scholarly journals Structure and Function of Nucleoside Hydrolases from Physcomitrella patens and Maize Catalyzing the Hydrolysis of Purine, Pyrimidine, and Cytokinin Ribosides

2013 ◽  
Vol 163 (4) ◽  
pp. 1568-1583 ◽  
Author(s):  
M. Kopecna ◽  
H. Blaschke ◽  
D. Kopecny ◽  
A. Vigouroux ◽  
R. Koncitikova ◽  
...  
Keyword(s):  
Physcomitrella Patens ◽  
Structure And Function ◽  
Nucleoside Hydrolases ◽  
And Function ◽  
Hydrolysis Of ◽  
Purine Pyrimidine

TBC Proteins: Miraculous Regulators of Rabs GTPase Molecular Switches

2021 ◽  
Author(s):  
Jun Yan ◽  
Yingcheng Zheng ◽  
Song Han ◽  
Jun Yin ◽  
Yinping Li ◽  
...  
Keyword(s):  
Amino Acids ◽  
Intracellular Transport ◽  
Molecular Switches ◽  
Small Gtpases ◽  
Structure And Function ◽  
Rab Gtpase ◽  
Cellular Functions ◽  
Eukaryotic Proteins ◽  
And Function ◽  
Hydrolysis Of

TBC proteins are classified as a group because they contain a common conserved structure TBC domain. TBC domain consists of approximately 200 amino acids and presents in many eukaryotic proteins. It is reported that TBC proteins have been shown to function as a GAP for Rab GTPase. TBC proteins catalyze the hydrolysis of GTP and promote the conversion of Rab-GTP to Rab-GDP, thus participating in the specific intracellular transport. Many TBC proteins play important roles in cellular functions in mammals, and their deletions or mutations are closely related to many diseases. It is important to systematically sort out these findings and functions of the TBC family and illuminate the significance of TBC proteins in different physiological conditions. Here we reviewed the structure and function of TBC proteins, especially the function related to to Rab small GTPases.

scholarly journals The effects of tyrosine nitration on the structure and function of hen egg-white lysozyme

1996 ◽  
Vol 315 (2) ◽  
pp. 473-479 ◽  
Author(s):  
Paul G. RICHARDS ◽  
David J. WALTON ◽  
John HEPTINSTALL
Keyword(s):  
Cell Wall ◽  
Egg White ◽  
Structure And Function ◽  
Tyrosine Nitration ◽  
Hen Egg White Lysozyme ◽  
Egg White Lysozyme ◽  
Hen Egg White ◽  
And Function ◽  
Hydrolysis Of ◽  
Hen Egg

We have investigated the effects of tyrosine nitration (to form the weak acid, 3-nitrotyrosine) at positions 23 or 20 plus 23, on the structure and function of hen egg-white lysozyme. Enzyme activity against Micrococcus luteus cell-wall fragments or soluble substrates exhibits two phenomena. (a) A decrease in Km and kcat for the hydrolysis of soluble oligo- and poly-saccharides, resulting in only minor changes in the catalytic efficiency (kcat/Km) upon nitration. (b) The hydrolysis of M. luteus cell-wall fragments appeared to be dominated by electrostatic interactions with the protein, giving a decrease in enzyme activity as the 3-nitrotyrosyl group became ionized. Removal of the cell-wall anionic polymer, teichuronic acid, from M. luteus abolished this effect. The 3-nitrotyrosine group was also found to act as a fluorescence quencher of exposed tryptophan residues in lysozyme.

The structure and function of oestrogens. V. Synthesis of (9,12,12-2H3)- and (11ζ 12,12-2H3)-oestradiol

1983 ◽  
Vol 36 (2) ◽  
pp. 403 ◽  
Author(s):  
DJ Collins
Keyword(s):  
Acid Hydrolysis ◽  
Sodium Borohydride ◽  
Structure And Function ◽  
Borohydride Reduction ◽  
Hydride Reduction ◽  
Biological Studies ◽  
Sodium Borohydride Reduction ◽  
And Function ◽  
Hydrolysis Of

17,17-Ethylenedioxy-3-methoxy(9,12,12-2H3)-9β-oestra-l,3,5(10)-trien-11-one (3) was reduced to the mixture of 11-epimeric alcohols (4) which upon elimination of DHO gave the (12,12-2H2)-9(11)- dehydrooestrone derivative (5b). Treatment of (5b) with (2H6)diborane followed by oxidation afforded the (9,12,12-2H3)alcohol (8a); hydride reduction of the corresponding tosylate then gave 17,17-ethylenedioxy-3-methoxy(9,12,12-2H3)oestra-l,3,5(l0)-triene (7). Acid hydrolysis of (7), followed by demethylation, and reduction with sodium borohydride yielded (9,12,12-2H3)oestradiol (10). Sodium borohydride reduction of (11&12,12-2H3)oestrone (6),prepared in several steps from the 9β,12,12-trideutero ketone (3), gave (11 ξ,12,12-2H3)oestradiol (9). [The two trideuterated oestradiols (9) and (10) were required for biological studies.]

scholarly journals Cryo-EM studies of the structure and dynamics of vacuolar-type ATPases

2016 ◽  
Vol 2 (7) ◽  
pp. e1600725 ◽  
Author(s):  
Mohammad T. Mazhab-Jafari ◽  
John L. Rubinstein
Keyword(s):  
Nmr Spectroscopy ◽  
Structure And Function ◽  
Conformational Heterogeneity ◽  
X Ray ◽  
X Ray Crystallography ◽  
Adenosine Triphosphatases ◽  
Different Types ◽  
Ion Gradient ◽  
And Function ◽  
Hydrolysis Of

Electron cryomicroscopy (cryo-EM) has significantly advanced our understanding of molecular structure in biology. Recent innovations in both hardware and software have made cryo-EM a viable alternative for targets that are not amenable to x-ray crystallography or nuclear magnetic resonance (NMR) spectroscopy. Cryo-EM has even become the method of choice in some situations where x-ray crystallography and NMR spectroscopy are possible but where cryo-EM can determine structures at higher resolution or with less time or effort. Rotary adenosine triphosphatases (ATPases) are crucial to the maintenance of cellular homeostasis. These enzymes couple the synthesis or hydrolysis of adenosine triphosphate to the use or production of a transmembrane electrochemical ion gradient, respectively. However, the membrane-embedded nature and conformational heterogeneity of intact rotary ATPases have prevented their high-resolution structural analysis to date. Recent application of cryo-EM methods to the different types of rotary ATPase has led to sudden advances in understanding the structure and function of these enzymes, revealing significant conformational heterogeneity and characteristic transmembrane α helices that are highly tilted with respect to the membrane. In this Review, we will discuss what has been learned recently about rotary ATPase structure and function, with a particular focus on the vacuolar-type ATPases.

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.

Sign in / Sign up

Export Citation Format

Share Document