Synthesis of nucleoside tetraphosphates and dinucleoside pentaphosphates from nucleoside phosphoropiperidates via the activation of P(V)N bond

Pentaphosphorylation via the Anhydride of Dihydrogen Pentametaphosphate: Access to Nucleoside Hexa- and Heptaphosphates and Study of Their Interaction with Ribonuclease A

Pentametaphosphate is the little studied cyclic pentamer of the metaphosphate ion, [PO3]5 5-. We show that the doubly protonated form of this pentamer can be selectively dehydrated to provide the anhydride [P5O14]3- (1). This trianion is the well-defined condensed phosphate component of a novel reagent for attachment of a pentaphosphate chain to biomolecules all in one go. Here, we demonstrate by extending adenosine monophosphate (AMP) and uridine monophosphate (UMP) to their corresponding nucleoside hexaphosphates, while adenosine diphosphate (ADP) and uridine diphosphate (UDP) are phosphate chain-extended to the corresponding nucleoside heptaphosphates. Such constructs are of interest for their potential biological function with respect to RNA-processing enzymes. Thus, we go on to investigate in detail the interaction of the polyanionic constructs with ribonuclease A, a model protein containing a polycationic active site and for which X-ray crystal structures are relatively straightforward to obtain. This work presents a combined experimental and quantum chemical approach to understanding the interactions of RNase A with the new nucleoside hexa- and heptaphosphate constructs.

Beyond Triphosphates: Reagents and Methods for Chemical Oligophosphorylation

Oligophosphates play essential roles in biochemistry, and considerable research has been directed toward the synthesis of both naturally occurring oligophosphates and their synthetic analogues. Greater attention has been given to mono-, di-, and triphosphates, as these are present in higher concentrations biologically and easier to synthesize. However, extended oligophosphates have potent biochemical roles, ranging from blood coagulation to HIV drug resistance. Sporadic reports have slowly built a niche body of literature related to the synthesis and study of extended oligophosphates, but newfound interests and developments have the potential to rapidly expand this field. Here we report on current methods to synthesize oligophosphates longer than triphosphates and comment on the most important future directions for this area of research. The state of the art has provided fairly robust methods for synthesizing nucleoside 5'-tetra- and pentaphosphates as well as dinucleoside 5',5'-oligophosphates. Future research should endeavor to push such syntheses to longer oligophosphates while developing synthetic methodologies for rarer morphologies such as 3'-nucleoside oligophosphates, polyphosphates, and phosphonate/thiophosphate analogues of these species.

Fluorescently Labelled ATP Analogues for Direct Monitoring of Ubiquitin Activation

Simple and robust assays to monitor enzymatic ATP cleavage with high efficiency in real‐time are scarce. To address this shortcoming, we developed fluorescently labelled adenosine tri‐, tetra‐ and pentaphosphate analogues of ATP. The novel ATP analogues bear — in contrast to earlier reports — only a single acridone‐based dye at the terminal phosphate group. The dye's fluorescence is quenched by the adenine component of the ATP analogue and is restored upon cleavage of the phosphate chain and dissociation of the dye from the adenosine moiety. Thereby the activity of ATP‐cleaving enzymes can be followed in real‐time. We demonstrate this proficiency for ubiquitin activation by the ubiquitin‐activating enzymes UBA1 and UBA6 which represents the first step in an enzymatic cascade leading to the covalent attachment of ubiquitin to substrate proteins, a process that is highly conserved from yeast to humans. We found that the efficiency to serve as cofactor for UBA1/UBA6 very much depends on the length of the phosphate chain of the ATP analogue: triphosphates are used poorly while pentaphosphates are most efficiently processed. Notably, the novel pentaphosphate‐harbouring ATP analogue supersedes the efficiency of recently reported dual‐dye labelled analogues and thus, is a promising candidate for broad applications.

Synthetic Strategies for Dinucleotides Synthesis

Dinucleoside 5′,5′-polyphosphates (DNPs) are endogenous substances that play important intra- and extracellular roles in various biological processes, such as cell proliferation, regulation of enzymes, neurotransmission, platelet disaggregation and modulation of vascular tone. Various methodologies have been developed over the past fifty years to access these compounds, involving enzymatic processes or chemical procedures based either on P(III) or P(V) chemistry. Both solution-phase and solid-support strategies have been developed and are reported here. Recently, green chemistry approaches have emerged, offering attracting alternatives. This review outlines the main synthetic pathways for the preparation of dinucleoside 5′,5′-polyphosphates, focusing on pharmacologically relevant compounds, and highlighting recent advances.

Straightforward Ball-Milling Access to Dinucleoside 5',5'-Polyphosphates via Phosphorimidazolide Intermediates

A solvent-assisted mechanochemical approach to access symmetrical and mixed dinucleoside 5,5'-polyphosphates is reported. Under ball-milling conditions, nucleoside 5'-monophosphates were quantitatively activated using 1,1'-carbonyldiimidazole, forming their phosphorimidazolide derivatives. The addition of a nucleoside 5'-mono-, di- or triphosphate directly led to the formation of the corresponding dinucleotides. Benefits of the reported one-pot method include the use of unprotected nucleotides in their sodium or acid form, activation by the eco-friendly 1,1'-carbonyldiimidazole, non-dry conditions, short reaction time, high conversion rates, and easy setup and purification. This work offers new perspectives for the synthesis of nucleotide conjugates and analogues, combining the phosphorimidazolide approach and milling conditions.

Synthesis of Nucleoside-5'-O-Tetraphosphates from Activated Trimetaphosphate and Nucleoside-5'-O-Monophosphates

This article describes a straight-forward chemical method for the synthesis of nucleoside-5'-O-tetraphosphates, such as cytosine-, guanosine-, adenosine-, and uridine-5'-O-tetraphosphates, starting from the corresponding nucleoside monophosphates and trimetaphosphate, a readily available and inexpensive starting material. The procedure involves reacting the tri(tetrabutylammonium) salt of trimetaphosphate with mesitylenesulfonyl chloride and N-methylimidazole. The resulting activated cyclic trimetaphosphate is reacted with the tetrabutylammonium salts of nucleoside monophosphates. After quenching the reaction with buffer and high-performance liquid chromatography purification, the desired nucleoside-5'-O-tetraphosphates were obtained in yields of 84% to 86%. © 2018 by John Wiley & Sons, Inc.