Acids, acid normal, definition

Dent s classification is the basis of most classifications of abnormal types of amino aciduria. He divides the pathological conditions into three categories (D9) (A) Overflow amino aciduriain which the blood level of the amino acid concerned is definitely raised above normal [example Section 4.2.1.L (a)] (B) Renal amino aciduria, in which case the blood level is either normal or below normal, and yet the urinary excretion is above normal [tubular reabsorption deficiency example Section 4.2.I.I. (e)] (C) No threshold amino aciduria, in which Dent attributes the condition to an extrarenal disturbance of the metabolism of an amino acid with a high blood clearance, and in which, on account of this latter circumstance, the corresponding blood level may stay normal or is hardly increased. 

Auricchio et al. (A12) analyzed the excretory pattern of 6 children with leukemia and 2 with Hodgkin s disease. No definite relationship could be observed between the disease and the abnormally elevated amounts of tryptophan metabolites. After niacin therapy the urinary excretion of kynurenines and kynurenic and xanthurenic acids was normalized in one case of Hodgkin s disease and in one leukemic subject after pyridoxine administration. 

There is an alternative view of acid-base reactions that relies on the Lewis acid-base definition but has been used to classify a wide range of organic reaction types. Cations are classified as Lewis acids, anions are Lewis bases and salts are viewed as acid-base complexes. When one writes the normal acid-base equation, certain conventions are observed. 

These are the definitions of the two characteristic dissociation constants normally expressed in terms of p K. When three dissociating groups are present in a molecule there are three piC values, ie, pfC, P 3- knowledge of these piC values is important in the separation or isolation of each amino acid by ion-exchange chromatography. 

The last definition has widespread use in the volumetric analysis of solutions. If a fixed amount of reagent is present in a solution, it can be diluted to any desired normality by application of the general dilution formula V,N, = V N. Here, subscripts 1 and 2 refer to the initial solution and the final (diluted) solution, respectively V denotes the solution volume (in milliliters) and N the solution normality. The product VjN, expresses the amount of the reagent in gram-milliequivalents present in a volume V, ml of a solution of normality N,. Numerically, it represents the volume of a one normal (IN) solution chemically equivalent to the original solution of volume V, and of normality N,. The same equation V N, = V N is also applicable in a different context, in problems involving acid-base neutralization, oxidation-reduction, precipitation, or other types of titration reactions. The justification for this formula relies on the fact that substances always react in titrations, in chemically equivalent amounts. 

In the first instance, acidity influences the acid-base equilibria of the reactants. The amine is a Bronsted base. Aniline, a typical substrate, has pKa = 4.6, which means that the protonation shown in Scheme 3-11 is almost complete under normal conditions of diazotization (pH < 1). The base is definitely a much better reagent than the anilinium ion for nitrosation because the latter is an electrophilic substitution. One expects — simply on the basis of the equilibrium shown in Scheme 3-11 — that the rate of diazotization should decrease linearly with increasing acid concentration or, at higher acidities, with the Hammett acidity function h0 (for acidity functions see Rochester, 1970 Cox and Yates, 1983). 

A vitamin is defined as an organic compound that is required in the diet in small amounts for the maintenance of normal metabofic integrity. Deficiency causes a specific disease, which is cured or prevented only by restoring the vitamin to the diet (Table 45-1). However, vitamin D, which can be made in the skin after exposure to sunhght, and niacin, which can be formed from the essential amino acid tryptophan, do not stricdy conform to this definition. 

By means of a procedure described above, Hanson and Fittkau (HI) isolated seventeen different peptides from normal urine. One of them, not belonging to the main peptide fraction, consisted of glutamic acid, and phenylalanine with alanine as the third not definitely established component. The remaining peptides contained five to ten different amino acid residues and some unidentified ninhydrin-positive constituents. Four amino acids, i.e., glutamic acid, aspartic acid, glycine, and alanine, were found in the majority of the peptides analyzed. Twelve peptides contained lysine and eight valine. Less frequently encountered were serine, threonine, tyrosine, leucine, phenylalanine, proline, hydroxyproline, and a-aminobutyric acid (found only in two cases). The amino acid composi-... 

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