Protein from nitrogen analysis

Table n shows the changes in the composition of the bacterial substance which occur when 100 mg. of log cells at the depletion point grow into valine cells (if that is the limiting amino acid), or into threonine cells if threonine is limited. The amounts formed from 100 mg. at the point of depletion average 145 mg. in the case of valine and 190 mg. in the case of threonine. The determination of wall substance by mechanical disruption and the determination of membrane substance by lipide analysis have been outlined. The other data are obtained by way of conventional procedures DNA (deoxyribonucleic acid) by diphenylamine, and completely independently by thymine RNA (ribonucleic acid) by ultraviolet extinction and cytoplasmic protein from nitrogen determinations corrected for the nitrogen content of the other components. 

N. Giraud, M. Blackledge, M. Goldman, A. Bockmann, A. Lesage, P. Penin, L. Emsley, Quantitative analysis of backbone dynamics in a crystalline protein from nitrogen-15 spin-lattice relaxation,). Am. Chem. Soc. 127 (2005) 18190-18201. 

The correct /V-factor for protein found in herbaceous biomass will likely be different than 6.25. Yet, determining a perfectly accurate N-factor for the complex matrices of biomass feedstock and process samples may not be possible. The challenge is then to determine the most accurate N-factor possible for biomass feedstock and process samples. A strategy based on the consensus in the literature has been incorporated into the portfolio methods. These methods calculate the reasonable N-factor upper and lower limits for a given material. The limits are calculated using data from an amino acid (AA) analysis with multiple hydrolysis times and an accurate total nitrogen analysis substantially similar to the methods described by Mosse.127... 

New interest in the nature of the constituent serum proteins resulted from the introduction of the sodium sulfate fractionation scheme by Howe (H24, H25). This was a technical advance because, unlike ammonium sulfate, sodium sulfate need not be removed prior to nitrogen analysis, the only accurate available means at that time of determining protein. Howe (H24) observed three ranges of sodium sulfate concentration at which an increase in molarity of 0.05 in a 1 30 dilution of calf serum failed to produce the expected increase in precipitation. One of these critical concentrations occurred at 1.45-1.50 M and was thought to indicate complete globulin precipitation. 

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