Nitrogen factor

PER) was modified in several respects. The diets were calculated on a 10 percent protein level rather than on an isonitrogenous basis. This was done because the nitrogen factors of the various blend components varied appreciably from the 6.25 nitrogen factor assumed in the AOAC procedure. A composite nitrogen factor for each blend was calculated from analytical results by dividing the total amino acid content by the nitrogen content. In this manner,... 

Stokinger, H. E. Evaluation of the hazards of ozone and oxides of nitrogen. Factors modif g toxicity. A.M.A. Arch. Ind. Health 15 181-190, 1957. 

Sprent, J. I. and McKey, D. 1994. Advances in Legume Systematics. Part 5. The Nitrogen Factor. Kew The Royal Botanic Gardens. 

Meat products, rmder regulations, are defined according to meat content and this may be calculated from compositional data. The percentage fat-free meat is calculated from the total nitrogen content (corrected for any nomneat nitrogen) using nitrogen factors specific for meat of each species. Meat content is calculated as the fat-free meat plus the fat. 

Protein synthesis. Cohen has also endeavored to measure protein synthesis in the infected system by taking the difference of the total N minus DNA-N (52,54,62). This procedure is open to question on several counts. For example, proteolysis occurs as is indicated by the dip in the protein N curve of Fig. 6. Also, DNA is measured as deoxypentose by the diphenylamine reaction and a nitrogen factor has had to be assumed which takes no account of the possibility that the sugar may be accumulating in some form other than DNA. Consequently, the argument that the ratio of the rates of increment of N and P utilization (54) is similar to that of normal cells is a matter still open to question as inspection of Fig. 6 will reveal The same criticism attaches to the conclusion mentioned above that only virus or virus components are synthesized. 

In addition to inadequate separations by the Howe method, there is the further problem of the inadequacy of the conventional factor 6.25, which is generally applied to all fractions to convert from grams protein nitrogen to grams dried protein. The average nitrogen factor found experimentally in the dried proteins of pooled normal human plasma (5) is 6.73. The conversion factor of individual proteins (5) varies from 6.10 to 8.40. 

The first quantitative studies of the nitration of quinoline, isoquinoline, and cinnoline were made by Dewar and Maitlis, who measured isomer proportions and also, by competition, the relative rates of nitration of quinoline and isoquinoline (1 24-5). Subsequently, extensive kinetic studies were reported for all three of these heterocycles and their methyl quaternary derivatives (table 10.3). The usual criteria established that over the range 77-99 % sulphuric acid at 25 °C quinoline reacts as its cation (i), and the same is true for isoquinoline in 71-84% sulphuric acid at 25 °C and 67-73 % sulphuric acid at 80 °C ( 8.2 tables 8.1, 8.3). Cinnoline reacts as the 2-cinnolinium cation (nia) in 76-83% sulphuric acid at 80 °C (see table 8.1). All of these cations are strongly deactivated. Approximate partial rate factors of /j = 9-ox io and /g = i-o X io have been estimated for isoquinolinium. The unproto-nated nitrogen atom of the 2-cinnolinium (ina) and 2-methylcinno-linium (iiiA) cations causes them to react 287 and 200 more slowly than the related 2-isoquinolinium (iia) and 2-methylisoquinolinium (iii)... 

The use of oximes as nucleophiles can be quite perplexing in view of the fact that nitrogen or oxygen may react. Alkylation of hydroxylamines can therefore be a very complex process which is largely dependent on the steric factors associated with the educts. Reproducible and predictable results are obtained in intramolecular reactions between oximes and electrophilic carbon atoms. Amides, halides, nitriles, and ketones have been used as electrophiles, and various heterocycles such as quinazoline N-oxide, benzodiayepines, and isoxazoles have been obtained in excellent yields under appropriate reaction conditions. 

The nucleophilicity of amine nitrogens is also differentiated by their environments. In 2,4,5,6-tetraaminopyrimidine the most basic 3-amino group can be selectively converted to a Schiff base. It is meta to both pyrimidine nitrogens and does not form a tautomeric imine as do the ortho- and /xira-amino groups. This factor is the basis of the commercial synthesis of triamterene. 

The little-studied conjugated base of 2-aminothiazoles is able to react on either ring nitrogen or exocvclic nitrogen. Steric hindrance of R2 and R. is clearly an important factor in this reactivity (Scheme 147). 

The steric effects of alkyl substituents (R= methyl, ethyl, i-propyl, f-butyl) on the nitrogen have been related to the steric factors of these same groups as measured in kinetic studies (152). 

The shape of a large protein is influenced by many factors including of course Its primary and secondary structure The disulfide bond shown m Figure 27 18 links Cys 138 of carboxypeptidase A to Cys 161 and contributes to the tertiary structure Car boxypeptidase A contains a Zn " ion which is essential to the catalytic activity of the enzyme and its presence influences the tertiary structure The Zn ion lies near the cen ter of the enzyme where it is coordinated to the imidazole nitrogens of two histidine residues (His 69 His 196) and to the carboxylate side chain of Glu 72... 

Examination of these and other results indicates that the value of a for a given adsorptive which needs to be used in order to arrive at a value of specific surface consistent with that from nitrogen adsorption, varies according to the nature of the adsorbent. The existence of these variations shows that the conventional picture, in which the value of a corresponds to a monolayer which is completely filled with adsorbate molecules in a liquidlike packing, is over-simplified. Two factors can upset the simple picture (a) there may be a tendency for adsorbed molecules to become localized on lattice sites, or on more active parts of the solid surface and (b) the process... 

Cotton linters or wood pulp are nitrated using mixed acid followed by treatment with hot acidified water, pulping, neutralization, and washing. The finished product is blended for uniformity to a required nitrogen content. The controlling factors in the nitration process are the rates of diffusion of the acid into the fibers and of water out of the fibers, the composition of mixed acid, and the temperature (see Cellulose esters, inorganic esters). 

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