Structure of human serum lipoproteins in solution

Luzzati, Vittorio; Tardieu, A.; Mateu, L.; Stuhrmann, H. B.

doi:10.1016/0022-2836(76)90367-3

Cited by 94 publications

(52 citation statements)

References 12 publications

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“…Information concerning the internal structure of the M subunit and of its complex with ATP can be achieved by changing the electron density of the solvent with sucrose and observing changes in R,. [27], regardless of the sucrose concentration. The slope of the straight line yields the radius of gyration of the excluded volume (R,,,) that was found to be 2.67 nm for the M subunit alone and 2.45 nm for the M subunit in the presence of 5 mM ATP.…”

Section: Radius Of Cvrationmentioning

confidence: 88%

“…The molecular weight of a can be obtained from smallangle X-ray scattering experiments at zero angle intensity, also, since the scattered intensity, i,,(0, go), is compared with the energy of the incident beam, and the experimental curves are normalized and put on an absolute scale [8,27]. In the case of a two-component system, which is met when the buffer does not contain sucrose, the mass of the particle, ni, expressed in number of electrons in the particle, is given by (2) with o0 the electron density of the solvent in e/nm3, cE the electron concentration, expressed as the ratio of the number of electrons of the protein to that of the solution, and t b the partial specific volume per electron.…”

Section: Molecular Weightmentioning

confidence: 99%

“…From the slope of the straight line F 2 was determined to be 0.737(1) ml g-' at I = 0.15 M, pH 8.0, for a. In the system studied it is [27]. I = 0.15 M presumed that each a particle in solution is accompanied by a fixed amount of water, impenetrable to sucrose [20].…”

Section: Molecular Weightmentioning

confidence: 99%

“…I = 0.15 M presumed that each a particle in solution is accompanied by a fixed amount of water, impenetrable to sucrose [20]. Assuming that the invariant volume hypothesis is valid [27,28] and considering a and a-ATP with only water associated with it, is a constant whose value specifies the amount of bound water (Table 1). Since sucrose is excluded from the solute, the data are not compatible with any amount of bound sucrose.…”

Section: Molecular Weightmentioning

confidence: 99%

“…The molecular weight of a, applying the determined partial specific volumes, was found to be 57 700 for LY and 57 100 for c(-ATP (Table 1). Correct molecular weights for a and sr-ATP from small-angle X-ray scattering data can be obtained if the partial specific volume and the electron density is the scattering amplitude put on an absolute scale [27],…”

Section: Molecular Weightmentioning

confidence: 99%

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Size and Shape of the α Subunit of the (Ca,Mg)‐dependent Adenosinetriphosphatase from Escherichia coli in Solution in the Presence and Absence of ATP

Paradies

1981

European Journal of Biochemistry

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The a subunit of the (Ca, Mg)-dependent ATPase from Esclzerichin coli was studied in solution by means of X-ray scattering experiments at variable contrast and in the presence of ATP. The experiments were carried out on an absolute scale in the range of (45.0 nm-') < h < (1.5 nm-') at pH 8.0. The experiments show that this system and the complex of the a subunit with ATP can be considered to be ideal and monodisperse so that the following parameters for the M subunit and its complex with ATP were determined: the radius of gyration, the volume, the degree of hydration, the maximum particle diameter, and the molecular weight. The molecular weight of the M subunit was determined as 58500 3000 by means of light scattering measurements, and 57700 f 2500 by the small-angle X-ray scattering experiments. The radius of gyration of the a subunit at pH 8.0 was determined to 2.64 & 0.02 nm, the maximum chord in solution to 10.0 * 0.5 nm, the volume to 102.4 * 2.5 nm3, and the degree of hydration to 0.34 f 0.02 ml . gi'. Binding of ATP to the M subunit causes structural changes. These changes are reflected in the radius of gyration, R , = 2.45 f 0.015 nm, in the volume, 117.6 1.5 nm3, and in the maximum chord length in solution, 7.8 & 0.5 nm. These changes imply a decrcase of the axial ratio from 2.4 to 1.4, i.e. ATP-binding induced an increase in isometry of the a subunit.Proton-translocating ATPase (H+-ATPase) has been isolated from a variety of membranes in which oxidative phosphorylation or photophosphorylation takes place [l, 21. The H+-ATPase is composed of two multisubunit parts: a watersoluble portion (Fl), composed of five different subunits, appears to be peripheral to the membrane, catalyzing a dicyclohexylcarbodiimide-insensitive hydrolysis of ATP, and a hydrophobic portion (Fo) which is an integral part of the membrane and mediates proton translocation as well as causing dicyclohexylcarbodiimide sensitivity [ 1,2]. This part of the complex (Fo) has a molecular weight of the order of 90000 -1 15 000 [3 -51, whereas the molecular weight of the peripheral part of the H+-ATPase (F1) is in the range of Reconstitution experiments for F1 from Escherichiu coli have been performed revealing that M , p and y subunits are required for ATPase activity [ll]. Moreover, ATPase activities were reconstituted from complexes containing different subunit proportions of E. coli ATPase [12] as well as from purified individual subunits of the ATPase of the thermophilic bacterium PS3 [13,14]. The isolated subunits of FI [11, 121 probably exist in conformations which are similar to their native forms, inferred from recombination experiments to produce an FI complex which is functional in oxidative phosphorylation. The availability of such subunits provides the opportunity to study their physical properties, ligand binding and interaction with other subunits.One important finding obtained through the study of isolated subunits is that the CI subunit of F1 from E. coli binds ATP or ADP with Kd values of 0.1 pM and 0.9 pM respectively [I 5...

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Section: Radius Of Cvrationmentioning

confidence: 88%

Section: Molecular Weightmentioning

confidence: 99%

Section: Molecular Weightmentioning

confidence: 99%

Section: Molecular Weightmentioning

confidence: 99%

Section: Molecular Weightmentioning

confidence: 99%

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