The Influence of Plane of Nutrition and of Environmental Temperature on the Relationship between Basal Metabolism and Endogenous Nitrogen Metabolism Subsequently Determined

Treichler, Ray; Mitchell, H. H.

doi:10.1093/jn/22.4.333

Cited by 26 publications

(6 citation statements)

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“…Examination of the literature suggested that rats receiving low and high levels of protein intake provide the necessary contrast. Several reports indicate that reduction of the intake of a protein-free diet may not alter the nitrogen balance of rats (Mitchell, 1924;Treichler & Mitchell, 1941;Vars & Gurd, 1947), at least until intake represents less than half the voluntary consumption (Swanson, 1951). On the other hand, addition of carbohydrate or fat todiets containing adequate amounts of protein results in an improvement in the nitrogen balance of the rat (Forbes, Bratzler, Thacker & Marcy, 1939;Forbes & Swift, 1944;Lathe & Peters, 1949).…”

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confidence: 99%

The influence of energy intake on protein metabolism

Munro

Naismith

1953

Biochemical Journal

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atom Cr/carboxyl group. With increasing basicity the size of the chromic complex increases, so that the carboxyl groups which can form stable compounds will now be associated with several chromium atoms. The more isolated groups remain ineffective, and we see that the ratio of fixed chromium to total carboxyl approaches unity. The absence of an upward inflexion from the curve for highly acetylated collagen may imply that the largest chromic complexes cannot be firmly held without the help of more than one stabilizing group. When all the amino and nearly all the hydroxyl groups have been acetylated, stabilization of the bound chromium is dependent entirely on the carboxyl and, perhaps, guanidino groups.Normal collagen, on the other hand, contains about 2-8 amino or hydroxyl groups for every free carboxyl, and there is a much higher probability that every chromic complex reacting with carboxyl will also be able to co-ordinate with one or other of the former. More chromium will be fixed even from solutions of low basicity, and at high basicities the rapidly growing polynuclear complexes will come within the range of additional co-ordinating groups and will be firmly held. This double effect of large particle size in the chromic salt coupled with greater availability of amino and hydroxyl groups can be expected to cause the sharp upward sweep of the curves in Fig. 2.The fact that several groups must be acetylated to block the entry of one chromium atom does not, of course, imply that all are attached to that atom. It is purely a probability effect resulting from the fact that all groups can be expected to be equally susceptible to acetylation but that only some of them are placed near carboxyl groups. If it is assumed that the amino and hydroxyl groups of collagen are randomly distributed, that all are equally effective in co-ordinating chromium and that all groups of the same kind are equally easily acetylated, then, at least at moderate basicities, the fixation of chromium should be linearly related to the degree of acetylation, as in Fig. 3. The lower curve of this figure shows that similar considerations apply to reactions with anionic chromium complexes. SUMMARY 1. Acetylation of either free amino or free hydroxyl groups of collagen causes a marked diminution of its ability to take up either cationic or anionic chromium complexes from solution.2. For chromic sulphate solutions, this effect has been studied over a wide range of basicities and for differing degrees of acetylation. It is most pronounced at high basicity and increases almost linearly with the degree of acetylation.3. The experimental results suggest that, while the initial reaction between the chromic complex and collagen occurs at the carboxyl groups of the latter, the co-ordination of amino or hydroxyl radicals is essential to the formation of a stable compound.4. In the basicity range normally employed in industrial chrome tanning, approximately one collagen amino or hydroxyl group in every three appears to be involved in the reaction.

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The influence of energy intake on protein metabolism

Munro

Naismith

1953

Biochemical Journal

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“…Excretion of nitrogenous compounds other than amino acids was also increased in the cold regardless of whether food intake was equalized (Lathe and Peters, 1949;Ingle et al, 1953) or whether the iats were allowed to feed ad libitum (Hannon and Young, 1959;Treichler and Mitchell, 1941;You et al, 1950). Cold-exposed rats excrete more urea, allantoin,creatine, (Young and Cook, 1955;Mefferd et al, 1958;Hale and Mefferd, 1958), creatinine (Treichler and Mitchell, 1941;Selye, 1946; Chinn et al) and uric acid (Chinn et al).…”

Section: Alterations Of Protein Metabolism During Cold Acclimation*mentioning

confidence: 99%

“…Cold-exposed rats excrete more urea, allantoin,creatine, (Young and Cook, 1955;Mefferd et al, 1958;Hale and Mefferd, 1958), creatinine (Treichler and Mitchell, 1941;Selye, 1946; Chinn et al) and uric acid (Chinn et al).…”

Section: Alterations Of Protein Metabolism During Cold Acclimation*mentioning

confidence: 99%

Alterations of Protein Metabolism During Cold Acclimation

Gj¹,

Da²

1963

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“…The endogenous catabolJ:sm.--The relationship between the endog enous catabolism of nitrogen and the basal metabolism revealed by the investigations of Terroine (4) and Smuts (5) may be distorted, in the rat at least, by certain conditions prevailing prior to the measure ment of these two factors (31). A prior high caloric intake raises the basal metabolism without affec ting the output of endogenous nitrogen, while a low prior e:1Vironmental temperature raises the endogenous output of nitrogen without affecting per se the basal metabolism.…”

Section: Gi'neral Phases Of Protein Metabolismmentioning

confidence: 99%

The Metabolism of Proteins and Amino Acids

Mitchell¹

1942

Annu. Rev. Biochem.

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Perhaps the most significant series of investigations on the metab olism of proteins and amino acids, extending into the current year, has been carried out in this country by a group of scientists headed by Rudolf Schoenheimer, whose presence in this country was more a matter of circumstance than of choice. If political intolerance can be said to have any redeeming features, it would be in the enrichment of the intellectual life of those countries not so afflicted, by the en forced migration of scholars of distinction in their chosen fields of study. Among these scholars, Schoenheimer stood pre-eminent. His tragic death on September 11, 1941, must be recorded with sincere regret.The investigations of Schoenheimer and colleagues, involving the use of amino acids and other nitrogenous compounds that had been labeled by the inclusion in their molecules at strategic points of the N15 isotope and of deuterium, permitted a direct attack upon many problems of intermediary metabolism that previously were unsolv able, or that had been incompletely solved by the accumulation merely of indirect or circumstantial evidence. Urinary creatinine was shown indubitably to be derived from tissue creatine, the major mechanism for urea formation was proven to be the ornithine-arginine cycle, the conversion of phenylalanine to tyrosine was found to occur readily 257 Annu. Rev. Biochem. 1942.11:257-282. Downloaded from www.annualreviews.org Access provided by McMaster University on 02/03/15. For personal use only. Quick links to online content Further ANNUAL REVIEWS 258 MITCHELL in the body, even in the presence of an excess of dietary tyrosine, the importance of glutamic and aspartic acids in transamination was es tablished, the conversion of ornithine to proline and glutamic acid was shown to occur, r.nd the anabolic utilization of unnatural isomers by inversion to the natural form was demonstrated with d ( + ) -leucine.Furthermore, new phases in amino acid metabolism were discovered that could only have been suspected previously, such as the irreversi bility of the deamination reaction in volving lysine, as compared with the ready reversibility of the same reaction with leucine, histidine, and many other amino acids. However, the most important discovery of the researches of Schoenheimer and his colleagues with labeled amino acids was the revelation of the existence of a dynamic equilibrium be tween the tissues of the body and the surrounding nutrient media that had not previously been suspected.Schoenheimer & :Kitten berg (1) in a recent review of their work, explain the situation in the following words:The fact that the living organism, in contrast to the dead material, keeps constant the form of the cells and organs as well as the chemical structure of the large molecules has led many investigators to believe that the tissue enzymes, which show their destructive power during autolysis, lie dormant during life and are "activated" only when their functi on is required. The results obtained with isotopes make such a supposition unne...

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The Influence of Plane of Nutrition and of Environmental Temperature on the Relationship between Basal Metabolism and Endogenous Nitrogen Metabolism Subsequently Determined

Cited by 26 publications

References 17 publications

The influence of energy intake on protein metabolism

The influence of energy intake on protein metabolism

Alterations of Protein Metabolism During Cold Acclimation

The Metabolism of Proteins and Amino Acids

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