylation ◽  
Intracellular Calcium ◽  
Calcium Ions ◽  
Hela Cells ◽  
Cytosolic Calcium ◽  
Ionophore A23187 ◽  
Chromosome Movement ◽  
Low Concentrations ◽  
Carbonyl Cyanide ◽  
Stimulation Of

A large quantity of published work indicates that calcium ions may be involved in the regulation of mitotic events and recent reports suggest that the onset of chromosome movement is dependent upon a transient increase in free cytosolic calcium ions. In this paper we examine the effects of two agents known to perturb intracellular calcium pools on mitosis in HeLa cells. These were the calcium-selective ionophore A23187 and carbonyl cyanide n-chlorophenylhydrazone (CCCP), which is a protonophoric inhibitor of oxidative phosphorylation. Owing to a stimulation of glycolysis, the latter agent does not decrease intracellular ATP in HeLa but does cause mitochondria to release calcium ions. Our data show that, at low concentrations, both agents prolong metaphase but differ in their effects on anaphase and cytokinesis. Studies with chlorotetracycline, a commonly used probe for membrane-associated calcium, verify that these agents do affect calcium pools under the conditions of our experiments. The data presented are consistent with the idea that increased cytosolic calcium levels can directly or indirectly affect mitotic events but, contrary to other suggestions, cause a prolongation of metaphase, i.e. they delay the onset of chromosome movement.

The Role of Calcium in the Isolation of Brush Borders from Epithelial Cells of Rat Small Intestine

1966 ◽  
Vol 1 (4) ◽  
pp. 415-424
Author(s):  
P. F. MILLINGTON ◽  
D. R. CRITCHLEY ◽  
P.W. A. TOVELL
Keyword(s):  
Small Intestine ◽  
Calcium Ions ◽  
Chelating Agent ◽  
Tris Buffer ◽  
Good Separation ◽  
The Third ◽  
Low Concentrations ◽  
Brush Borders ◽  
The Stability

A chelating agent such as EDTA or EGTA used with a dilute TRIS buffer at pH 7.2-7.5 was used in order to effect a good separation of brush borders from the epithelium of the small intestine. A good separation was not obtained in low concentrations of TRIS buffer or saline alone. Brush borders were not obtained when the calcium-chelate complex of EDTA or EGTA was used, and only a partial fractionation was obtained when the magnesium complex of EDTA was tried. The involvement of calcium was further illustrated by adding calcium salts directly to the fractionation medium; separation was prevented when sufficient calcium had been added to saturate the chelating agent. It was found that there was no precise optimum concentration for EDTA but a separation could not be obtained below 2.4 mM/1. The effect of changing the pH of the buffer was also investigated and it was demonstrated that the onset of the ability to release brush borders coincided approximately with the ionization of the third acid radical of the chelating agent. This is in keeping with the suggested hypothesis that EDTA acts by chelating calcium ions. From these and electron-microscope studies it is suggested that the binding of calcium ions is an important factor in the maintenance of the stability of the epithelial cell membrane.

Sign in / Sign up

Export Citation Format

Share Document