scholarly journals The eucaryotic aminoacyl-tRNA synthetase complex: suggestions for its structure and function.

1984 ◽  
Vol 99 (2) ◽  
pp. 373-377 ◽  
Author(s):  
M P Deutscher
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Structural Similarity ◽  
Trna Synthetase ◽  
Aminoacyl Trna Synthetase ◽  
Trna Synthetases ◽  
Membrane Bound ◽  
And Function ◽  
Molecular Weight Form

Aminoacyl-tRNA synthetases from eucaryotic cells generally are isolated as high molecular weight complexes comprised of multiple synthetase activities, and often containing other components as well. A model is proposed for the synthetase complex in which hydrophobic extensions on the proteins serve to maintain them in their high molecular weight form, but are not needed for catalytic activity. The structural similarity of these enzymes to certain membrane-bound proteins, and its implications for synthetase localization and function in vivo, are discussed.

scholarly journals The interrelations between high- and low-molecular-weight forms of normal and mutant (Krabbe-disease) galactocerebrosidase

1980 ◽  
Vol 189 (1) ◽  
pp. 9-15 ◽  
Author(s):  
Yoav Ben-Yoseph ◽  
Melinda Hungerford ◽  
Henry L. Nadler
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Specific Activity ◽  
Polyacrylamide Gel Electrophoresis ◽  
Active Form ◽  
Sodium Dodecyl ◽  
Krabbe Disease ◽  
Low Molecular Weight ◽  
Molecular Weight Form

Galactocerebrosidase (β-d-galactosyl-N-acylsphingosine galactohydrolase; EC 3.2.1.46) activity of brain and liver preparations from normal individuals and patients with Krabbe disease (globoid-cell leukodystrophy) have been separated by gel filtration into four different molecular-weight forms. The apparent mol.wts. were 760000±34000 and 121000±10000 for the high- and low-molecular-weight forms (peaks I and IV respectively) and 499000±22000 (mean±s.d.) and 256000±12000 for the intermediate forms (peaks II and III respectively). On examination by sodium dodecyl sulphate/polyacrylamide-gel electrophoresis, the high- and low-molecular-weight forms revealed a single protein band with a similar mobility corresponding to a mol.wt. of about 125000. Antigenic identity was demonstrated between the various molecular-weight forms of the normal and the mutant galactocerebrosidases by using antisera against either the high- or the low-molecular-weight enzymes. The high-molecular-weight form of galactocerebrosidase was found to possess higher specific activity toward natural substrates when compared with the low-molecular-weight form. It is suggested that the high-molecular-weight enzyme is the active form in vivo and an aggregation process that proceeds from a monomer (mol.wt. approx. 125000) to a dimer (mol.wt. approx. 250000) and from the dimer to either a tetramer (mol.wt. approx. 500000) or a hexamer (mol.wt. approx. 750000) takes place in normal as well as in Krabbe-disease tissues.

scholarly journals An Expanded Genetic Code in Candida albicans To Study Protein-Protein Interactions In Vivo

2013 ◽  
Vol 12 (6) ◽  
pp. 816-827 ◽  
Author(s):  
Silke Palzer ◽  
Yannick Bantel ◽  
Franziska Kazenwadel ◽  
Michael Berg ◽  
Steffen Rupp ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Candida Albicans ◽  
Amino Acid ◽  
Genetic Code ◽  
Molecular Interactions ◽  
Trna Synthetase ◽  
Aminoacyl Trna Synthetase ◽  
Content Type ◽  
Suppressor Trna

ABSTRACT For novel insights into the pathogenicity of Candida albicans , studies on molecular interactions of central virulence factors are crucial. Since methods for the analysis of direct molecular interactions of proteins in vivo are scarce, we expanded the genetic code of C. albicans with the synthetic photo-cross-linking amino acid p -azido- l -phenylalanine (AzF). Interacting molecules in close proximity of this unnatural amino acid can be covalently linked by UV-induced photo-cross-link, which makes unknown interacting molecules available for downstream identification. Therefore, we applied an aminoacyl-tRNA synthetase and a suppressor tRNA pair ( Ec TyrtRNA CUA ) derived from Escherichia coli , which was previously reported to be orthogonal in Saccharomyces cerevisiae . We further optimized the aminoacyl-tRNA synthetase for AzF (AzF-RS) and Ec TyrtRNA CUA for C. albicans and identified one AzF-RS with highest charging efficiency. Accordingly, incorporation of AzF into selected model proteins such as Tsa1p or Tup1p could be considerably enhanced. Immunologic detection of C-terminally tagged Tsa1p and Tup1p upon UV irradiation in a strain background containing suppressor tRNA and optimized AzF-RS revealed not only the mutant monomeric forms of these proteins but also higher-molecular-weight complexes, strictly depending on the specific position of incorporated AzF and UV excitation. By Western blotting and tandem mass spectrometry, we could identify these higher-molecular-weight complexes as homodimers consisting of one mutant monomer and a differently tagged, wild-type version of Tsa1p or Tup1p, respectively, demonstrating that expanding the genetic code of C. albicans with the unnatural photo-cross-linker amino acid AzF and applying it for in vivo binary protein interaction analyses is feasible.

scholarly journals Insights into structure, affinity, specificity, and function of GAG-protein interactions through the chemoenzymatic preparation of defined sulfated oligohyaluronans

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Jürgen Schiller ◽  
Katharina Lemmnitzer ◽  
Jan-Niklas Dürig ◽  
Jörg Rademann
Keyword(s):  
Molecular Weight ◽  
Protein Binding ◽  
High Molecular Weight ◽  
Protein Interactions ◽  
Connective Tissues ◽  
Gag Protein ◽  
Synthetic Oligosaccharides ◽  
And Function

Abstract High amounts of glycosaminoglycans (GAG) such as hyaluronan (HA) occur in connective tissues. There is nowadays increasing evidence that a “sulfation code” exists which mediates numerous GAG functions. High molecular weight and inhomogeneity of GAG, however, aggravated detailed studies. Thus, synthetic oligosaccharides were urgently required. We will review here chemoenzymatic and analytic strategies to provide defined sulfated and anomerically modified GAG oligosaccharides of the HA type. Representative studies of protein/GAG interactions by (bio)chemical and biophysical methods are reported yielding novel insights into GAG-protein binding. Finally, the biological conclusions and in vivo applications of defined sulfated GAG oligosaccharides will be discussed.

Linear and high-molecular-weight poly-porphyrins for efficient photodynamic therapy

2021 ◽  
Author(s):  
Nan Zheng ◽  
Xiahui Li ◽  
Shangwei Huangfu ◽  
Kangkai Xia ◽  
Ruofei Yue ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Photodynamic Therapy ◽  
Quantum Yield ◽  
Singlet Oxygen ◽  
High Molecular Weight ◽  
Linear Poly ◽  
High Molecular Weight Poly

A linear poly-porphyrin with high Mw and conjugated by PEG and acetazolamide was developed with enhanced singlet oxygen quantum yield, improved photo-toxicity and excellent in vivo photodynamic therapy.

Sign in / Sign up

Export Citation Format

Share Document