Partial Resolution of the Enzymes Catalyzing Photophosphorylation

Vambutas, Vida; Racker, Efraim

doi:10.1016/s0021-9258(18)97376-x

Cited by 355 publications

(34 citation statements)

References 21 publications

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“…The dithiothreitol stimulation saturates at ~50 mM. In contrast to higher plant ATPases (Vambutas & Racker, 1965), the C. reinhardi enzyme is not activated by protease digestion or heat (data not shown). The activity of the enzyme at 37 °C, after being incubated at 65 °C for 0-5 min, is unaltered (data not shown).…”

Section: Resultsmentioning

confidence: 86%

“…In all instances where it has been examined, the enzyme appears to contain five nonidentical subunits, although the stoichiometry of the subunit composition is still disputed (Baird & Hammes, 1979). In most cases, with the exception of the E. gracilis enzyme (Chang & Kahn, 1966), the ATPase activity of the enzyme is latent and is only expressed after activation by either proteolysis, heat treatment, or incubation of the enzyme in the presence of a high concentration of thiol reducing agents (Farron & Racker, 1970;Petrack et al, 1965;Vambutas & Racker, 1965). The soluble enzyme is usually assayed as a CaATPase (McCarty & Racker, 1968), although Nelson et al (1972) have described a MgATPase activity for the enzyme isolated from spinach when measured in bicarbonate or maleate buffers.…”

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confidence: 99%

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Isolation, purification, and characterization of coupling factor 1 from Chlamydomonas reinhardi

Selman-Reimer¹,

Merchant²,

Selman³

1981

Biochemistry

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Chloroplast thylakoid particles were prepared from wild-type Chlamydomonas reinhardi by gentle sonication. These particles catalyzed phenazine methosulfate dependent photophosphorylation with rates ranging from 300 to 700 mumol of adenosine 5'-triphosphate (ATP) formed (mg of chlorophyll)-1h-1. Photophosphorylation was not sensitive to tentoxin but was sensitive to an anticoupling factor 1 (CF1) antiserum preparation made against spinach CF1. The C. reinhardi chloroplast CF1 was isolated from thylakoid particles by either chloroform or ethylenediaminetraacetic acid extraction. The former enzyme appeared to be missing the gamma subunit and did not reconstitute with partially resolved thylakoid particles. The latter enzyme reconstituted with partially resolved particles and had a specific activity at 37 degrees C of 2-5 umol of ATP hydrolyzed (mg of protein)-1 min-1. The enzyme utilized both MnATP and MgATP. CaATP was a poor substrate, and SrATP was not hydrolyzed. The enzyme was not activated by heat or proteolysis but was stimulated approximately 2-fold by 50 mM dithiothreitol. Alcohols reversibly stimulated the ATPase activity of the enzyme 5-25-fold. Ethanol, 20%, dramatically lowered the temperature optimum from approximately 75 to approximately 45 degrees C and slightly lowered the pH optimum from 8.5 to 8.2. Ethanol had no effect on the activation energy of the ATPase reaction (17 +/- 1.7 kcal/mol). The kinetics of the ATPase reaction catalyzed by the C. reinhardi enzyme are complex. Both free divalent cations and divalent cation ATP inhibited the activity of the enzyme. The apparent Km for MgTAP (55 uM free Mg2+) was approximately 0.2 mM.

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Section: Resultsmentioning

confidence: 86%

mentioning

confidence: 99%

Isolation, purification, and characterization of coupling factor 1 from Chlamydomonas reinhardi

Selman-Reimer¹,

Merchant²,

Selman³

1981

Biochemistry

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“…ATPase activity of the solubilized CF, is also very poor, but it can be activated by trypsin (Vambutas & Racker, 1965; 1 Abbreviations: CF,, chloroplast coupling factor 1; OG, octyl /3-dglucopyranoside; tricine, 7V-[tris(hydroxymethyl)methyI]glycine; AMP-P(NH)P, 5'-adenylyl imidodiphosphate; quercetin, 3,3',4',5,7-pentahydroxyflavone; phloridzin, l-[2-(/3-D-glucopyranosyloxy)-4,6-dihydroxyphenyl]-3-(4-hydroxyphenyl)-l-propanone; cmc, critical micellar concentration; DCCD, dicyclohexylcarbodiimide; NBD-C1, 7-chloro-4nitro-2,1,3-benzoxadiazole; FITC, fluorescein 5'-isothiocyanate; PMS, jV-methylphenazonium methosulfate; ANS, 8-anilino-1 -naphthalenesulfonate; DTT, dithiothreitol; CHAPS, Deters et al, 1975), heat (Farron & Racker, 1970), or DTT (McCarty & Racker, 1968). However, unlike the thylakoid-bound CFb the purified CF, catalyzes ATP hydrolysis in the presence of Ca2+ rather than Mg2+ ions.…”

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Activation of magnesium ion specific adenosine triphosphatase in chloroplast coupling factor 1 by octyl glucoside

Pick¹,

Bassilian²

1982

Biochemistry

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“…The slow rate of association of ADP and 1 ,A6-ethenoadenosine diphosphate at these sites rules out the possibility that they are catalytic sites for ATPase activity on the solubilized en-l_he coupling factor from spinach chloroplasts (CF¡)1 is believed to be directly involved in photophosphorylation. The solubilized purified enzyme has no ATPase activity unless activated by trypsin (Vambutas and Racker, 1965), heat (Farron and Racker, 1970), or dithiothreitol (McCarty and Racker, 1968). While photophosphorylation and light induced ATPase activities in chloroplasts are dependent on Mg2+ (Petrack et al, 1961(Petrack et al, , 1965McCarty and Racker, 1966), the activated CF] has a Ca2+ dependent ATPase, although a Mg2+ dependent ATPase may be induced by carboxylic acids (Nelson et al, 1972).…”

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Characterization of nucleotide binding sites on chloroplast coupling factor 1

Cantley¹,

Hammes²

1975

Biochemistry

129

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A study of the equilibrium binding of ADP, 1,N6-ethenoadenosine diphosphate, adenylyl imidodiphosphate, and 1,N6-ethenoadenylyl imidodiphosphate to solubilized spinach chloroplast coupling factor 1 (CF1) has been carried out. All four nucleotides were found to bind to two apparently identical "tight" sites, with characteristic dissociation contants generally less than 10 muM. The binding to these "tight" sites is similar in the presence of Mg2+ and Ca2+, is stronger in 0.1 M NaC1 than in 20 mM Tris-C1, and is only slightly altered by heat activation. The slow rate of association of ADP and 1,N6-ethenoadenosine diphosphate at these sites rules out the possibility that they are catalytic sites for ATPase activity on the solubilized enzyme. A third tight site for adenylyl imidodiphosphate was found on the heat-activated enzyme. The dissociation constant for this interaction (7.6 muM) is similar to the adenylyl imidodiphosphate competitive inhibition constant for ATPase activity (4 muM). ADP, which inhibits ATPase activity but is not a strong competitive inhibitor, binds only weakly at a third site (dissociation constant greater than 70 muM). One mole of 7-chloro-4-nitrobenzo-2-oxa-1,3-diazole reacted per mole of CF1 prevents ADP and adenylyl imidodiphosphate binding at the "catalytic" site and abolishes the ATPase activity. A model is proposed in which the "tight" nucleotide binding sites act as allosteric conformational switches for the ATPase activity of solubilizedCF1.

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Partial Resolution of the Enzymes Catalyzing Photophosphorylation

Cited by 355 publications

References 21 publications

Isolation, purification, and characterization of coupling factor 1 from Chlamydomonas reinhardi

Isolation, purification, and characterization of coupling factor 1 from Chlamydomonas reinhardi

Activation of magnesium ion specific adenosine triphosphatase in chloroplast coupling factor 1 by octyl glucoside

Characterization of nucleotide binding sites on chloroplast coupling factor 1

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