Evidence for a single transition state in the transfer of the phosphoryl group (-PO32-) to nitrogen nucleophiles from pyridinio-N-phosphonates

1984 ◽  
Vol 106 (24) ◽  
pp. 7591-7596 ◽  
Author(s):  
Nicholas Bourne ◽  
Andrew Williams
Keyword(s):  
Transition State ◽  
Phosphoryl Group ◽  
Single Transition ◽  
Nitrogen Nucleophiles

Phosphotransfer and Nucleotidyltransfer

2007 ◽  
Author(s):  
Perry A. Frey ◽  
Adrian D. Hegeman
Keyword(s):  
Transition State ◽  
Molecular Mechanisms ◽  
Enzymatic Reaction ◽  
Covalent Bond ◽  
Phosphoryl Group ◽  
Dissociative Mechanism ◽  
Chemical Mechanisms ◽  
Cellular Processes ◽  
Nucleic Acid Biosynthesis ◽  
Transfer Mechanisms

Phosphotransferases, phosphatases, and nucleotidyltransferases catalyze nucleophilic substitution at phosphorus. They constitute a dominant class of enzymes in intermediary metabolism, energy transduction, nucleic acid biosynthesis and processing, and regulation of many cellular processes, including replication, cellular development, and apoptosis. The mechanisms of the action of these enzymes have been studied intensively at several levels, ranging from the biosynthesis of metabolites and nucleic acids to unmasking signaling networks to elucidating the molecular mechanisms of catalysis. We focus on the chemical mechanisms of the reactions of biological phosphates. More than 40 years of research on this chemistry reveals that the mechanisms can be grouped into two classes: the phosphoryl group (PO3−) transfer mechanisms and the nucleotidyl or alkylphosphoryl group (ROPO2−) transfer mechanisms. Because the fundamental chemical mechanisms of these reactions are not treated in textbooks, we begin by considering this chemistry and then move on to the enzymatic reaction mechanisms. Phosphomonoesters, phosphoanhydrides, and phosphoramidates undergo substitution at phosphorus by transfer of the phosphoryl (PO3–) group, that is, by P—O and P—N cleavage. The current description of a typical phosphoryl group transfer mechanism is one in which the phosphoryl donor and acceptor interact weakly with the phosphoryl group in flight in a transition state in which the total bonding to phosphorus is decreased relative to the ground state. The bonding is weak between phosphorus and the leaving group R–X and between phosphorus and the accepting group Y in the transition state of. Because of decreased bonding to phosphorus, this is a loose transition state that has been described as dissociative. The latter should not be confused with the dissociative mechanism, which is considered later. To avoid confusion, we use the term loose transition state. Detailed studies indicate that the bonding denoted by the dashed lines in represents partial covalency on the order of 10% to 20% of the strength of a full covalent bond, or a bond order of 0.1 to 0.2.

Single transition state for sulfonato group (SO3) transfer between pyridine nucleophiles

1985 ◽  
Vol 107 (14) ◽  
pp. 4327-4331 ◽  
Author(s):  
Nicholas Bourne ◽  
Andrew Hopkins ◽  
Andrew Williams
Keyword(s):  
Transition State ◽  
Single Transition

scholarly journals Theoretical study on pegylation reaction mechanisms of IFN-α-2a, IFN-α-2b and IFN-β-1a

2017 ◽  
Vol 82 (7-8) ◽  
pp. 841-850
Author(s):  
Mohammad Taqavian ◽  
Daryoush Abedi ◽  
Fatemeh Zigheimat ◽  
Leila Zeidabadinejad
Keyword(s):  
Polyethylene Glycol ◽  
Reaction Mechanism ◽  
Dft Calculations ◽  
Transition State ◽  
Reaction Mechanisms ◽  
Theoretical Study ◽  
Computational Study ◽  
Single Transition ◽  
Experimental Works ◽  
Ab Initio And Dft

Ab initio and DFT calculations have been carried out to study the reaction mechanism between interferons (IFNs) ?-2a, ?-2b and ?-1a and polyethylene glycol (PEG) group. The calculations show that the mechanisms are concerted, in agreement with the results of experimental works. However, although it appears that there is one single transition state, the characteristics of its structure reveal a very synchronous reaction mechanism. The reactions are clearly exothermic and as well have feasible activation energies. Our computational study shows that the lowest transition state energies are related to Lys 134, His 34 and Met 1 of IFN-?-2a, IFN-?-2b and IFN-?-1a, respectively.

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