/sup 31/P nuclear magnetic resonance of phosphonic acid analogues of adenosine nucleotides as functions of pH and magnesium ion concentration

Journal Article · Tue Jan 19 04:00:00 EST 1982 · Biochemistry; (United States)

OSTI ID:5655920

Schliselfeld, L H; Burt, C T; Labotka, R J

The /sup 31/P NMR proton-decoupled spectra of ..cap alpha..,..beta..-methylene-ATP (Ap(CH/sub 2/)pp), ..beta..,..gamma..-methylene-ATP (App(CH/sub 2/)p), and ..cap alpha..,..beta..-methylene-ADP (Ap(CH/sub 2/)p) were measured as functions of pH and Mg/sup 2 +/ concentration. Each ATP analogue yielded three resonances: two doublets and one doublet-of-a- doublet. Assignments of resonances were based upon spin-coupling multiplets, their coupling constant magnitudes (24-27 Hz for -P-O-P- and 4-10 Hz for -P-CH/sub 2/-P-), and the magnitude of the chemical shift movement during proton titration or its direction of movement. All phosphonyl resonances are substantially downfield compared to phosphoryl resonances. The chemical shifts of terminal phosphonyl units moved upfield with increasing pH or rising Mg/sup 2 +/ concentration. The chemical shifts of phosphonyl and phosphoryl anhydride plus ester units usually either moved downfield during proton titration and addition of Mg/sup 2 +/ or remained constant. Accurate pK/sub a/' values were readily determined from chemical shift movements as a function of pH; 3.05 +/- 0.04 and 8.80 +/- 0.05 for App(CH/sub 2/)p, 7.34 +/- 0.06 for Ap(CH/sub 2/)pp, and 8.29 +/- 0.02 for AP(CH/sub 2/)p. Addition of Mg/sup 2 +/ or Tris produced an acidic shift of the alkaline pK/sub a/' values. Addition of Mg/sup 2 +/ at pH 7.0 to the nucleotides caused large movements in the chemical shifts of their terminal two phosphorus atoms.

• Research Organization: Univ. of Illinois, Chicago
• OSTI ID: 5655920
• Journal Information: Biochemistry; (United States), Journal Name: Biochemistry; (United States) Vol. 21:2; ISSN BICHA
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ADENOSINE
ADP
ALKALINE EARTH METALS
ATP
CATIONS
CHARGED PARTICLES
ELEMENTS
IONS
MAGNESIUM
METALS
METHYLENE RADICALS
NMR SPECTRA
NUCLEOSIDES
NUCLEOTIDES
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC PHOSPHORUS COMPOUNDS
PH VALUE
PHOSPHONIC ACIDS
RADICALS
RIBOSIDES
SPECTRA
STRUCTURAL CHEMICAL ANALYSIS