Über Actin-Nucleotide und die Funktion und Bindung der Nucleotidphosphate im G- und F-Actin

Grubhofer, N.; Weber, Hans Hermann

doi:10.1515/znb-1961-0707

Cited by 53 publications

(14 citation statements)

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“…Steps I and I1 are in agreement with Grubhofer and Weber (1961). G-actin ATP e ATP + G-actin I + G'-actin G"-actin I1…”

Section: Biochemistrysupporting

confidence: 77%

“…Native cold-extracted G-actin-ATP, ; same, after irreversible dissociation from the bound nucleotide with EDTA and Dowex 1 treatment, x; same, in 8 M urea, A properties of G-actin-ATP. Addition of 10 p 3 M EDTA partially removes the bound nucleotide within 30 minutes (Biriny etnl., 1961b;Grubhofer and Weber, 1961;Maruyama and Martonosi, 1961;Strohman and Samorodin, 19621 and the rotatory properties begin to change. After 24 hours the bound nucleotide removal by EDTA is complete and the rotatory values are lowered, but still not to the level of a completely random coil structure.…”

Section: Optical Rotatory Properties Of Actin Extracted Atmentioning

confidence: 99%

“…The removal of the bound nucleotide from actin is an irreversible proceas under most conditions, although under certain conditions a time-dependent partial reversibility has been observed ( B k b y et al., 1961a,b;Grubhofer and Weber, 1961;Maruyama and Gergely, 1961;Strohman and Samorodin, 1962). It has been suggested that the dissociation of G-actin and ATP is accompanied by a conformational change of the protein (Asakura, 1961;Strohman and Samorodin, 1962).…”

mentioning

confidence: 99%

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Optical Rotatory Dispersion of G-Actin

Nagy¹,

Jencks²

1962

Biochemistry

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“…Steps I and I1 are in agreement with Grubhofer and Weber (1961). G-actin ATP e ATP + G-actin I + G'-actin G"-actin I1…”

Section: Biochemistrysupporting

confidence: 77%

Section: Optical Rotatory Properties Of Actin Extracted Atmentioning

confidence: 99%

mentioning

confidence: 99%

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Optical Rotatory Dispersion of G-Actin

Nagy¹,

Jencks²

1962

Biochemistry

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“…Early measurements of the cation content in crude actin preparations found varying amounts of Ca 2+ and Mg 2+ (Feuer et al, 1948;Hasselbach, 1957;Chrambach et al, 1961), with the notion that monomeric G-actin tightly binds approximately one mole Ca 2+ per mole protein becoming generally accepted (Grubhofer & Weber, 1961;Maruyama & Gergely, 1961;Tonomura & Yoshimura, 1961;Strohman & Samorodin, 1962;Martonosi et al, 1964). At about the same time, it became appreciated that the G-actin-bound metal ion was freely exchangeable with exogenous divalent cations.…”

Section: Identity Of Actin-bound Cationmentioning

confidence: 99%

Tightly-bound divalent cation of actin

Estes

Selden

Kinosian

et al. 1992

J Muscle Res Cell Motil

134

135

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Actin is known to undergo reversible monomer-polymer transitions that coincide with various cell activities such as cell shape changes, locomotion, endocytosis and exocytosis. This dynamic state of actin filament self-assembly and disassembly is thought to be regulated by the properties of the monomeric actin molecule and in vivo by the influence of actin-associated proteins. Of major importance to the properties of the monomeric actin molecule are the presence of one tightly-bound ATP and one tightly-bound divalent cation per molecule. In vivo the divalent cation is thought to be Mg2+ (Mg-actin) but in vitro standard purification procedures result in the preparation of Ca-actin. The affinity of actin for a divalent cation at the tight binding site is in the nanomolar range, much higher than earlier thought. The binding kinetics of Mg2+ and Ca2+ at the high affinity site on actin are considered in terms of a simple competitive binding mechanism. This model adequately describes the published observations regarding divalent cation exchange on actin. The effects of the tightly-bound cation, Mg2+ or Ca2+, on nucleotide binding and exchange on actin, actin ATP hydrolysis activity and nucleation and polymerization of actin are discussed. From the characteristics that are reviewed, it is apparent that the nature of the bound divalent cation has a significant effect on the properties of actin.

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“…Calculation of Equilibrium Constant. The following equation appears to account for the inactivation process (Grubhofer and Weber, 1961…”

Section: Methodsmentioning

confidence: 99%

Binding of adenosine diphosphate to G-actin

West¹

1970

Biochemistry

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The binding of adenosine diphosphate (ADP) by G-actin was studied under various conditions. Binding constants were determined by measuring either the rates of denaturation of G-actin solutions in the presence of varying nucleotide concentrations, or the concentration of free nucleotide in G-actin solutions at equilibrium. The binding constant of G-actin for ADP at 0" was 2-5 X lo6 M -~; a t 25" it was 4 X l o 4 M -~, whereas at 0" ATP bound to G-actin with an affinity constant of 2.4 X IO7 M -~, Changing the I n view of the possible role of actin-bound nucleotide in energy-transfer processes leading to muscle contraction, studies of the properties of actin-bound nucleotide are important. Several recent publications have presented conflicting evidence on the extent to which ADP-G-actin dissociates in solution to form ADP and native G-actin. Higashi and Oosawa (1965) derived a binding constant of G-actin for ADP of 1.3 X lo4 M -~ from studies of changes in absorbance at 230 m p after addition of ADP to ADP-G-actin solutions. Thus, according to these data, at 1.5 mg/ml of ADP-G-actin in the absence of added ADP only 20% of the nucleotide was actually bound to the protein. Seidel et al. (1967) determined the amount of native actin containing no bound nucleotide and estimated that the binding constant of G-actin for ADP a t 4" was 4 X IO6 M -~. I n contrast, Hayashi and Rosenbluth (1964) inferred that less than 5 % of the total nucleotide present was free after studies of removal of free nucleotide by Dowex 1 from 1 mgjml of ADP-G-actin solutions at 0". West et al. (1967a) studied the kinetics of ADP hydrolysis by apyrase and found that only 7 of the nucleotide was dissociated in 1.5 mg/ml of ADP-G-actin solutions at 0". If the free nucleotide in these studies was equivalent to that found at equilibrium these results imply a binding constant greater than 7 X 106 M -~, a value 500-fold greater than that calculated by Higashi and Oosawa (1965) and 20-fold greater than that determined by Seidel et al. BBCB and a Veterans Administration Hospital Clinical Investigatorship. actin-bound cation from magnesium to calcium did not appear to alter ADP binding. Free magnesium at a concentration of 0.2 mM reduced the rate of G-actin denaturation by onethird but there was no change in the affinity of G-actin for ADP.It was concluded that the mechanism by which free magnesium stabilizes G-actin depends on a prolonged lifetime of nucleotide-free G-actin molecules without change in the properties of G-actin containing bound nucleotide. excess of magnesium at 0" retarded thermal denaturation of ADP-G-actin. It seemed possible that such a stabilizing effect of free MgCI2 could have been mediated by an increased affinity of G-actin for ADP.Our results show tighter ADP binding to G-actin at 0" than found in previous studies. A marked temperature dependence for ADP binding to G-actin was found. Nucleotide binding was not altered if calcium was substituted for actin-bound magnesium, nor did addition of free magnesium alter nucleotide b...

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Über Actin-Nucleotide und die Funktion und Bindung der Nucleotidphosphate im G- und F-Actin

Cited by 53 publications

References 0 publications

Optical Rotatory Dispersion of G-Actin

Optical Rotatory Dispersion of G-Actin

Tightly-bound divalent cation of actin

Binding of adenosine diphosphate to G-actin

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