Dietary protein human

Dietary phosphorus exerts variable influence on calcium loss depending on the nature of the dietary protein. Humans fed food containing abundant phosphorus to calcium excreted little more calcium unless the meat content of the diet changed markedly. 

Ambrose, S.H. and Norr, L. 1993 Experimental evidence for the relationship of the carbon isotope ratios ofwhole diet and dietary protein to those ofbone collagen and carbonate. In Lambert, J.B. and Grupe, G., eds.. Prehistoric Human Bone Archaeology at the Molecular Level. Berlin, Springer-Verlag 1-37. 

Since this increased calcium loss, the quality of dietary protein may be important in conserving body calcium in the bone reservoir via the kidney. Human renal studies have corroborated animal data in-so-far as calcium excretion as influenced by urinary acidity is concerned. This was emphasized by Marone et al. (15) who reported increased excretion of calcium in the acidotic dog and by Zemel, et al. (27) who studied calcium filtration by the kidney. They fed subjects low or high-protein (50 or 150 g/d) diets, then compared... 

Effect of Dietary Protein, Calcium, and Phosphorus on Calcium Metabolism in Humans... 

From a global view, plant protein sources (cereals, legumes, oilseeds, vegetables, fruits) have always been the primary source of dietary energy and protein for the majority of the world s population. In addition, in recent years, the use of vegetable protein products as sources of dietary protein, as supplements, and as extenders of more traditional animal protein sources has been increasing markedly in the developed countries. These factors are responsible for our interest in determining the effects of plant protein sources on the utilization of minerals in the human diet. 

Aflatoxin Bi (AFB) is a mold metabolite which has been observed to be acutely toxic and carcinogenic to a wide variety of animals (5,6) and has been implicated in human primary hepatic carcinoma (7, 8). Diets deficient in protein have been reported to increase the susceptibility of mammals to acute AFB toxicity and the induction of cancer (2, 9, 10, 11, 12, 13). Increased dietary proteins have increased the carcinogenic activity of AFB fed to rats (1 4) and trout (15.). Supportive of this latter finding has been the reported direct relationship between dietary protein content and AFB-DNA adduct formation in vivo in rats (16, 17). 

All human tissues are capable of synthesizing the nonessential amino acids, amino acid remodelling and conversion of non-amino-acid carbon skeletons into amino acids and other derivatives that contain nitrogen. However, the liver is the major site of metabolism of nitrogenous compounds in the body. Dietary proteins are the primary source of essential amino acids (or nitrogen). Digestion of dietary proteins produces amino acids, which are absorbed through epithelial cells and enter the blood. Various cells take up these amino acids that enter the cellular pools. 

A distribution of amino acids in dietary proteins can be obtained accordingly by taking both animal and plant proteins at a ratio of 1 3-4. Although plant proteins are lower cost, they are markedly deficient in some essential amino acids. Their protein efficiency is low without addition of deficient ammo acids. Enrichment of human and animal diets with free amino acids, such as lysine, methionine, threonine, and tryptophan, as a substitute for animal proteins, has proved successful. 

Ushirogawa, Y. 1992. Effect of organic acids, trypsin inhibitors and dietary protein on the pharmacological activity of recombinant human granulocyte colony-stimulating factor (rhG-CSF) in rats. Int J Pharm 81 133. 

Takada, K., et al. 1991. Effect of pH, dietary proteins and trypsin inhibitors on hydrolytic rate of human granulocyte colony-stimulating factor (G-CSF) by rat digestive enzymes. J Pharmacobio-dyn 14 363. 

The serine proteases are a dass of proteolytic enzyme (they catalyze the hydrolysis of either ester or peptide bonds in proteins) that require an active site residue for covalent catalysis. The active site residue, the catalytic Ser-195, is particularly activated by hydrogen-bonding interactions with His-57 and Asp-102. Crystal structures show that Ser-195, His-57, and Asp-102 are dose in space. Together these three residues, which are located in the substrate binding (SI) pocket, form the famed catalytic triad of the serine proteases. In humans and mammals serine proteases perform many important functions, especially the digestion of dietary protein, in the blood-dotting cascade, and in the complement system ... 

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