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H TARVER

Publications and source records attributed to H TARVER.

At least 19 recordsLinked to original sources
PubMed1957

Studies on protein synthesis in vitro. VI. Incorporation and release of amino acids in particulate preparations from livers of rats.

The release of radioactive amino acid from the particulate fractions separated from the prelabelled livers of rats by centrifugation has been studied under various conditions. Although pure fractions may not have been obtained, great differences in behavior were observed. In the mitochondria and nuclei dinitrophenol (10(-4)M) causes an inhibition of release, but in microsomes the opposite effect is observed. When the incubation medium is fortified with ATP and phosphocreatine, release is inhibited. In microsomes and nuclei the inhibition proceeds to the extent that the incorporation of preformed radioactive amino acid occurs. Protein is synthesized at a rapid rate. In incubations longer than 1 hour there is always a release of radioactive amino acid. It is concluded from these results that the interpretation of release data from slices or systems such as those studied is impossible without further information concerning some of the unknown variables. The most important unknown is the specific activity of the "free" amino acid in the particulates and the effect of carrier amino acid in the medium of this specific activity.

Amino Acids↗
PubMed1956

Protein synthesis in the perfused rat liver.

1. When the rat livers are perfused under the conditions of these experiments with rat blood diluted with saline, the livers remain capable of removing colloidal chromic phosphate normally for 4 hours or more; that is, the reticuloendothelial system continues to function normally. 2. Good rates of bile flow continue, generally for 4 hours. 3. The livers incorporate radioactivity from the amino acids methionine, lysine, and histidine at rapid rates for 1 or 2 hours. Thereafter the rates fall. 4. The specific activity of the free lysine and histidine in the perfusate falls rapidly during the experiments (to 25 or 35 per cent of its original value at 10 minutes). 5. The fall in rate of incorporation of radioactivity is attributable to the fall in amino acid specific activity. 6. Addition of a complete amino acid mixture to the perfusate does not appear to have any stimulatory effect on incorporation of radioactivity from labelled amino acids. 7. With lysine, on the assumption that incorporation is due to new protein formation, there is a rate of synthesis equivalent to 230 mg. of plasma protein per 100 gm. of rat per day. This result is in agreement with turnover data obtained from rats in vivo. 8. The results emphasize once again the importance of precursor specific activity in the interpretation of metabolic experiments with labelled amino acids.

Amino Acids↗