The influence of internal and external diffusional limitations on the observed kinetics of immobilized whole bacterial cells with cell-associated ?-glucosidase activity

1983 ◽  
Vol 5 (2) ◽  
pp. 79-84 ◽  
Author(s):  
Margaret A. Wheatley ◽  
Colin R. Phillips
Keyword(s):  
Bacterial Cells ◽  
Glucosidase Activity ◽  
Kinetics Of

BIOSYNTHESIS OF LIPIDS IN PLANTS: I. INCORPORATION OF ORTHOPHOSPHATE-32P AND GLYCEROPHOSPHATE-32P INTO PHOSPHATIDES OF CHLORELLA VULGARIS DURING PHOTOSYNTHESIS

1965 ◽  
Vol 43 (9) ◽  
pp. 1445-1453 ◽  
Author(s):  
P. S. Sastry ◽  
M. Kates
Keyword(s):  
Chlorella Vulgaris ◽  
Phosphatidyl Ethanolamine ◽  
Phosphatidyl Inositol ◽  
Biosynthetic Pathways ◽  
Bacterial Cells ◽  
Phosphatidyl Glycerol ◽  
Kinetics Of

The kinetics of incorporation of 32P from orthophosphate-32P or DL-α-glycerophosphate-32P into the phosphatides of Chlorella vulgaris during photosynthesis was studied. Rapid labelling of phosphatidyl glycerol was observed with both precursors, followed by lower rates of incorporation into lecithin, phosphatidyl ethanolamine, and phosphatidyl inositol. The results are discussed in the light of biosynthetic pathways known for animal and bacterial cells.

scholarly journals Under-Oil Autonomously Regulated Oxygen Microenvironments: A Goldilocks Principle-Based Approach For Microscale Cell Culture

2020 ◽  
Author(s):  
Chao Li ◽  
Mouhita Humayun ◽  
Glenn M Walker ◽  
Keon Young Park ◽  
Bryce Connors ◽  
...  
Keyword(s):  
Cell Culture ◽  
Cell Types ◽  
Bacterial Cells ◽  
Intestinal Epithelial ◽  
Oxygen Levels ◽  
Disease States ◽  
Cell Culture Systems ◽  
Kinetics Of

Oxygen levels in vivo are autonomously regulated by a supply-demand balance, which can be altered in disease states. However, the oxygen levels of in vitro cell culture systems, particularly microscale cell culture, are typically dominated by either supply or demand. Further, the oxygen microenvironment in these systems are rarely monitored or reported. Here, we present a method to establish and dynamically monitor autonomously regulated oxygen microenvironments (AROM) using an oil overlay in an open microscale cell culture system. Using this method, the oxygen microenvironment is dynamically regulated via a supply-demand balance of the system. We simulate the kinetics of oxygen diffusion in multiliquid-phase microsystems on COMSOL Multiphysics and experimentally validate the method using a variety of cell types including mammalian, fungal and bacterial cells. Finally, we demonstrate the utility of this method to establish a co-culture between primary intestinal epithelial cells and a highly prevalent human gut species Bacteroides uniformis.

scholarly journals A Colorimetric Assay to Quantify Dehydrogenase Activity in Crude Cell Lysates

2002 ◽  
Vol 7 (2) ◽  
pp. 135-140 ◽  
Author(s):  
Kimberly M. Mayer ◽  
Frances H. Arnold
Keyword(s):  
Polymerase Chain Reaction ◽  
Dehydrogenase Activity ◽  
Colorimetric Assay ◽  
Bacterial Cells ◽  
Phenazine Methosulfate ◽  
Chain Reaction ◽  
Phosphogluconate Dehydrogenase ◽  
Polymerase Chain ◽  
Kinetics Of ◽  
Purple Formazan

Nitroblue tetrazolium (NBT) in the presence of phenazine methosulfate (PMS) reacts with the NADPH produced by dehydrogenases to produce an insoluble blue-purple formazan. Endpoint assays taking advantage of this reaction have been successfully used to detect the activity of several dehydrogenases. Here we present a version of this assay suitable for determining the kinetics of 6-phosphogluconate dehydrogenase catalysis in crude lysates of bacterial cells prepared in 96-well plates. Using the assay to screen a small library of variant 6-phosphogluconate dehydrogenases generated by error-prone polymerase chain reaction, we were able to identify three variants with improved activity and thermostability over the parent enzyme. These enzymes were partially purified and shown to be expressed at higher levels than the parent (leading to the increase in activity), and all three variants were indeed more thermostable than the parent (temperature midpoints 4-7°C higher) after purification. Thus the NBT-PMS assay appears suitable for screening libraries of variant dehydrogenases.

scholarly journals The BclB Glycoprotein of Bacillus anthracis Is Involved in Exosporium Integrity

2007 ◽  
Vol 189 (18) ◽  
pp. 6704-6713 ◽  
Author(s):  
Brian M. Thompson ◽  
Lashanda N. Waller ◽  
Karen F. Fox ◽  
Alvin Fox ◽  
George C. Stewart
Keyword(s):  
Bacillus Anthracis ◽  
Mutant Strain ◽  
Basal Layer ◽  
Structural Defects ◽  
Bacterial Cells ◽  
Wild Type ◽  
Fatal Disease ◽  
Specific Location ◽  
Immunofluorescence Studies ◽  
Kinetics Of

ABSTRACT Anthrax is a highly fatal disease caused by the gram-positive, endospore-forming, rod-shaped bacterium Bacillus anthracis. Spores, rather than vegetative bacterial cells, are the source of anthrax infections. Spores of B. anthracis are enclosed by a prominent loose-fitting structure called the exosporium. The exosporium is composed of a basal layer and an external hair-like nap. Filaments of the hair-like nap are made up largely of a single collagen-like glycoprotein called BclA. A second glycoprotein, BclB, has been identified in the exosporium layer. The specific location of this glycoprotein within the exosporium layer and its role in the biology of the spore are unknown. We created a mutant strain of B. anthracis ΔSterne that carries a deletion of the bclB gene. The mutant was found to possess structural defects in the exosporium layer of the spore (visualized by electron microscopy, immunofluorescence, and flow cytometry) resulting in an exosporium that is more fragile than that of a wild-type spore and is easily lost. Immunofluorescence studies also indicated that the mutant strain produced spores with increased levels of the BclA glycoprotein accessible to the antibodies on the surface. The resistance properties of the mutant spores were unchanged from those of the wild-type spores. A bclB mutation did not affect spore germination or kinetics of spore survival within macrophages. BclB plays a key role in the formation and maintenance of the exosporium structure in B. anthracis.

Kinetics of the reduction of tetrathionate by intact bacterial cells

1969 ◽  
Vol 14 (5) ◽  
pp. 460-469 ◽  
Author(s):  
F. Kaprálek ◽  
F. Pichinoty ◽  
J. Riegrová
Keyword(s):  
Bacterial Cells ◽  
Kinetics Of

scholarly journals Phytochemical Analysis, α-glucosidase Inhibition Activity in-vitro and Enzyme Kinetics of Ethyl Acetate and Hexane Extracts of Graptophylum pictum (L.) Griff

2014 ◽  
Vol 1 (2) ◽  
pp. 58-65
Author(s):  
Waras Nurcholis ◽  
I Made Artika ◽  
Djarot Sasongko Hami Seno ◽  
Dimas Andrianto ◽  
Apipah Aprianti ◽  
...  
Keyword(s):  
Ethyl Acetate ◽  
Enzyme Kinetics ◽  
Ethyl Acetate Extract ◽  
Digestive Enzyme ◽  
Hexane Extract ◽  
Phytochemical Analysis ◽  
Herbaceous Plant ◽  
Glucosidase Activity ◽  
Hexane Extracts ◽  
Kinetics Of

The species Graptophylum pictum (L.) Griff, also known as “daun ungu” in Indonesia, is a traditional herbaceous plant believed to have antidiabetic potential. The number of people in the world with diabetes has increased dramatically over the recent years. The treatment of type II diabetes is complicated by several factors inherent to the disease. Elevated postprandial hyperglycemia is one of the risk factors and the intestinal digestive enzyme α-glucosidase plays a vital role in carbohydrate metabolism. One of the antidiabetic therapeutic approaches which reduces the postprandial glucose level in blood is by the inhibition of α-glucosidase. In this study, phytochemical analysis, α- glucosidase inhibitory activity and enzyme kinetics of ethyl acetate- and hexane extracts of G. pictum were evaluated with the aim to analyze its antidiabetic potential. Phytochemical analysis revealed the presence of tannins, steroids, and alkaloids. Steroids were present in ethyl acetate extract but absent in hexane extract, while alkaloids were present in hexane extract but absent in ethyl acetate extract. The ethyl acetate and hexane extracts had 30.68 and 49.82 % inhibitory effect on α-glucosidase activity respectively. The kinetics of glucosidase enzyme of ethyl acetate and hexane extracts were determined by Lineweaver Burk plots. These exhibited uncompetitive and noncompetitive inhibition to alpha-glucosidase activity respectively. From the enzyme assay, we infer that ethyl acetate and hexane extracts of G. pictum contain potential α-glucosidase inhibitors that have the potential to be exploited for use in the treatment of diabetes

scholarly journals Cloning and Characterization of Aedes aegypti Trypsin Modulating Oostatic Factor (TMOF) Gut Receptor

Biomolecules ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 934
Author(s):  
Dov Borovsky ◽  
Kato Deckers ◽  
Anne Catherine Vanhove ◽  
Maud Verstraete ◽  
Pierre Rougé ◽  
...  
Keyword(s):  
Binding Sites ◽  
Protein Sequence ◽  
Bacterial Cells ◽  
E Coli ◽  
Trypsin Modulating Oostatic Factor ◽  
High Affinity ◽  
Sds Page ◽  
Atpase Inhibitors ◽  
Kinetics Of

Trypsin Modulating Oostatic Factor (TMOF) receptor was solubilized from the guts of female Ae. Aegypti and cross linked to His6-TMOF and purified by Ni affinity chromatography. SDS PAGE identified two protein bands (45 and 61 kDa). The bands were cut digested and analyzed using MS/MS identifying a protein sequence (1306 amino acids) in the genome of Ae. aegypti. The mRNA of the receptor was extracted, the cDNA sequenced and cloned into pTAC-MAT-2. E. coli SbmA− was transformed with the recombinant plasmid and the receptor was expressed in the inner membrane of the bacterial cell. The binding kinetics of TMOF-FITC was then followed showing that the cloned receptor exhibits high affinity to TMOF (KD = 113.7 ± 18 nM ± SEM and Bmax = 28.7 ± 1.8 pmol ± SEM). Incubation of TMOF-FITC with E. coli cells that express the receptor show that the receptor binds TMOF and imports it into the bacterial cells, indicating that in mosquitoes the receptor imports TMOF into the gut epithelial cells. A 3D modeling of the receptor indicates that the receptor has ATP binding sites and TMOF transport into recombinant E. coli cells is inhibited with ATPase inhibitors Na Arsenate and Na Azide.

Adsorption kinetics of Escherichia coli and Staphylococcus aureus on single-walled carbon nanotube aggregates

2008 ◽  
Vol 58 (1) ◽  
pp. 179-184 ◽  
Author(s):  
Venkata K. K. Upadhyayula ◽  
Shuguang Deng ◽  
Martha C. Mitchell ◽  
Geoffrey B. Smith ◽  
Vinod K. Nair ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Staphylococcus Aureus ◽  
Carbon Nanotube ◽  
Batch Adsorption ◽  
Bacterial Cells ◽  
Single Walled Carbon Nanotube ◽  
E Coli ◽  
Single Walled Carbon ◽  
Kinetics Of ◽  
And Staphylococcus Aureus

Batch adsorption studies to determine adsorption kinetics of Escherichia coli (E.coli) K12 and Staphylococcus aureus (S.aureus) SH 1000 bacterial cells on single-walled carbon nanotube aggregates were performed at two different initial concentrations. The diffusivity of E. coli cells in single-walled carbon nanotube aggregates obtained was 6.54 × 10−9 and 8.98 × 10–9 cm2/s, whereas that of S. aureus was between 1.00 × 10–7 and 1.66 × 10–7 cm2/s respectively. In addition to batch adsorption studies, electron microscopy studies were also conducted. The results suggest that diffusion kinetics of bacterial cells is concentration dependent as well as bacteria dependent. Diffusivity of S. aureus is two orders of magnitude greater than E. coli cells. This proves to be beneficial from an adsorption perspective where it is desired to filter microorganisms (water pretreatment and wastewater post treatment) and from nanotube biosensor perspective where it is desired to simultaneously capture and detect biothreat agents in a shorter span of time.

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