β-Lactamase activity of Escherichia intermedia

1968 ◽  
Vol 14 (4) ◽  
pp. 349-354 ◽  
Author(s):  
F. M. Huber ◽  
P. G. Caltrider ◽  
Susanne Noble
Keyword(s):  
Marked Effect ◽  
Specific Activity ◽  
Culture Conditions ◽  
Physiological Age ◽  
Cephalosporin C ◽  
Intact Cells ◽  
A Cell ◽  
Rate Of Hydrolysis ◽  
Gram Negative Organisms ◽  
Derivatives Of

Escherichia intermedia was found to produce a β-lactamase that hydrolyzed several penicillin and cephalosporin C derivatives. Culture conditions affecting production of the enzyme were studied. The enzyme was non-inducible and cell-bound. Growth temperature, medium, and physiological age had a marked effect on production of the enzyme. Properties of the enzyme were studied with intact cells and with a cell-free preparation. Although the β-lactamase of E. intermedia was different in some respects to that produced by gram-positive organisms, it was found to have properties similar to the β-lactamases of gram-negative organisms. 6-Aminopenicillanic acid was cleaved by the enzyme, but 7-aminocephalosporanic acid was resistant to cleavage. The rate of hydrolysis by intact cells and the purified preparation was influenced by the type of N-acyl sidechain of 7-aminocephalosporanic acid and 6-aminopenicillanic acid. The desacetoxy derivatives of cephalosporin C and cephalothin were hydrolyzed less rapidly than the parent compounds. The specific activity of the intact cells on cephalonium and methicillin was substantially less than that of the purified preparation.

scholarly journals Properties of β-lactamases produced by three species of mycobacteria

1968 ◽  
Vol 107 (5) ◽  
pp. 675-682 ◽  
Author(s):  
J. E. Kasik ◽  
Lin Peacham
Keyword(s):  
Mycobacterium Smegmatis ◽  
Extracellular Fluid ◽  
Gram Negative Bacteria ◽  
Cephalosporin C ◽  
Gram Positive ◽  
Intact Cells ◽  
Gram Negative ◽  
Substrate Specificities ◽  
High Concentrations ◽  
Derivatives Of

1. Mycobacterium smegmatis (N.C.T.C. 8158), M. fortuitum and M. phlei (MPI) produce a constitutive β-lactamase that has penicillinase and cephalosporinase activity. 2. The β-lactamases of these three species of acid-fast bacteria were mainly cell-bound, only small amounts of activity being liberated into the extracellular fluid. The total β-lactamase activity of these mycobacteria was much lower than that of certain Gram-positive organisms, but comparable with that reported for species of Gram-negative bacteria. 3. The β-lactamases of intact cells of the mycobacteria were not freely accessible to any of the substrates tested, but the apparent crypticity factor to benzylpenicillin was greater than that to cephaloridine and cephalosporin C. 4. Attempts to induce β-lactamase activity in M. smegmatis and M. phlei failed even with high concentrations of inducer. 5. The β-lactamases obtained from the three species of mycobacteria showed different substrate specificities, including different relative activities as cephalosporinases and penicillinases respectively. 6. Certain derivatives of 6-aminopenicillanic acid and 7-aminocephalosporanic acid were found to be resistant to hydrolysis by β-lactamases of M. smegmatis and M. fortuitum. 7. The β-lactamase of M. smegmatis was competitively inhibited by a number of β-lactamase-resistant derivatives of 6-aminopenicillanic acid, but not by similar derivatives of 7-aminocephalosporanic acid.

Enhancement of microsomal phosphatidate phosphohydrolase and diacylglycerol acyltransferase activity by insulin during growth of rat adipocyte precursors in culture

1979 ◽  
Vol 57 (6) ◽  
pp. 573-577 ◽  
Author(s):  
Daniel A. K. Roncari ◽  
Esther Y. W. Mack ◽  
Dominic K. Yip
Keyword(s):  
Enzyme Activity ◽  
Specific Activity ◽  
Diacylglycerol Acyltransferase ◽  
Culture Conditions ◽  
Acyltransferase Activity ◽  
Intact Cells ◽  
Triacylglycerol Synthesis ◽  
Phosphatidate Phosphohydrolase ◽  
Morphological Maturation ◽  
Adipocyte Precursor

The availability of a propagating adipocyte precursor culture system has provided the opportunity to study biochemical processes under conditions in which any known interacting influences are controlled. We have studied the activity of various triacylglycerol-biosynthetic enzymes during maturation of rat epididymal adipocyte precursors and any possible effect of insulin on enzyme activity. At certain times in culture, the specific activity of microsomal phosphatidate phosphohydrolase (EC 3.1.3.4) and diacylglycerol acyltransferase (EC 2.3.1.20) is significantly enhanced in cells grown in the presence of added insulin. Under the culture conditions used in this study, the adipocyte precursors acquire several small lipid inclusions and become rounder, but do not assume the signet-ring appearance of mature fat cells during the first 2 weeks of monolayer confluence. Consequently, the effects of the hormone on enzyme activity become evident prior to complete morphological maturation. Phosphatidate phosphohydrolase is believed to be a rate-controlling enzyme in triacylglycerol synthesis in adipose tissue and liver. The fact that the adipocyte precursor microsomal, rather than cytosolic, phosphohydrolase is influenced by insulin suggests that the membrane-bound enzyme is the regulatory phosphohydrolase in intact cells. The enhancement of diacylglycerol acyltransferase activity may be of significance in the reesterification of fatty acids with diacylglycerols, a reaction that by passes the phosphohydrolase step. Thus, in addition to the well-known mechanisms by which insulin promotes triacylglycerol accretion in adipocytes and their precursors, the hormone significantly enhances the specific activity of critical enzymes of triacylglycerol synthesis.

Synthesis and Antimicrobial Activity of Adamantyl Substituted Pyridoxine Derivatives

2019 ◽  
Vol 16 (12) ◽  
pp. 1360-1369 ◽  
Author(s):  
Rail Khaziev ◽  
Nikita Shtyrlin ◽  
Roman Pavelyev ◽  
Raushan Nigmatullin ◽  
Raylya Gabbasova ◽  
...  
Keyword(s):  
Influenza Virus ◽  
Lipid Membranes ◽  
Specific Activity ◽  
Tuberculosis H37rv ◽  
Microbial Pathogens ◽  
Adamantane Derivatives ◽  
Carbon Cage ◽  
H37rv Strain ◽  
Derivatives Of

Background: Adamantane derivatives possess multiple pharmacological activities such as antiviral, anticancer, antimycobacterial, antidiabetic, antiparkinsonian and others. The interest of medicinal chemists in adamantane compounds is due to their unique spatial structure, high lipophilicity, and carbon cage rigidity. As a result, these molecules can easily penetrate biological lipid membranes and often have unique target-specific activity profile. Another pharmacophore studied in this work is pyridoxine (vitamin B6). Pyridoxine plays highly important roles in living cells as a key cofactor of many enzymes. On the other hand, its molecular scaffold is a valuable structural platform which has led to the development of several launched drugs (Pyritinol, Pirisudanol, Cycletanine, Mangafodipir) and a wide number of preclinical and clinical drug candidates. Objective: The objective of this study is a synthesis of pyridoxine-adamantane and pyridoxinecyclooctane dipharmacophore molecules. The underlying idea was to assess the antibacterial and antiviral potential of such dipharmacophores, based on multiple examples of promising antiinfective agents which have in their structures adamantane and pyridoxine moieties. Another specific reason was to explore the ability of pyridoxine pharmacophore to suppress the potential of microbial pathogens to develop resistance to drug molecules. Methods: In this study, a series of pyridoxine-adamantane and pyridoxine-cyclooctane dipharmacophore molecules were synthesized based on reactions of three different cycloalkyl amines with the corresponding electrophilic derivatives of pyridoxine aldehydes, chlorides and acetates. All synthesized compounds have been tested for their in vitro activity against M. tuberculosis H37Rv strain and H3N2 (A/Aichi/2/68) influenza virus. Results: Series of pyridoxine-adamantane and pyridoxine-cyclooctane dipharmacophore molecules were synthesized based on reactions of three different cycloalkylamines with the corresponding electrophilic derivatives of pyridoxine aldehydes, chlorides and acetates. Reaction of cycloalkylamines with pyridoxine derivatives, in which meta-hydroxyl and ortho-hydroxymethyl groups are protected by acetyl groups, represents a useful alternative to reductive amination of aldehydes and nucleophilic substitution of alkyl halides. According to a tentative mechanism, it proceeds via paraand ortho-pyridinone methides which readily react with nucleophiles. None of the synthesized dipharmacophore compounds showed activity against M. tuberculosis H37Rv strain. At the same time, three compounds demonstrated some antiviral activity against H3N2 (A/Aichi/2/68) influenza virus (EC50 52-88 µg/mL) that was comparable to the activity of Amantadine, though lower than the activity of Rimantadine. The results of this work can be useful in the design of physiologically active derivatives of pyridoxine and adamantane. Conclusion: The results of this work can be useful in the design of physiologically active derivatives of pyridoxine and adamantane.

scholarly journals The effect of age on protein synthesis in mouse liver

1969 ◽  
Vol 113 (5) ◽  
pp. 869-878 ◽  
Author(s):  
W. I. P. Mainwaring
Keyword(s):  
Messenger Rna ◽  
Mouse Liver ◽  
Direct Evidence ◽  
Similar System ◽  
Ribonucleoprotein Particles ◽  
Polyuridylic Acid ◽  
A Cell ◽  
Rate Of Hydrolysis ◽  
Old Mice ◽  
Effect Of Age

1. A system of microsomes and 105000g supernatant from livers of old mice is less able to promote the incorporation of [14C]phenylalanine into protein than a similar system from livers of young animals. 2. The decrease in [14C]phenylalanine incorporation is attributable to changes in microsomes from old animals rather than in the cell-sap fraction. 3. Decreased synthetic ability is found in various classes of microsomes from older animals, namely unfractionated, light and heavy microsomes, but not in detergent-washed ribonucleoprotein particles. 4. Deletions of certain detergent-soluble microsomal proteins accompany the decreased synthetic ability of microsomes from older animals. 5. Microsomes from old mice are less responsive to a synthetic messenger RNA, polyuridylic acid, and this is partly due to a higher rate of hydrolysis in the presence of cell sap from animals of extreme age. 6. Other more direct evidence, from the priming of a cell-free protein-synthesizing system from bacteria and the examination of ribonucleoprotein particles on sucrose density gradients, suggests that senescence is accompanied by a decrease in messenger RNA content.

scholarly journals Identification of Hepatitis C Virus NS5A Inhibitors

2009 ◽  
Vol 84 (1) ◽  
pp. 482-491 ◽  
Author(s):  
Julie A. Lemm ◽  
Donald O'Boyle ◽  
Mengping Liu ◽  
Peter T. Nower ◽  
Richard Colonno ◽  
...  
Keyword(s):  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Amino Acid ◽  
Therapeutic Index ◽  
Dna Viruses ◽  
Genotype 1A ◽  
A Cell ◽  
Ns3 Protease ◽  
Derivatives Of ◽  
Rna And Dna

ABSTRACT Using a cell-based replicon screen, we identified a class of compounds with a thiazolidinone core structure as inhibitors of hepatitis C virus (HCV) replication. The concentration of one such compound, BMS-824, that resulted in a 50% inhibition of HCV replicon replication was ∼5 nM, with a therapeutic index of >10,000. The compound showed good specificity for HCV, as it was not active against several other RNA and DNA viruses. Replicon cells resistant to BMS-824 were isolated, and mutations were identified. A combination of amino acid substitutions of leucine to valine at residue 31 (L31V) and glutamine to leucine at residue 54 (Q54L) in NS5A conferred resistance to this chemotype, as did a single substitution of tyrosine to histidine at amino acid 93 (Y93H) in NS5A. To further explore the region(s) of NS5A involved in inhibitor sensitivity, genotype-specific NS5A inhibitors were used to evaluate a series of genotype 1a/1b hybrid replicons. Our results showed that, consistent with resistance mapping, the inhibitor sensitivity domain also mapped to the N terminus of NS5A, but it could be distinguished from the key resistance sites. In addition, we demonstrated that NS5A inhibitors, as well as an active-site inhibitor that specifically binds NS3 protease, could block the hyperphosphorylation of NS5A, which is believed to play an essential role in the viral life cycle. Clinical proof of concept has recently been achieved with derivatives of these NS5A inhibitors, indicating that small molecules targeting a nontraditional viral protein like NS5A, without any known enzymatic activity, can also have profound antiviral effects on HCV-infected subjects.

scholarly journals Studies on the production of glucose isomerase by Bacillus licheniformis

2015 ◽  
Vol 17 (3) ◽  
pp. 84-88 ◽  
Author(s):  
Ogbonnaya Nwokoro
Keyword(s):  
Enzyme Activity ◽  
Bacillus Licheniformis ◽  
Organic Nitrogen ◽  
Specific Activity ◽  
Inorganic Nitrogen ◽  
Glucose Isomerase ◽  
Culture Conditions ◽  
Enzyme Productivity ◽  
Carbon Substrates ◽  
Optimum Ph

Abstract This work reports the effects of some culture conditions on the production of glucose isomerase by Bacillus licheniformis. The bacterium was selected based on the release of 3.62 mg/mL fructose from the fermentation of glucose. Enzyme was produced using a variety of carbon substrates but the highest enzyme activity was detected in a medium containing 0.5% xylose and 1% glycerol (specific activity = 6.88 U/mg protein). Media containing only xylose or glucose gave lower enzyme productivies (specific activities= 4.60 and 2.35 U/mg protein respectively). The effects of nitrogen substrates on glucose isomerase production showed that yeast extract supported maximum enzyme activity (specific activity = 5.24 U/mg protein). Lowest enzyme activity was observed with sodium trioxonitrate (specific activity = 2.44 U/mg protein). In general, organic nitrogen substrates supported higher enzyme productivity than inorganic nitrogen substrates. Best enzyme activity was observed in the presence of Mg2+ (specific activity = 6.85 U/mg protein) while Hg2+ was inhibitory (specific activity = 1.02 U/mg protein). The optimum pH for best enzyme activity was 6.0 while optimum temperature for enzyme production was 50ºC.

Common precursors for neural and mesectodermal derivatives in the cephalic neural crest

Development ◽  
1991 ◽  
Vol 112 (1) ◽  
pp. 301-305 ◽  
Author(s):  
A. Baroffio ◽  
E. Dupin ◽  
N.M. Le Douarin
Keyword(s):  
Neural Crest ◽  
Cell Types ◽  
Culture Conditions ◽  
Pigment Cells ◽  
Stem Cell Population ◽  
Multipotent Cells ◽  
Clonal Cultures ◽  
Vertebrate Embryos ◽  
Derivatives Of

The cephalic neural crest (NC) of vertebrate embryos yields a variety of cell types belonging to the neuronal, glial, melanocytic and mesectodermal lineages. Using clonal cultures of quail migrating cephalic NC cells, we demonstrated that neurons and glial cells of the peripheral nervous system can originate from the same progenitors as cartilage, one of the mesectodermal derivatives of the NC. Moreover, we obtained evidence that the migrating cephalic NC contains a few highly multipotent precursors that are common to neurons, glia, cartilage and pigment cells and which we interprete as representative of a stem cell population. In contrast, other NC cells, although provided with identical culture conditions, give rise to clones composed of only one or some of these cell types. These cells thus appear restricted in their developmental potentialities compared to multipotent cells. It is therefore proposed that, in vivo, the active proliferation of pluripotent NC cells during the migration process generates distinct subpopulations of cells that become progressively committed to different developmental fates.

Trypanosoma brucei: Ecto-Phosphatase Activity Present on the Surface of Intact Procyclic Forms

1997 ◽  
Vol 52 (5-6) ◽  
pp. 351-358 ◽  
Author(s):  
Eloise C. Fernandes ◽  
José R. Meyer-Fernandes ◽  
Mário A. C. Silva-Neto ◽  
Anibal E. Vercesi
Keyword(s):  
Acid Phosphatase ◽  
Cell Surface ◽  
Cell Viability ◽  
Phosphatase Activity ◽  
Trypanosoma Brucei ◽  
Intact Cells ◽  
Vanadate Inhibition ◽  
Rate Of Hydrolysis ◽  
Ph Range

Abstract The results presented in this paper indicate that procyclic forms of Trypanosoma brucei possess a phosphatase activity detected in the external cell surface able to hydrolyze about 0.7 nmol ∙ mg−1. min−1 p-nitrophenylphosphate. A faster rate of hydrolysis was observed when membrane-enriched fractions were used. This activity is weakly sensitive to 1 mᴍ NaF, 10 mᴍ tartrate and 10 mᴍ levamizole but strongly inhibited by 0.1 mᴍ vanadate. Inhibition by both NaF and vanadate have a competitive character. This phosphatase activity decreases by increasing the pH from 6.8 to 8.4, a pH range in which cell viability was maintained during at least 1 hour. In the membrane-enriched fractions this phosphatase activity showed to be an acid phosphatase. In addition, intact cells could catalyze the dephosphorylation of [32P]phosphocasein phosphorylated at serine and threonine residues.

ENZYME INHIBITION BY DERIVATIVES OF PHENOTHIAZINE VI. INHIBITION OF GLYOXALASE ACTIVITY OF HUMAN AND RABBIT ERYTHROCYTES

1953 ◽  
Vol 31 (3) ◽  
pp. 195-201
Author(s):  
H. B. Collier ◽  
Sheila C. McRae
Keyword(s):  
Methylene Blue ◽  
Enzyme Inhibition ◽  
Strong Inhibitor ◽  
Intact Cells ◽  
Relationship Of ◽  
Derivatives Of

Phenothiazone has been found to be a strong inhibitor of glyoxalase activity of human and rabbit erythrocytes. Concentrations for 50% inhibition were 10−6 M for intact cells and 10−4 M for haemolysates with added glutathione. Glyoxalase activity was also markedly inhibited by phenothiazine, methylene blue, and p-chloromercuribenzoate; slightly inhibited by alloxan and phenylhydrazine; and not affected by dialuric acid. Enzyme inhibition did not parallel methaemoglobin formation. The possible relationship of these findings to the haemolytic action of phenothiazine is discussed.

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