AMINO ACID DISTRIBUTION AND INCORPORATION INTO PROTEINS IN ISOLATED, ELECTRICALLY‐STIMULATED CEREBRAL TISSUES

Journal of Neurochemistry - Tập 18 Số 1 - Trang 41-58 - 1971
Daniel A. Jones1, H. McIlwain1
1Department of Biochemistry, Institute of Psychiatry (British Postgraduate Medical Federation, University of London) De Crespigny Park, London. S.E.5.

Tóm tắt

Abstract—The uptake of radioactive amino acid by incubated cerebral cortex slices is found to be a first order process. Incorporation of the radioactive amino acid into tissue protein is from a precursor pool that has first equilibrated with the intracellular endogenous free amino acids. Ways of calculating the amino acid incorporation in molar quantities from the observed incorporation of radioactivity are discussed, and it is concluded that the specific radioactivity of the intracellular acid‐soluble fraction is the best basis for such estimates. The in vitro incorporation of leucine into tissue protein is estimated to be approximately 1±2 mμnol/mg protein/h, and of valine 0±4 mμmol/mg protein/h.Addition of free amino acids to the media had little or no effect on the calculated rates of incorporation. On incubation for 1 h the total free valine in tissue and medium increased by 0±43 μmol/g and leucine increased by 0±55 μmol/g. Estimates of amino acid incorporation based on the specific radioactivity of the media amino acids can give misleading results if this considerable release of amino acids into the medium is not taken into account. Electrical stimulation of neocortical slices with a variety of types of pulses was either without effect or decreased incorporation into portein. The decrease could not be directly correlated with changes in tissue K+ nor with the utilization of ATP. Mild, local stimulation of the lateral olfactory tract of piriform cortex slices was without effect on tissue phosphocreatine, K+ or amino acid incorporation.

Từ khóa


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Thông tin xuất bản

Journal of Neurochemistry

Tập 18 Số 1

41-58

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