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Physiochemical properties of rat liver mitochondrial ribosomes

Patel, Vinood B. and Cunningham, Carol C. and Hantgan, Roy (2001) Physiochemical properties of rat liver mitochondrial ribosomes. Journal of Biological Chemistry, 276 (9). pp. 6739-6746. ISSN 0021-9258

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Official URL: http://www.jbc.org/cgi/content/full/276/9/6739

Abstract

In the present study, the physiochemical properties of rat liver mitochondrial ribosomes were examined and compared with Escherichia coli ribosomes. The sedimentation and translational diffusion coefficients as well as the molecular weight and buoyant density of rat mitochondrial ribosomes were determined. Sedimentation coefficients were established using the time-derivative algorithm (Philo, J. S. (2000) Anal. Biochem. 279, 151-163). The sedimentation coefficients of the intact monosome, large subunit, and small subunit were 55, 39, and 28 S, respectively. Mitochondrial ribosomes had a particle composition of 75% protein and 25% RNA. The partial specific volume was 0.688 ml/g, as determined from the protein and RNA composition. The buoyant density of formaldehyde-fixed ribosomes in cesium chloride was 1.41 g/cm3. The molecular masses of mitochondrial and E. coli ribosomes determined by static lightscattering experiments were 3.57 +/- 0.14 MDa and 2.49 +/- 0.06 MDa, respectively. The diffusion coefficient obtained from dynamic light-scattering measurements was 1.10 +/- 0.01 x 10 -7 cm2 s-1 for mitochondrial ribosomes and 1.72 +/- 0.03 x 10 -7 cm2 s-1 for the 70 S E. coli monosome. The hydration factor determined from these hydrodynamic parameters were 4.6 g of water/g of ribosome and 1.3 g/g for mitochondrial and E. coli ribosomes, respectively. A calculated hydration factor of 3.3 g/g for mitochondrial ribosomes was also obtained utilizing a calculated molecular mass and the Svedberg equation. These measurements of solvation suggest that ribosomes are highly hydrated structures. They are also in agreement with current models depicting ribosomes as porous structures containing numerous gaps and tunnels.

Item Type:Article
Additional Information:Online ISSN 1083-351X
Research Community:University of Westminster > Life Sciences, School of
ID Code:414
Deposited On:17 Aug 2005
Last Modified:11 Aug 2010 15:29

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