scholarly journals Chemical Ligation and Isotope Labeling to Locate Dynamic Effects during Catalysis by Dihydrofolate Reductase

2015 ◽  
Vol 54 (31) ◽  
pp. 9016-9020 ◽  
Author(s):  
Louis Y. P. Luk ◽  
J. Javier Ruiz-Pernía ◽  
Aduragbemi S. Adesina ◽  
E. Joel Loveridge ◽  
Iñaki Tuñón ◽  
...  
Keyword(s):  
Dihydrofolate Reductase ◽  
Isotope Labeling ◽  
Dynamic Effects ◽  
Chemical Ligation

scholarly journals Chemical Ligation and Isotope Labeling to Locate Dynamic Effects during Catalysis by Dihydrofolate Reductase

2015 ◽  
Vol 127 (31) ◽  
pp. 9144-9148 ◽  
Author(s):  
Louis Y. P. Luk ◽  
J. Javier Ruiz-Pernía ◽  
Aduragbemi S. Adesina ◽  
E. Joel Loveridge ◽  
Iñaki Tuñón ◽  
...  
Keyword(s):  
Dihydrofolate Reductase ◽  
Isotope Labeling ◽  
Dynamic Effects ◽  
Chemical Ligation

scholarly journals Minimization of dynamic effects in the evolution of dihydrofolate reductase

2016 ◽  
Vol 7 (5) ◽  
pp. 3248-3255 ◽  
Author(s):  
J. Javier Ruiz-Pernía ◽  
Enas Behiry ◽  
Louis Y. P. Luk ◽  
E. Joel Loveridge ◽  
Iñaki Tuñón ◽  
...  
Keyword(s):  
Dihydrofolate Reductase ◽  
Enzyme Catalysis ◽  
Isotope Labeling ◽  
Conformational Dynamics ◽  
Dynamic Effects ◽  
Powerful Technique ◽  
P Protein

Protein isotope labeling is a powerful technique to probe functionally important motions in enzyme catalysis and can be applied to investigate the conformational dynamics of proteins.

scholarly journals Protein motions and dynamic effects in enzyme catalysis

2015 ◽  
Vol 17 (46) ◽  
pp. 30817-30827 ◽  
Author(s):  
Louis Y. P. Luk ◽  
E. Joel Loveridge ◽  
Rudolf K. Allemann
Keyword(s):  
Dihydrofolate Reductase ◽  
Enzyme Catalysis ◽  
Catalytic Cycle ◽  
Dynamic Effects ◽  
Dynamic Coupling ◽  
Protein Motions ◽  
Catalytic Power

While the full catalytic power of dihydrofolate reductase depends on finely tuning protein motions in each step of the catalytic cycle, dynamic coupling to the actual chemical step is detrimental to catalysis.

scholarly journals Increased Dynamic Effects in a Catalytically Compromised Variant of Escherichia coli Dihydrofolate Reductase

2013 ◽  
Vol 135 (49) ◽  
pp. 18689-18696 ◽  
Author(s):  
J. Javier Ruiz-Pernia ◽  
Louis Y. P. Luk ◽  
Rafael García-Meseguer ◽  
Sergio Martí ◽  
E. Joel Loveridge ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Dihydrofolate Reductase ◽  
Dynamic Effects

Electron probe x-ray microanalysis and electron microscopy of amino acid absorption and transport by the small intestine: inhibition by chemical poisons and correlation to the elemental composition of the epithelial cells

1986 ◽  
Vol 44 ◽  
pp. 134-135
Author(s):  
A. J. Tousimis
Keyword(s):  
Small Intestine ◽  
Amino Acid ◽  
Epithelial Cells ◽  
Elemental Composition ◽  
Isotope Labeling ◽  
Structural Components ◽  
X Ray ◽  
Human Small Intestine ◽  
Transport Studies

The elemental composition of amino acids is similar to that of the major structural components of the epithelial cells of the small intestine and other tissues. Therefore, their subcellular localization and concentration measurements are not possible by x-ray microanalysis. Radioactive isotope labeling: I131-tyrosine, Se75-methionine and S35-methionine have been successfully employed in numerous absorption and transport studies. The latter two have been utilized both in vitro and vivo, with similar results in the hamster and human small intestine. Non-radioactive Selenomethionine, since its absorption/transport behavior is assumed to be the same as that of Se75- methionine and S75-methionine could serve as a compound tracer for this amino acid.

High-resolution gold labeling

1993 ◽  
Vol 51 ◽  
pp. 330-331
Author(s):  
James F. Hainfeld ◽  
Frederic R. Furuya ◽  
Kyra Carbone ◽  
Martha Simon ◽  
Beth Lin ◽  
...  
Keyword(s):  
Dihydrofolate Reductase ◽  
Polypeptide Chain ◽  
External Surface ◽  
Gold Cluster ◽  
Macromolecular Complex ◽  
Gold Compound ◽  
Central Cavity ◽  
Chain Folding ◽  
E Coli ◽  
Chaperonin Groel

A recently developed 1.4 nm gold cluster has been found to be useful in labeling macromolecular sites to 1-3 nm resolution. The gold compound is organically derivatized to contain a monofunctional arm for covalent linking to biomolecules. This may be used to mark a specific site on a structure, or to first label a component and then reassemble a multicomponent macromolecular complex. Two examples are given here: the chaperonin groEL and ribosomes.Chaperonins are essential oligomeric complexes that mediate nascent polypeptide chain folding to produce active proteins. The E. coli chaperonin, groEL, has two stacked rings with a central hole ∽6 nm in diameter. The protein dihydrofolate reductase (DHFR) is a small protein that has been used in chain folding experiments, and serves as a model substrate for groEL. By labeling the DHFR with gold, its position with respect to the groEL complex can be followed. In particular, it was sought to determine if DHFR refolds on the external surface of the groEL complex, or whether it interacts in the central cavity.

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