The Hydrolysis of 5′-CAP Dinucleotide Analogs: Catalysis by Bi- and Terpyridine Complexes of Cu²⁺ and Zn²⁺ Ions

Abstract

The kinetics of the hydrolysis of P¹-(7-methylguanosinyl-5 ′) P³-(guanosinyl-5 ′) triphosphate (m⁷GpppG), P¹-(7-methylguanosinyl-5 ′) P⁴-(guanosinyl-5 ′) tetraphosphate (m⁷GppppG), and diadenosine 5 ′, 5 ′ ^′-P¹,P³ -triphosphate (ApppA) in the presence of several Cu²⁺ or Zn²⁺ ions complexed with bi- or terpyridine has been studied at pH 8.0 and 60 °C. Time-dependent product distributions at various metal complex concentrations have been determined by capillary zone electrophoresis and reversed-phase high performance liquid chromatography. The results show that the predominant hydrolytic reaction is the cleavage of 5 ′,5 ′-oligophosphate bridge, with Cu²⁺ complexes being approximately 15-fold more efficient catalysts than Zn²⁺ chelates. In addition, the effect of metal ions complexes at pH 7.0 and 8.0 on the imidazole ring opening in m⁷Gua mononucleotides has been studied. The influence of Cu²⁺ complexes on imidazole ring cleavage of mononucleotides is modest, whereas Zn²⁺ complexes are almost inactive.

Keywords:

• mRNA 5′-cap analogs
• hydrolysis
• kinetics
• rate constants

Acknowledgments

We thank Professor Edward Darżynkiewicz (Warsaw University, Poland) and Professor Harri Lönnberg (University of Turku, Finland) as well as their research groups for synthesis of the cap analogs; we also thank Professor Harri Lönnberg and Professor T. Krogulec (University of Białystok, Poland) for providing access to high performance liquid chromatography and capillary electrophoresis apparatus. We particularly thank Dr. Satu Mikkola (University of Turku, Finland) for fruitful discussions.

Notes

^aValues reported previously by Valakoski et al.^{[ 17 ]}