Effect of Protein Depletion on Amino-acid Activating Enzymes of Rat Liver

Mariani, A.; Spadoni, M. A.; Tomassi, G.

doi:10.1038/199378a0

Cited by 40 publications

(14 citation statements)

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“…Schimke (1962) has shown that on a protein-free diet the activity of most of the urea-cycle enzymes is reduced. Spadoni and co-workers (Mariani, Spadoni & Tomassi, 1963 ;Gaetani, Paolucci, Spadoni & Tomassi, 1964) found that a low-protein diet causes an increase in the activity of amino acid-activating enzymes in the liver. T h e effect of these two changes must be that a free amino acid molecule in the liver cell, whether it has come from the food, from the katabolism of extrahepatic protein, or from that of liver protein, will have a smaller chance of being degraded to urea, and a greater chance of being re-incorporated into protein.…”

Section: Vol 20mentioning

confidence: 99%

Adaptation of the rat to a low-protein diet: the effect of a reduced protein intake on the pattern of incorporation of L-[¹⁴C]lysine

Waterlow

Stephen

1966

Br J Nutr

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I. Rats were chronically depleted of protein by being kept on a 6 % casein diet for 5-8 weeks. Control rats were fed on a normal diet. Both groups were injected intraperitoneally with ~-[U-'~C]lysine. Some rats from each group were then put on a protein-free diet to produce acute depletion. The animals were killed 3 days after the injection. 2. The organs and tissues were analysed for total nitrogen and radioactivity. Free lysine, total amino N and specific activity of free lysine were measured in muscle, liver and serum. The total muscle mass of the animals was determined. Samples of muscle and skin were fractionated and the sp. ac. of the fractions was measured. 3. The main loss of N in acute depletion was found in the viscera and carcass residue; the percentage of total body N contributed by muscle was increased in protein-depleted rats. 4. The depleted rats retained relatively more radioactivity in the internal organs and less in the carcass than normal rats. 5 . The ratio of the sp. ac. in protein-bound lysine to the sp. ac. of free lysine showed that protein synthesis was reduced in the muscle of the protein-depleted rats, although there was no decrease in the amount or sp. ac. of free lysine even in severe depletion. 6. Sarcoplasmic and fibrillar proteins of muscle were equally affected by protein depletion, but there was some indication of a preferential decrease in protein synthesis in one of the skin fractions. 7. The results for muscle protein are compared with those given in the literature for liver proteins. It is suggested that the rat adapts to a low-protein intake by an alteration in the pattern of protein synthesis, When a rat is given a single dose of a labelled amino acid the distribution of the label between the different organs and tissues of the body is dependent upon the dietary state of the animal. For example, 3 days after the injection of ~~-[~~S ] m e t h i o n i n e , in normal rats 75% of the radioactivity recovered was found in the carcass (muscle, skeleton and skin), 25% in the internal organs. I n rats on a low-protein diet these proportions were different; nearly 50% of the radioactivity recovered was in the viscera (Waterlow, 1959 In the experiments to be presented we have been concerned mainly with muscle, which, as the largest protein mass in the body, is of especial nutritional interest. We have tried to determine whether the reduced uptake of labelled amino acid by muscle in protein-depleted rats could be accounted for either by changes in the specific activity of the free amino acid, or by changes in the relative amounts and activities of the two main muscle fractions, sarcoplasmic and fibrillar proteins. Some observations have also been made on skin, which in the rat contains 25-30% of the total body nitrogen.In almost all these experiments the amino acid used was lysine. Most of the measurements were made 3 days after injection of the labelled amino acid, because it was found in previous work that this was the time interval at which differences in incorporation were most ...

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Section: Vol 20mentioning

confidence: 99%

Adaptation of the rat to a low-protein diet: the effect of a reduced protein intake on the pattern of incorporation of L-[¹⁴C]lysine

Waterlow

Stephen

1966

Br J Nutr

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“…It appears that rats protein-deprived for only' one day cannot develop a sufficient "amino acid sparing metabolic state," considering that adaptations, to the protein deficient diets usually take more than several days to reach a maximum leveJ. 16,23) The lower column of Fig. 1.…”

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Effect of Severity of Protein Depletion on the Subsequent Hepatic “Catch-up” Growth in Young Adult Rats

Miyazawa

Kametaka

1984

Agricultural and Biological Chemistry

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“…This hypothesis has been supported by Mariani et al,14) who observed a stimulation of amino acid activating systems in the liver homogenate from protein-depleted rats. On the other hand, upon feeding of an unbalanced protein diet such that devoided a single essential amino acid, the effects on the protein metabolism are expected to be somewhat different from protein depletion, in the respect that all but one of excess amino acids are actually ingested and penetrated into tissues.…”

Section: Discussionmentioning

confidence: 57%

Effect of Essential Amino Acid-deficiency on Protein Nutrition

Nishimura

Kandatsu²

1970

Agricultural and Biological Chemistry

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Effect of Protein Depletion on Amino-acid Activating Enzymes of Rat Liver

Cited by 40 publications

References 10 publications

Adaptation of the rat to a low-protein diet: the effect of a reduced protein intake on the pattern of incorporation of L-[¹⁴C]lysine

Adaptation of the rat to a low-protein diet: the effect of a reduced protein intake on the pattern of incorporation of L-[¹⁴C]lysine

Effect of Severity of Protein Depletion on the Subsequent Hepatic “Catch-up” Growth in Young Adult Rats

Effect of Essential Amino Acid-deficiency on Protein Nutrition

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Effect of Protein Depletion on Amino-acid Activating Enzymes of Rat Liver

Cited by 40 publications

References 10 publications

Adaptation of the rat to a low-protein diet: the effect of a reduced protein intake on the pattern of incorporation of L-[14C]lysine

Adaptation of the rat to a low-protein diet: the effect of a reduced protein intake on the pattern of incorporation of L-[14C]lysine

Effect of Severity of Protein Depletion on the Subsequent Hepatic “Catch-up” Growth in Young Adult Rats

Effect of Essential Amino Acid-deficiency on Protein Nutrition

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Adaptation of the rat to a low-protein diet: the effect of a reduced protein intake on the pattern of incorporation of L-[¹⁴C]lysine

Adaptation of the rat to a low-protein diet: the effect of a reduced protein intake on the pattern of incorporation of L-[¹⁴C]lysine