[NiFe]-Hydrogenase maturation endopeptidase: structure and function

2005 ◽  
Vol 33 (1) ◽  
pp. 108-111 ◽  
Author(s):  
E. Theodoratou ◽  
R. Huber ◽  
A. Böck
Keyword(s):  
Reaction Mechanism ◽  
Substrate Specificity ◽  
Large Subunit ◽  
Cysteine Residue ◽  
Structure And Function ◽  
Metal Centre ◽  
Conformational Switch ◽  
Hydrogenase Maturation ◽  
And Function

Hydrogenase maturation endopeptidases catalyse the terminal step in the maturation of the large subunit of [NiFe]-hydrogenases. They remove a C-terminal extension from the precursor of the subunit, triggering a conformational switch that results in the bridging of the Fe and Ni atoms of the metal centre via the thiolate of a cysteine residue and in closure of the centre. This review summarizes what is known about the structure of the protein, its substrate specificity and its possible reaction mechanism.

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.

Comparison of the structure and function of ribulosebisphosphate carboxylase–oxygenase from a cold-hardy and nonhardy potato species

1981 ◽  
Vol 59 (4) ◽  
pp. 280-289 ◽  
Author(s):  
Norman P. A. Huner ◽  
Jiwan P. Palta ◽  
Paul H. Li ◽  
John V. Carter
Keyword(s):  
Large Subunit ◽  
Structure And Function ◽  
Sulfhydryl Groups ◽  
Relative Mass ◽  
Nitrobenzoic Acid ◽  
Significant Difference ◽  
Ribulosebisphosphate Carboxylase ◽  
Cold Hardy ◽  
And Function ◽  
Kinetics Of

A comparison of ribulosebisphosphate carboxylase–oxygenase from the leaves of the non-acclimated, cold-hardy species, Solanum commersonii, and the nonacclimated, nonhardy species, Solanum tuberosum showed that this enzyme from the two species differed in structure and function. The results of sulfhydryl group titration with 5,5′-dithiobis(2-nitrobenzoic acid) indicated that the kinetics of titration and the number of accessible sulfhydryl groups in the native enzymes were different. After 30 min, the enzyme from the hardy species had 1.7 times fewer sulfhydryl groups titrated than that from the nonhardy species. In the presence of 1% (w/v) sodium dodecyl sulfate, the total number of sulfhydryl groups titratable with 5,5′-dithiobis-(2-nitrobenzoic acid) was the same for both species. However, this denaturant had a differential effect on the kinetics of titration with 5,5′-dithiobis(2-nitrobenzoic acid). Both enzymes had a native molecular weight of about 550 000. The quaternary structures of the two enzymes were similar with the presence of large and small subunits of 54 000 and 14 000, respectively. However, there was more polypeptide of 108 000 – 110 000 present in preparations of the enzyme from S. tuberosum than from S. commersonii. This polypeptide is an apparent dimer of the large subunit on a relative mass basis. The large subunit of the enzyme from S. tuberosum was more sensitive to the absence of reducing agent and was more sensitive to freezing and thawing than the large subunit of the enzyme from S. commersonii. Catalytic properties of both enzymes at 5 and 25 °C indicated no significant difference in the [Formula: see text] at either temperature. However, the Vmax at 5 °C for the enzyme from S. commersonii was 35% higher than that of the enzyme from S. tuberosum. In contrast, the Vmax at 25 °C for the enzyme of the hardy species was 250% lower than that of the enzyme from the nonhardy species.

UDP-glucose dehydrogenase: structure and function of a potential drug target

2010 ◽  
Vol 38 (5) ◽  
pp. 1378-1385 ◽  
Author(s):  
Sigrid Egger ◽  
Apirat Chaikuad ◽  
Kathryn L. Kavanagh ◽  
Udo Oppermann ◽  
Bernd Nidetzky
Keyword(s):  
Sequence Comparison ◽  
Drug Target ◽  
Glucuronic Acid ◽  
Glucose Dehydrogenase ◽  
Enzymatic Reaction ◽  
Cysteine Residue ◽  
Structure And Function ◽  
Eukaryotic Group ◽  
And Function ◽  
Covalent Catalysis

Biosynthesis of the glycosaminoglycan precursor UDP-α-D-glucuronic acid occurs through a 2-fold oxidation of UDP-α-D-glucose that is catalysed by UGDH (UDP-α-D-glucose 6-dehydrogenase). Structure–function relationships for UGDH and proposals for the enzymatic reaction mechanism are reviewed in the present paper, and structure-based sequence comparison is used for subclassification of UGDH family members. The eukaryotic group of enzymes (UGDH-II) utilize an extended C-terminal domain for the formation of complex homohexameric assemblies. The comparably simpler oligomerization behaviour of the prokaryotic group of enzymes (UGDH-I), in which dimeric forms prevail, is traced back to the lack of relevant intersubunit contacts and trimmings within the C-terminal region. The active site of UGDH contains a highly conserved cysteine residue, which plays a key role in covalent catalysis. Elevated glycosaminoglycan formation is implicated in a variety of human diseases, including the progression of tumours. The inhibition of synthesis of UDP-α-D-glucuronic acid using UGDH antagonists might therefore be a useful strategy for therapy.

scholarly journals Structure and function of yeast alcohol dehydrogenase

2000 ◽  
Vol 65 (4) ◽  
pp. 207-227 ◽  
Author(s):  
Svetlana Trivic ◽  
Vladimir Leskovac
Keyword(s):  
Alcohol Dehydrogenase ◽  
Substrate Specificity ◽  
Primary Structure ◽  
Active Site ◽  
Hydride Transfer ◽  
Kinetic Mechanism ◽  
Structure And Function ◽  
Chemical Mechanism ◽  
And Function ◽  
Font Color

1. Introduction 2. Isoenzymes of YADH 3. Substrate specificity 4. Kinetic mechanism 5. Primary structure 6. The active site 7. Mutations in the yeast enzyme 8. Chemical mechanism 9. Binding of coenzymes 10. Hydride transfer <br><br><font color="red"><b> This article has been corrected. Link to the correction <u><a href="http://dx.doi.org/10.2298/JSC0008609E">10.2298/JSC0008609E</a><u></b></font>

scholarly journals Nucleolar Structure and Function in Trypanosomatid Protozoa

Cells ◽  
2019 ◽  
Vol 8 (5) ◽  
pp. 421 ◽  
Author(s):  
Santiago Martínez-Calvillo ◽  
Luis E. Florencio-Martínez ◽  
Tomás Nepomuceno-Mejía
Keyword(s):  
Ribosomal Rna ◽  
Current Knowledge ◽  
Large Subunit ◽  
Nuclear Body ◽  
Structure And Function ◽  
Rrna Genes ◽  
Large Expansion ◽  
Additional Processing ◽  
Rrna Species ◽  
And Function

The nucleolus is the conspicuous nuclear body where ribosomal RNA genes are transcribed by RNA polymerase I, pre-ribosomal RNA is processed, and ribosomal subunits are assembled. Other important functions have been attributed to the nucleolus over the years. Here we review the current knowledge about the structure and function of the nucleolus in the trypanosomatid parasites Trypanosoma brucei, Trypanosoma cruzi and Leishmania ssp., which represent one of the earliest branching lineages among the eukaryotes. These protozoan parasites present a single nucleolus that is preserved throughout the closed nuclear division, and that seems to lack fibrillar centers. Trypanosomatids possess a relatively low number of rRNA genes, which encode rRNA molecules that contain large expansion segments, including several that are trypanosomatid-specific. Notably, the large subunit rRNA (28S-type) is fragmented into two large and four small rRNA species. Hence, compared to other organisms, the rRNA primary transcript requires additional processing steps in trypanosomatids. Accordingly, this group of parasites contains the highest number ever reported of snoRNAs that participate in rRNA processing. The number of modified rRNA nucleotides in trypanosomatids is also higher than in other organisms. Regarding the structure and biogenesis of the ribosomes, recent cryo-electron microscopy analyses have revealed several trypanosomatid-specific features that are discussed here. Additional functions of the nucleolus in trypanosomatids are also reviewed.

scholarly journals Biophysical characterization of the structure and flexibility of the E. Coli ribosome

2019 ◽  
Author(s):  
◽  
Emily Doris Armbruster
Keyword(s):  
Large Subunit ◽  
Small Subunit ◽  
Structure And Function ◽  
23S Rrna ◽  
Internal Cavity ◽  
Macromolecular Complex ◽  
Biophysical Characterization ◽  
E Coli ◽  
Bacterial Ribosome ◽  
And Function

At the discovery of ribosomes by George Palade in 1955 in the first image of the subcellular environment, he described them as "a particulate component of small dimensions (100 to 150 [alpha]) and high density". Subsequently, the ribosome was shown to be the site of protein synthesis, or translation, and thus an essential macromolecular complex for all cells. Ribosomes can have variability from species to species, but the overall structure and function are conserved [66]. Ribosomes are named according to their sedimentation coefficients, a unit of density expressed in Svedbergs (abbreviated S). The three most studied and most prevalent ribosomes are the bacterial 70S, the eukaryotic 80S, and the 55S mitoribosome, which is present in the mitochondrion organelle. The bacterial ribosome serves as a target for many antibiotics and is a model system for investigating the structure and function of this "nanomachine". Despite variations in size, all ribosomes consist of a small and a large subunit that when bound together have an internal cavity that is divided into three sites, named A, P, or E site. The bacterial ribosome has a 30S small subunit, which consists of a 16S rRNA and 21 attached proteins, and a 50S large subunit that is made up of the 23S rRNA, 5S rRNA and 31 proteins. This dissertation discusses the 70S bacterial ribosome, other than when the 80S eukaryotic ribosome is specified.

scholarly journals Transport of organic anions by multidrug resistance-associated protein in the erythrocyte.

2000 ◽  
Vol 47 (3) ◽  
pp. 763-772 ◽  
Author(s):  
B Rychlik ◽  
L Pułaski ◽  
A Sokal ◽  
M Soszyński ◽  
G Bartosz
Keyword(s):  
Multidrug Resistance ◽  
Substrate Specificity ◽  
Atpase Activity ◽  
Natural Environment ◽  
Structure And Function ◽  
Oxidized Glutathione ◽  
Main Subject ◽  
Model Cell ◽  
And Function ◽  
First Time

The active transport of oxidized glutathione and glutathione S-conjugates has been demonstrated for the first time in erythrocytes and this cell remained the main subject of research on the "glutathione S-conjugate pump" for years. Further studies identifled the "glutathione S-conjugate pump" as multidrug resistance-associated protein (MRP). Even though cells overexpressing MRP and isolated MRP provide useful information on MRP structure and function, the erythrocyte remains an interesting model cell for studies of MRP1 in its natural environment, including the substrate specificity and ATPase activity of the protein.

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