On the potential significance of the enzymatic activity of mite allergens to immunogenicity. Clues to structure and function revealed by molecular characterization

1997 ◽  
Vol 27 (1) ◽  
pp. 10-21 ◽  
Author(s):  
C. ROBINSON ◽  
N. A. KALSHEKER ◽  
N. SRINIVASAN ◽  
C. M. KING ◽  
D. R. GARROD ◽  
...  
Keyword(s):  
Enzymatic Activity ◽  
Molecular Characterization ◽  
Structure And Function ◽  
Potential Significance ◽  
And Function

scholarly journals The encapsulin from Thermatoga maritima is a flavoprotein with a symmetry matched ferritin-like cargo protein

2021 ◽  
Author(s):  
Benjamin J LaFrance ◽  
Caleb Cassidy-Amstutz ◽  
Robert J Nichols ◽  
Luke M Oltrogge ◽  
Eva Nogales ◽  
...  
Keyword(s):  
Enzymatic Activity ◽  
Biochemical Analysis ◽  
Active Role ◽  
Structure And Function ◽  
Redox Active ◽  
Cargo Protein ◽  
Cargo Proteins ◽  
And Function ◽  
Flavin Binding ◽  
Unique Chemical

Bacterial nanocompartments, also known as encapsulins, are an emerging class of protein-based "organelles" found in bacteria and archaea. Encapsulins are virus-like icosahedral particles comprising a ~25-50 nm shell surrounding a specific cargo enzyme. Compartmentalization is thought to create a unique chemical environment to facilitate catalysis and isolate toxic intermediates. Many questions regarding nanocompartment structure-function remain unanswered, including how shell symmetry dictates cargo loading and to what extent the shell facilitates enzymatic activity. Here, we explore these questions using the model T. maritima nanocompartment known to encapsulate a redox-active ferritin-like protein. Biochemical analysis revealed the encapsulin shell to possess a flavin binding site located at the interface between capsomere subunits, suggesting the shell may play a direct and active role in the function of the encapsulated cargo. Furthermore, we used cryoEM to show that cargo proteins use a form of symmetry-matching to facilitate encapsulation and define stoichiometry. In the case of the T. maritima encapsulin, the decameric cargo protein with 5-fold symmetry preferentially binds to the pentameric-axis of the icosahedral shell. Taken together, these observations suggest the shell is not simply a passive barrier-it also plays a significant role in the structure and function of the cargo enzyme.

scholarly journals N-linked Oligosaccharides Affect the Enzymatic Activity of CD39: Diverse Interactions between Seven N-linked Glycosylation Sites

2005 ◽  
Vol 16 (4) ◽  
pp. 1661-1672 ◽  
Author(s):  
James J. Wu ◽  
Lisa E. Choi ◽  
Guido Guidotti
Keyword(s):  
Enzymatic Activity ◽  
Surface Expression ◽  
Structure And Function ◽  
Surface Appearance ◽  
C Terminus ◽  
Glycosylation Sites ◽  
N Terminus ◽  
Membrane Bound ◽  
And Function ◽  
Diverse Interactions

Rat CD39, a membrane-bound ectonucleoside triphosphate diphosphohydrolase that hydrolyzes extracellular nucleoside tri- and diphosphates, has seven potential N-glycosylation sites at asparagine residues 73, 226, 291, 333, 375, 429, and 458. To determine their roles in the structure and function of CD39, we mutated these sites individually or in combination by replacing asparagine with serine or glutamine and analyzed the surface expression and the enzymatic activity of the mutants. The results indicate that rat CD39 can be glycosylated at all seven sites when expressed in COS7 cells. Glycosylation sites 73 at the N terminus, 333 in the middle, and 429 and 458 at the C terminus were principally required for cell surface appearance of enzymatically active CD39. Whereas deletion of these sites individually had modest effects on surface ATPase activity, some double deletions of these sites had major effects on both surface activity and expression. The importance of these N-glycosylation sites is recognizable in other members of the ectonucleoside triphosphate diphosphohydrolase family.

scholarly journals Exploring the influence of silver and lead on structure and function of xylanase: spectroscopic and calorimetric methods

2020 ◽  
Vol 9 (3) ◽  
pp. 182-190
Author(s):  
Mingyang Jing ◽  
Rui Tang ◽  
Guangye Han ◽  
Shansheng Zhang ◽  
Rutao Liu
Keyword(s):  
Enzymatic Activity ◽  
Molecular Level ◽  
Structure And Function ◽  
Titration Calorimetry ◽  
Soil Enzyme Activities ◽  
Hydrophobic Force ◽  
Negative Effect ◽  
Endogenous Fluorescence ◽  
Underlying Mechanisms ◽  
And Function

Abstract Soil contamination with heavy metal could induce the alteration of soil ecological environments, and soil enzyme activities are sensitive indicators for the soil toxicology. Xylanase is one of predominant soil enzymes related to carbon nitrogen cycle. In this work, we explored the underlying mechanisms for conformational and enzymatic activity alterations of xylanase after silver and lead exposure at molecular level with systematical measurements including multiple spectroscopic methods, isothermal titration calorimetry, and enzymatic activity. Both silver and lead could loosen and unfold the skeleton of xylanase with the quenching of endogenous fluorescence. Silver interacted with xylanase forming larger-size aggregations through Van der Waals forces and hydrogen bonding, while lead interacted with xylanase forming larger-size aggregations through hydrophobic force. Silver and lead induced an obvious loss (67.1 and 56.31%) of the xylanase enzymatic activity, but silver has a greater impact on xylanase than that of lead. The xylanase enzymatic activity significantly decreased due to the conformational alterations. The negative effect of silver exposure on xylanase structure and function was more prominent than that of lead.

Structure and function of neural networks in the retina

1988 ◽  
Vol 46 ◽  
pp. 26-27
Author(s):  
Peter Sterling
Keyword(s):  
Ganglion Cells ◽  
Three Dimensional ◽  
Structure And Function ◽  
Synaptic Connections ◽  
Visual Axis ◽  
One Dimensional ◽  
Cat Retina ◽  
Ultrathin Sections ◽  
And Function ◽  
Insight Into

The synaptic connections in cat retina that link photoreceptors to ganglion cells have been analyzed quantitatively. Our approach has been to prepare serial, ultrathin sections and photograph en montage at low magnification (˜2000X) in the electron microscope. Six series, 100-300 sections long, have been prepared over the last decade. They derive from different cats but always from the same region of retina, about one degree from the center of the visual axis. The material has been analyzed by reconstructing adjacent neurons in each array and then identifying systematically the synaptic connections between arrays. Most reconstructions were done manually by tracing the outlines of processes in successive sections onto acetate sheets aligned on a cartoonist's jig. The tracings were then digitized, stacked by computer, and printed with the hidden lines removed. The results have provided rather than the usual one-dimensional account of pathways, a three-dimensional account of circuits. From this has emerged insight into the functional architecture.

Osseointegration interface of calcified bone and endosseous implants

1992 ◽  
Vol 50 (2) ◽  
pp. 1096-1097
Author(s):  
K.E. Krizan ◽  
J.E. Laffoon ◽  
M.J. Buckley
Keyword(s):  
Structure And Function ◽  
Titanium Implants ◽  
En Bloc ◽  
Endosseous Implants ◽  
Ultrastructural Studies ◽  
The Past ◽  
Cacodylate Buffer ◽  
One Year ◽  
And Function

With increase use of tissue-integrated prostheses in recent years it is a goal to understand what is happening at the interface between haversion bone and bulk metal. This study uses electron microscopy (EM) techniques to establish parameters for osseointegration (structure and function between bone and nonload-carrying implants) in an animal model. In the past the interface has been evaluated extensively with light microscopy methods. Today researchers are using the EM for ultrastructural studies of the bone tissue and implant responses to an in vivo environment. Under general anesthesia nine adult mongrel dogs received three Brånemark (Nobelpharma) 3.75 × 7 mm titanium implants surgical placed in their left zygomatic arch. After a one year healing period the animals were injected with a routine bone marker (oxytetracycline), euthanized and perfused via aortic cannulation with 3% glutaraldehyde in 0.1M cacodylate buffer pH 7.2. Implants were retrieved en bloc, harvest radiographs made (Fig. 1), and routinely embedded in plastic. Tissue and implants were cut into 300 micron thick wafers, longitudinally to the implant with an Isomet saw and diamond wafering blade [Beuhler] until the center of the implant was reached.

Use of human autoantibodies and immunoelectron microscopy to study structure and function of the nucleolus and nuclear bodies

1992 ◽  
Vol 50 (1) ◽  
pp. 506-507
Author(s):  
Robert L. Ochs
Keyword(s):  
Electron Microscopy ◽  
Structure And Function ◽  
Nuclear Bodies ◽  
Nuclear Interior ◽  
Coiled Bodies ◽  
Interchromatin Granules ◽  
And Function ◽  
Conventional Electron Microscopy ◽  
Perichromatin Granules ◽  
Perichromatin Fibrils

By conventional electron microscopy, the formed elements of the nuclear interior include the nucleolus, chromatin, interchromatin granules, perichromatin granules, perichromatin fibrils, and various types of nuclear bodies (Figs. 1a-c). Of these structures, all have been reasonably well characterized structurally and functionally except for nuclear bodies. The most common types of nuclear bodies are simple nuclear bodies and coiled bodies (Figs. 1a,c). Since nuclear bodies are small in size (0.2-1.0 μm in diameter) and infrequent in number, they are often overlooked or simply not observed in any random thin section. The rat liver hepatocyte in Fig. 1b is a case in point. Historically, nuclear bodies are more prominent in hyperactive cells, they often occur in proximity to nucleoli (Fig. 1c), and sometimes they are observed to “bud off” from the nucleolar surface.

Depletion and Reconstitution of Active E. Coli Ribosomes

1975 ◽  
Vol 33 ◽  
pp. 640-641
Author(s):  
M. Boublik ◽  
W. Hellmann ◽  
F. Jenkins
Keyword(s):  
Protein Biosynthesis ◽  
Large Subunit ◽  
High Resolution Electron Microscopy ◽  
Small Subunit ◽  
Structure And Function ◽  
Biologically Active ◽  
Biological Macromolecules ◽  
E Coli ◽  
Resolution Electron ◽  
And Function

Correlations between structure and function of biological macromolecules have been studied intensively for many years, mostly by indirect methods. High resolution electron microscopy is a unique tool which can provide such information directly by comparing the conformation of biopolymers in their biologically active and inactive state. We have correlated the structure and function of ribosomes, ribonucleoprotein particles which are the site of protein biosynthesis. 70S E. coli ribosomes, used in this experiment, are composed of two subunits - large (50S) and small (30S). The large subunit consists of 34 proteins and two different ribonucleic acid molecules. The small subunit contains 21 proteins and one RNA molecule. All proteins (with the exception of L7 and L12) are present in one copy per ribosome.This study deals with the changes in the fine structure of E. coli ribosomes depleted of proteins L7 and L12. These proteins are unique in many aspects.

The Laryngeal Epithelium in Reflux

2011 ◽  
Vol 21 (3) ◽  
pp. 112-117 ◽  
Author(s):  
Elizabeth Erickson-Levendoski ◽  
Mahalakshmi Sivasankar
Keyword(s):  
Laryngopharyngeal Reflux ◽  
Critical Role ◽  
Structure And Function ◽  
Laryngeal Disease ◽  
Health And Disease ◽  
And Function ◽  
The Impact

The epithelium plays a critical role in the maintenance of laryngeal health. This is evident in that laryngeal disease may result when the integrity of the epithelium is compromised by insults such as laryngopharyngeal reflux. In this article, we will review the structure and function of the laryngeal epithelium and summarize the impact of laryngopharyngeal reflux on the epithelium. Research investigating the ramifications of reflux on the epithelium has improved our understanding of laryngeal disease associated with laryngopharyngeal reflux. It further highlights the need for continued research on the laryngeal epithelium in health and disease.

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