/sup 1/H nuclear magnetic resonance studies of the conformation of an ATP analogue at the active site of Na,K-ATPase from kidney medulla

Journal Article · Tue Jun 28 04:00:00 EDT 1988 · Biochemistry; (United States)

OSTI ID:6768575

MacD Stewart, J M; Grisham, C M

/sup 1/H nuclear magnetic relaxation measurements have been used to determine the three-dimensional conformation of an ATP analogue, Co(NH/sub 3/)/sub 4/ATP, at the active site of sheep kidney Na,K-ATPase. Previous studies have shown that Co(NH/sub 4/)/sub 4/ATP is a competitive inhibitor with respect to MnATP for the Na,K-ATPase and that Mn/sup 2 +/ bound to a single, high-affinity site on the ATPase can be an effective paramagnetic probe for nuclear relaxation studies of the Na-K-ATPase. From the paramagnetic effect of Mn/sup 2 +/ bound to the APTase on the longitudinal relaxation rates of the protons of Co(NH/sub 3/)/sub 4/ATP at the substrate site (at 300 and 361 MHz), Mn-H distances to seven protons on the bound nucleotide were determined. Taken together with previous /sup 31/P nuclear relaxation data, these measurements are consistent with a single nucleotide conformation at the active site. The nucleotide adopts a bent configuration, in which the triphosphate chain lies nearly parallel to the adenine moiety. The glycosidic torsion angle is 35/sup 0/, and the conformation of the ribose ring is slightly N-type. The bound Mn/sup 2 +/ lies above and in the plane of the adenine ring. The distances from Mn/sup 2 +/ to N/sub 6/ and N/sub 7/ are too large for first coordination sphere complexes but are appropriate for second-sphere complexes involving, for example, intervening hydrogen-bonded water molecules. The NMR data also indicate that the structure of the bound ATP analogue is independent of the conformational state of the enzyme.

• Research Organization: Univ. of Virginia, Charlottesville (USA)
• OSTI ID: 6768575
• Journal Information: Biochemistry; (United States), Journal Name: Biochemistry; (United States) Vol. 27:13; ISSN BICHA
• Country of Publication: United States
• Language: English

Related Subjects

550601* -- Medicine-- Unsealed Radionuclides in Diagnostics
62 RADIOLOGY AND NUCLEAR MEDICINE
ACID ANHYDRASES
ALKALI METAL COMPOUNDS
ATP
ATP-ASE
BARYONS
BODY
CATIONS
CHARGED PARTICLES
CONFORMATIONAL CHANGES
ELEMENTARY PARTICLES
ENZYMES
FERMIONS
HADRONS
HYDROLASES
IONS
ISOTOPES
KIDNEYS
LIGHT NUCLEI
MAGNETIC RESONANCE
NUCLEAR MAGNETIC RESONANCE
NUCLEI
NUCLEONS
NUCLEOTIDES
ODD-EVEN NUCLEI
ORGANIC COMPOUNDS
ORGANS
PHOSPHOHYDROLASES
PHOSPHORUS 31
PHOSPHORUS ISOTOPES
POTASSIUM COMPOUNDS
PROTONS
RESONANCE
SODIUM COMPOUNDS
STABLE ISOTOPES