1. Rats were injected serially with [(14)C]glucose to obtain a constant specific radioactivity of brain amino acids. Measurements with this system for periods of up to 8h gave an apparent mean half-life for protein in whole brain of 85h (indicating the presence of a protein fraction with much more rapid turnover than this). 2. The half-lives of proteins in the granule-cell, molecular and white-matter layers of cerebellum were also determined. These had values of 33, 59 and 136h respectively. In addition, the incorporation into protein in six layers of the cerebral cortex, subjacent white matter and five layers of Ammon's horn was studied. All cell-body layers incorporated amino acids at about the same rate irrespective of location, and these rates were considerably higher than those for incorporation into proteins in areas rich in dendrites or fibre tracts. 3. A new method for measuring small amounts of glutamate with a cyclic enzyme system is presented.

Amino Acids↗

PubMed1972

Dopamine -hydroxylase of bovine adrenal medullae. A rapid purification procedure.

1. A rapid purification procedure for dopamine beta-hydroxylase from bovine adrenal-medulla chromaffin granules is presented. The homogeneity of the purified enzyme was demonstrated by means of three independent criteria. The specific activity of the enzyme compares favourably with that obtained by more involved procedures. 2. The stability of the enzyme was investigated and storage in polypropylene tubes was found preferable to storage in glass. 3. The soluble and particulate forms of dopamine beta-hydroxylase appear to be identical, since membrane-bound and membrane-enclosed forms of the enzyme exhibit similar properties as regards size, charge and amino acid composition. 4. Ca(2+) was found to stimulate the release of dopamine beta-hydroxylase from bovine chromaffin granules in vitro. 5. An endogenous inhibitor of the enzyme was found in the chromaffin granules. This inhibitor was not inactivated either by heating at 100 degrees C or by pretreatment with p-chloromercuribenzoate or Cu(2+) ions.

Adrenal Medulla↗

PubMed1970

The effect of DFP on axonal transport of protein in chicken sciatic nerve.

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Animals↗

PubMed1970

The effect of colchicine on the transport of axonal protein in the chicken.

1. Small doses (1-10mug) of colchicine injected into the ventral horn of the spinal cord of the chicken caused paralysis in the legs. 2. Colchicine had no effect on the incorporation of leucine into proteins of the spinal cord but markedly decreased the total amount of protein flowing into the axons of the sciatic nerve. 3. This axonal flow of protein proceeded at two rates: a high rate (300mm/day) and a low rate (2mm/day). Although both groups of proteins were affected, the slow transport of protein was more profoundly blocked by colchicine. 4. The results suggest that axonal flow is dependent on the neurotubular system in the axon.

Animals↗

PubMed1970

The binding in vitro of colchicine to axoplasmic proteins from chicken sciatic nerve.

1. Axoplasmic proteins were fractionated by means of Sephadex G-200 chromatography followed by isoelectric focusing. Nine groups of proteins were separated. 2. The binding of colchicine to these groups of proteins was examined and it appeared to associate most strongly with one protein group, of pI value 4.9-5.0, which is the major (14)C-labelled component of slow-transport protein. 3. Other fractions also bind colchicine. It is not clear whether these are separate proteins or subunits of the major colchicine-binding fraction.

Animals↗

PubMed1970