Journal ArticleDOI
Demonstration of two reaction pathways for the aminoacylation of tRNA. Application of the pulsed quenched flow technique.
Alan R. Fersht,Ross Jakes +1 more
TLDR
A rapid mixing and quenching device is described which operates efficiently in the range of 150 msec to several minutes as well as the usual time scale of 5-150 msec of the conventional apparatus to measure the initial rate of acylation by the tyrosyl-tRNA synthetase of Escherichia coli during the first turnover of the enzyme.Abstract:
A rapid mixing and quenching device is described which operates efficiently in the range of 150 msec to several minutes as well as the usual time scale of 5-150 msec of the conventional apparatus. This has been used to measure the initial rate of acylation of tRNATyr by the tyrosyl-tRNA synthetase of Escherichia coli during the first turnover of the enzyme, and also the rate constants of the partial reactions of amino acid activation and transfer to the tRNA. It is shown that at saturating conenctration of tRNA the reaction proceeds by a ternary complex mechanism. The rate-determining step is either the aminoacyltion process or a step preceding it. At low concentrations of tRNA the reaction proceeds by the stepwise process of formation of tyrosyl adenylate followed by acylation of the tRNA. The rate constants for these partial reactions are faster than that for the ternary complex reaction. But the prior binding of tRNA greatly decreases the rate of tyrosyl adenylate formation. Both pathways are probably important at physiological concentrations. 88% of the tyrosine from the tyrosyl adenylate complex is transferred to tRNA. The presence of added tyrosine and ATP reduces this to 78%. However, the addition of aliquots of ATP to a mixture of enzyme, tyrosine, and a saturating concentration of tRNA (i.e., ternary complex conditions) leads to at least 0.97 mol of tRNA being acylated/mol of ATP hydrolyzed. Trapping experiments show that the 12% of adenylated that is not transferred to tRNA is hydrolyzed on the enzyme rather than expelled into solution.read more
Citations
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Journal ArticleDOI
Hydrogen bonding and biological specificity analysed by protein engineering
Alan R. Fersht,Jian-Ping Shi,J.W. Knill-Jones,Denise M. Lowe,Anthony J. Wilkinson,David M. Blow,Peter Brick,Paul Carter,Mary M.Y. Waye,Greg Winter +9 more
TL;DR: The role of complementary hydrogen bonding as a determinant of biological specificity has been examined by protein engineering of the tyrosyl-tRNA synthetase and the presence of an unpaired and charged donor or acceptor weakens binding energy.
Journal ArticleDOI
The folding of an enzyme: I. Theory of protein engineering analysis of stability and pathway of protein folding
TL;DR: In this article, a simple protein engineering approach to the problem of the stability and pathway of protein folding is outlined for the simple case of phi = 0 or 1, the most common values, since effects of disruption of structure can cancel out.
Book ChapterDOI
Hydrogen Bonding and Chemical Reactivity
Frank Hibbert,John Emsley +1 more
TL;DR: The role of hydrogen bonding in catalysis has been discussed in this article, although mainly in terms of the salicylate ion as a leaving group, and it seems likely that this will herald other systems where the role of a strong hydrogen bond may serve as the key step in a catalytic process.
BookDOI
Ion Channel Reconstitution
TL;DR: This chapter discusses the physical nature of Planar Bilayer Membrane Electrostatics and the Shapes of Channel Proteins, as well as analysis and Chemical Modification of Bacterial Porins.
Journal ArticleDOI
Redesigning enzyme structure by site-directed mutagenesis: tyrosyl tRNA synthetase and ATP binding
TL;DR: A general method for systematically replacing amino acids in an enzyme is described, which allows analysis of their molecular roles in substrate binding or catalysis and could eventually lead to the engineering of new enzymatic activities.
References
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Journal ArticleDOI
Kinetic proofreading: a new mechanism for reducing errors in biosynthetic processes requiring high specificity.
TL;DR: The specificity with which the genetic code is read in protein synthesis, and with which other highly specific biosynthetic reactions take place, can be increased above the level available from free energy differences in intermediates or kinetic barriers by a process defined here as kinetic proofreading.
Journal ArticleDOI
An improved method for thin-layer chromatography of nucleotide mixtures containing32P-labeled orthophosphate
TL;DR: Developing poly(ethylene)imine cellulose thin layers with phosphate solutions gives improved resolution of complex mixtures of nucleotides and minimizes the tailing of highly radioactive orthophosphate present in the mixtures and thus facilitates chromatographic analysis of crude acid extracts of phosphate-labeled bacteria.
Journal ArticleDOI
Transfer Ribonucleic Acid-induced Hydrolysis of Valyladenylate Bound to Isoleucyl Ribonucleic Acid Synthetase
Anne Norris Baldwin,Paul Berg +1 more
TL;DR: The net reaction observed is a tRNA-induced hydrolysis of valyl-AMP, and any alteration of the tRNA which destroys the isoleucine acceptor activity also destroys the ability of thetRNA to induce the hydrolyzing of the enzyme-bound valyladenylate.
Journal ArticleDOI
Purification and physical characterization of tyrosyl ribonucleic acid synthetases from Escherichia coli and Bacillus subtilis.
Richard Calendar,Paul Berg +1 more
Journal ArticleDOI
Transient State Phosphate Production in the Hydrolysis of Nucleoside Triphosphates by Myosin
TL;DR: The course of presteady-state phosphate liberation in the hydrolysis of nucleoside triphosphates by myosin was studied using a chemical-quench flow apparatus and several important features of the mechanism, notably the nature of the early burst and of activation by actin, are poorly understood.