Estimation of cytoplasmic free Mg2+ levels and phosphorylation potentials in mung bean root tips by in vivo 31P NMR spectroscopy

Yoshiaki Yazaki, Norio Asukagawa, Yutaka Ishikawa, Eiji Ohta, Makoto Sakata

Research output: Contribution to journalArticle

75 Citations (Scopus)

Abstract

The cytoplasmic [MgATP]/[ATP]free ratios, free Mg2+ concentrations, and phosphorylation potentials in mung bean [Vigna mungo (L.) Hepper] root tip cells were investigated by 31P nuclear magnetic resonance spectroscopy. 31P NMR spectra show well defined peaks due to G6P, cytoplasmic Pi, vacuolar Pi, ATP, UDP-glucose and nicotinamide adenine nucleotides. The concentrations of phosphorus metabolites were determined from quantitative 31P NMR spectra. The [MgATP]/[ATP]free ratio was 9.45. Accordingly, about 90% of the cytoplasmic ATP was complexed to Mg2+. Utilizing the dissociation constant (Kd) determined for MgATP, the cytoplasmic free Mg2+ concentration was estimated to be 0.4mM. The NMR-derived phosphorylation potential, [ATP]/([ADP][Pi]), was 960 M-1. The sodium azide treatment decreased the [ATP]/[ADP] ratio and the phosphorylation potential, and increased the [Mg2+]free. Metabolic inhibition may have been enhanced by an increase in [Mg2+free and a decrease in the free energy change for ATP hydrolysis, which resulted due to a decrease in the ATP level.

Original languageEnglish
Pages (from-to)919-924
Number of pages6
JournalPlant and Cell Physiology
Volume29
Issue number6
Publication statusPublished - 1988 Sep

Fingerprint

Mung Bean
Phosphorylation
Meristem
mung beans
Pi
root tips
Nuclear magnetic resonance spectroscopy
nuclear magnetic resonance
Administrative data processing
nuclear magnetic resonance spectroscopy
Spectroscopy
phosphorylation
Magnetic Resonance Spectroscopy
Adenosine Triphosphate
spectroscopy
Nuclear magnetic resonance
Roots
nicotinamide
Decrease
sodium azide

Keywords

  • 31P NMR
  • ATP
  • Free Mg2+
  • MgATP
  • Mung bean (Vigna mungo)
  • Phosphorylation potential

ASJC Scopus subject areas

  • Statistics, Probability and Uncertainty
  • Applied Mathematics
  • Ecology
  • Cell Biology
  • Physiology
  • Plant Science

Cite this

Estimation of cytoplasmic free Mg2+ levels and phosphorylation potentials in mung bean root tips by in vivo 31P NMR spectroscopy. / Yazaki, Yoshiaki; Asukagawa, Norio; Ishikawa, Yutaka; Ohta, Eiji; Sakata, Makoto.

In: Plant and Cell Physiology, Vol. 29, No. 6, 09.1988, p. 919-924.

Research output: Contribution to journalArticle

Yazaki, Yoshiaki ; Asukagawa, Norio ; Ishikawa, Yutaka ; Ohta, Eiji ; Sakata, Makoto. / Estimation of cytoplasmic free Mg2+ levels and phosphorylation potentials in mung bean root tips by in vivo 31P NMR spectroscopy. In: Plant and Cell Physiology. 1988 ; Vol. 29, No. 6. pp. 919-924.
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