Chloroplast F/sub 1/ ATPase has more than three nucleotide binding sites, and 2-azide-ADP or 2-azido-ATP at both catalytic and noncatalytic sites labels the. beta. -subunit

Journal Article · Tue Jun 30 04:00:00 EDT 1987 · Biochemistry; (United States)

OSTI ID:5998190

Xue, Z; Zhou, J M; Melese, T; Cross, R L; Boyer, R D

The photolabeling of chloroplast F/sub 1/ ATPase, following exposure to Mg/sup 2 +/ and 2-azido-ATP and separation from medium nucleotides, results in derivatization of two separate peptide regions of the ..beta.. subunit. Up to 3 mol of the analog can be incorporated per mole of CF/sub 1/, with covalent binding of one moiety or two moieties per ..beta.. subunit that can be either AMP, ADP, or ATP derivatives. These results, the demonstration of noncovalent tight binding of at least four (/sup 3/H)adenine nucleotides to the enzyme and the presence of three ..beta.. subunits per enzyme, point to six potential adenine nucleotide binding sites per molecule. The tightly bound 2-azido nucleotides on CF/sub 1/, found after exposure of the heat-activated and EDTA-treated enzyme to Mg/sup 2 +/ and 2-azido-ATP, differ in their ease of replacement during subsequent hydrolysis of ATP. Some of the bound nucleotides are not readily replaced during catalytic turnover and covalently label one peptide region of the ..beta.. subunit. They are on noncatalytic sites. Other tightly bound nucleotides are readily replaced during catalytic turnover and label another peptide region of the ..beta.. subunit. They are at catalytic sites. No ..cap alpha..-subunit labeling is detected upon photolysis of the bound 2-azido nucleotides. However, one or both of the sites could be at an ..cap alpha..-..beta..-subunit interface with the 2-azido region close to the ..beta.. subunit, or both binding sites may be largely or entirely on the ..beta.. subunit.

• Research Organization: Univ. of California, Los Angeles
• OSTI ID: 5998190
• Journal Information: Biochemistry; (United States), Journal Name: Biochemistry; (United States) Vol. 26:13; ISSN BICHA
• Country of Publication: United States
• Language: English

Related Subjects

14 SOLAR ENERGY
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Photobiological
& Thermochemical Conversion-- (1980-)
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59 BASIC BIOLOGICAL SCIENCES
ACID ANHYDRASES
ADP
ALKALINE EARTH METAL COMPOUNDS
ATP
ATP-ASE
AUTORADIOGRAPHY
AZIDO COMPOUNDS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BIOCHEMISTRY
CATIONS
CELL CONSTITUENTS
CHARGED PARTICLES
CHEMICAL REACTIONS
CHEMISTRY
CHLOROPLASTS
CHROMATOGRAPHY
DAYS LIVING RADIOISOTOPES
DERIVATIZATION
ELECTROPHORESIS
ENZYME ACTIVITY
ENZYMES
HYDROLASES
IONS
ISOTOPES
LABELLED COMPOUNDS
LIGASES
LIGHT NUCLEI
LIQUID COLUMN CHROMATOGRAPHY
MAGNESIUM COMPOUNDS
NUCLEI
NUCLEOTIDES
ODD-ODD NUCLEI
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PHOSPHOHYDROLASES
PHOSPHORUS 32
PHOSPHORUS ISOTOPES
RADIOISOTOPES
SEPARATION PROCESSES
TRITIUM COMPOUNDS