PubMed Health⌕ Search

Biomedical subjects

Y Georgalis

Publications and source records attributed to Y Georgalis.

25 records · Page 2Linked to original sources
PubMed1989

Comparative studies of ribulose-1,5-biphosphate carboxylase/oxygenase from Alcaligenes eutrophus H16 cells, in the active and CABP-inhibited forms.

RuBisCO (D-ribulose-1,5-biphosphate carboxylase/oxygenase; EC 4.1.1.39) has been isolated from the autotrophic hydrogen-oxidizing bacterium Alcaligenes eutrophus H16. Combining photon correlation and sedimentation analysis transport parameters of the enzyme were investigated in the active, (E.CO2.Mg2+) as a ternary complex, and inactive state, (E.CO2.Mg2+.CABP) as a quaternary complex, where RuBisCO is complexed with the transition state analogue CABP (2-C-carboxy-D-arabinitol-1,5-biphosphate). Within experimental error, no difference has been detected between the diffusion and sedimentation coefficients (D020,w = 2.72(+/- 0.07) x 10(-7) cm2 s-1, s020,w = 17.8(+/- 0.5)S) of active and CABP-complexed enzyme thus leading to the conclusion that the molecule, at least in solution, does not assume a different conformation when complexed with CABP.

Alcaligenes↗
PubMed1989

The tetrameric form of ribosomal protein L7/L12 from Escherichia coli.

A tetrameric form of the ribosomal protein L7/L12 has been prepared and its structure studied by using hydrodynamic methods, photon correlation spectroscopy, and small angle x-ray scattering. The tetrameric nature of the protein preparation is confirmed by three independent determinations of its molecular weight, with analysis of accurate sedimentation equilibrium data giving the most reliable estimate. The species has a Stokes radius of 4.0 +/- 0.1 nm and an absolute frictional ratio of 1.7. Taken together, the hydrodynamic measurements suggest the possibility of a flat structure, and this is consistent with the x-ray scattering results. The molecule has a radius of gyration of 3.6 +/- 0.05 nm and a maximum dimension of 11-12 nm. A geometric model consisting of four elongated monomers, arranged in a plane, is proposed.

Bacterial Proteins↗
PubMed1981

Physical studies on the ribosomal protein S2 from the Escherichia coli 30S.

The protein S2 has been isolated from the 30S subunit of Escherichia coli A19 ribosomes [Littlechild, J., & Malcolm, A.L. (1978) Biochemistry 17, 3363-3369]. This salt-extracted protein is soluble and does not aggregate at salt concentrations of 0.3-0.4 M as used under reconstitution conditions. This differs from the S2 protein extracted by the acetic acid and urea method. The molecular weight from sedimentation equilibrium was found to be 29 200, and the protein was found to have a S0(20,w) value of 2.36S. The apparent specific volume at 20 degrees C was 0.726 mL.g(-1), and the D0(20,2) was 7.37 x 10(-7) cm(2)s(-1). The value for intrinsic viscosity was found to be 6.42 mL.g(-1). An axial ratio of (5-6):1 for a prolate ellipsoid of revolution was estimated by using these parameters. The circular dichroism and proton magnetic resonance studies show that protein S2 has both substantial amounts of alpha helix and beta-pleated sheet in solution and appears as a "folded" protein and not a random coil structure.

Circular Dichroism↗
PubMed1981

Identity of the B56.5 protein, the A-protein, and the groE gene product of Escherichia coli.

Protein B56.5 is a major Escherichia coli protein, originally identified on two-dimensional gels as an abundant cellular protein with unique regulation. The groE gene product is a bacterial protein essential for the assembly of many diverse bacteriophages. The ribosomal A-protein is a large, acidic protein of unknown function associated with isolated, washed ribosomes. On the basis of comigration in two-dimensional gels, oligopeptide map patterns, amino acid composition, immunological specificity, physical properties, and genetic analysis, protein B56.5 has now been shown to be the groE gene product and to be identical with the A-protein.

Bacterial Proteins↗
PubMed1979

Shape of proteins S3 and S17 from the small subunit of Escherichia coli ribosome.

The shapes of proteins S3 and S17 purified from the 30 S subunit of Escherichia coli A19 were studied by hydrodynamic methods. The proteins have s020,w values of 2.1 +/- 0.1 S and 1.2 +/- 0.1 S and D020,w values of 7.4 +/- 0.5 . 10(-7) cm2/s and 11.4 +/- 0.6 . 10(-7) cm2/s. The respective molecular weights determined by sedimentation equilibrium are 25 800 +/- 500 and 9900 +/- 300. The intrinsic viscosity values for the two proteins are 5.8 +/- 0.3 ml/g and 4.2 +/- 0.2 ml/g. From these hydrodynamic parameters a slightly elongated shape for S3 and a globular shape for S17 have been concluded.

Bacterial Proteins↗