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IN VITRO PROTEIN SYNTHESIS ON FREE POLYRIBOSOMES ISOLATED FROM THE DEVELOPING MOUSE BRAIN
Author(s) -
Campagi A. T.,
Harris J. R.
Publication year - 1977
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.1977.tb10430.x
Subject(s) - polysome , in vitro , biochemistry , chemistry , protein biosynthesis , biology , ribosome , rna , gene
— Free polyribosomes were isolated at three ages (newborn, 2 weeks and 8 weeks) from the developing mouse brain. All three preparations were found to be highly polyribosomal in nature and were essentially identical with respect to their chemical composition and sedimentation properties. An estimate of the sedimentation coefficients of the first seven members of these polysome preparations yielded S ° 20,w values of 76, 114, 146, 174, 196, 217 and 236. All three preparations were found to be very active when employed in in vitro protein synthesizing systems. An age‐dependent response to the concentration of K + was observed in the activities of the in vitro protein synthesizing systems. Optical K + concentrations for the 0, 2 and 8 week old systems were 30, 50 and 65 mm, respectively. No such age dependence was observed when NH + 4 was used as the sole monovalent cation, with all systems exhibiting maximal activity at 50mm‐NH + 4 . The highest in uitro activities were consistently observed (at all three ages) when NNH + 4 was employed as the sole monovalent cation. Under optimal conditions, the newborn in vitro protein synthesizing system was observed to be approx 40% as active as either the 2 week or the 8 week systems which were equivalent in activity. The reduced activity of the newborn system appeared to be a function of both the polyribosomal and pH 5 enzyme preparations.