Whole-rat protein content estimation: applicability of the N × 6·25 factor
Open Access
- 1 August 1994
- journal article
- Published by Cambridge University Press (CUP) in British Journal of Nutrition
- Vol. 72 (2), 199-209
- https://doi.org/10.1079/bjn19940024
Abstract
The amino acid composition of the protein from three strains of rat (Wistar, Zucker lean and Zucker obese), subjected to reference and high-fat diets has been used to determine the mean empirical formula, molecular weight and N content of whole-rat protein. The combined whole protein of the rat was uniform for the six experimental groups, containing an estimate of 17.3% N and a mean aminoacyl residue molecular weight of 103.7. This suggests that the appropriate protein factor for the calculation of rat protein from its N content should be 5.77 instead of the classical 6.25. In addition, an estimate of the size of the non-protein N mass in the whole rat gave a figure in the range of 5.5 % of all N. The combination of the two calculations gives a protein factor of 5.5 for the conversion of total N into rat protein.Keywords
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