1. Rats were injected with [U-14C]glucose and after various intervals extracts of whole brain proteins (and in some cases proteins from liver, blood and heart) were prepared by high-speed centrifugation of homogenates in 0.9% sodium chloride or 0.5% sodium deoxycholate. 2. The extracts were subjected to gel filtration on columns of Sephadex G-200 equilibrated with 0.9% sodium chloride or 0.5% sodium deoxycholate. 3. Extracts prepared with both solvents displayed on gel filtration a continuous range of proteins of approximate molecular weights ranging from less than 2×104 to more than 8×105. 4. The relative amount of the large proteins (mol.wt.>8×105) was conspicuously higher in brain and liver than in blood. 5. At 15min after the injection of [U-14C]glucose the smaller protein molecules (mol.wt.<2×104) were significantly radioactive, whereas no 14C could be detected in the larger (mol.wt.>2×104) protein molecules. The labelling of all protein samples was similar within 4h after injection of [U-14C]glucose. Fractionation of brain proteins into distinctly different groups by the methods used in the present work yielded protein samples with a specific radioactivity comparable with that of total brain protein. 6. No evidence could be obtained by the methods used in the present and previous work to indicate the presence of a significant amount of ‘metabolically inert protein’ in the brain. 7. It is concluded that: (a) most or all of the brain proteins are in a dynamic state of equilibrium between continuous catabolism and anabolism; (b) the continuous conversion of glucose into protein is an important part of the maintenance of this equilibrium and of the homoeostasis of brain proteins in vivo.
Skip Nav Destination
Research Article| February 01 1970
Molecular weights and metabolism of rat brain proteins
R. Vrba ;
Biochem J (1970) 116 (4): 745–753.
- Views Icon Views
- Share Icon Share
R. Vrba, Wendy Cannon; Molecular weights and metabolism of rat brain proteins. Biochem J 1 February 1970; 116 (4): 745–753. doi: https://doi.org/10.1042/bj1160745
Download citation file:
Don't already have an account? Register
Get Access To This Article
Buy This Article