Protein utilization

Net protein utilization (NPU) = %digestibility (D) x biological value(BV) complete utilization = 100. Biological value is given in parentheses ... 

MARIOTTI F, MAKE S, BENAMOUZIG R, LUENGO 0, DARE S, GAUDICHON 0, TOME D (1999) Nutritional value of [15N]-soy protein isolate assessed from ileal digestibility and postprandial protein utilization in humans. /AmZ 129 1992-7. 

MYER R o, FROSETH J A, COON 0 N (1982) Protein utilization and toxic effects of raw beans (Phaseolus vulgaris) for young pigs. . 1 Anim Sci. 55 1087-98. 

Bradford, M. M. (1976). A rapid and sensitive method for the quantitation of microgram quantities of protein utilizing the principle of protein-dye binding. Anal. Biochem. 72, 248-254. 

WOLF, B.P., SUMNER, L.W., SHIELDS, S.J., NIELSEN, K., GRAY, K.A., RUSSELL, D.H., Characterization of proteins utilized in the desulfurization of petroleum products by matrix-assisted laser desorption ionization time-of-flight mass spectrometry, Anal. Biochem., 1998,260,117-127. 

As with any metalloprotein, the chemical and physical properties of the metal ion in cytochromes are determined by the both the primary and secondary coordination spheres (58-60). The primary coordination sphere has two components, the heme macrocycle and the axial ligands, which directly affect the bound metal ion. The pyrrole nitrogen donors of the heme macrocycle that are influenced by the substitutents on the heme periphery establish the base heme properties. These properties are directly modulated by the number and type of axial ligands derived from the protein amino acids. Typical heme proteins utilize histidine, methionine, tyrosinate, and cysteinate ligands to affect five or six coordination at the metal center. 

Data for the metabolites in plasma are generally for the unbound forms, but there is ample evidence that PPT bind noncovalently to proteins. Most studies on PPT-protein interaction have focused on protein utilization or astringency but a few studies have addressed binding to plasma proteins and lipoproteins. " " Strongest binding has been associated with 1,2-dihydroxyphenols and proline-rich proteins such as those character-istic of human saliva and structure-activity relationships have been reported. 

Normal dietary exposure over many years has highlighted two areas of concern arising through PPT binding of nutrients in the gastrointestinal tract. Impaired absorption of trace metals and impaired protein utilization have been referred to above. 

For example, the UHT heat treatment results in some protein dena-turation, but the biological value and net utilization of milk proteins remain essentially unaffected (Katz et al. 1981 Ford and Thompson 1981 Mehta 1980). In fact, UHT milk may be more digestible than raw or conventionally pasteurized milk because of the greater protein denaturation. The results of both animal feeding studies and studies of human infants indicate that the protein utilization of UHT milk is at least as high as that of conventionally pasteurized milk (Renner 1980 Katz et al. 1981). 

M. Bradford, Anal. Biocbem. 72,248-254 (1976). A Rapid and Sensitive Method for the Quantitation of Microgram Quantities of Protein Utilizing the Principle of Ligand-Dye Binding. ... 

Alternate Protocol 4 Net Protein Utilization (NPU) and Biological Value... 

Determining protein quality analysis is important in food science, particularly for developing foods with targeted nutritional value, and in animal feeding and husbandry. Protein is the key component in the diet of any farmed species, particularly in aquaculture and the pet food industry, making an accurate assessment of protein utilization critically important. Protein quality analysis provides an estimate of the content and bioavailability of indispensable or dietary essential amino acids. 

Net protein ratio (NPR) is used to correct PER values for the amount of protein required for cell maintenance. NPR is often run in conjunction with a PER. The experiment requires that one additional set of animals be added as a treatment group. This group of animals is fed a basal diet with no protein (zero protein or basal diet). Results from RNPR are similar to net protein utilization (NPU) and biological value (BV methods, see Alternate Protocol 4). A 2-week RNPR is thought to be the most appropriate rat test for routine assessment of protein quality. 

---