Amino acid value

In comparison with values from the literature, the majority of the amino acid values for our collagen standard (3 replicates) are within acceptable... 

In Table 10 is given a summary of the uric acid and amino acid values obtained from repeated samples from 9 individuals of both sexes, all collected in the same manner. 

Unfortunately, there are numerous ways to circumvent the analysis of total amino acids, such as by the addition of ammonium salts, inexpensive amino acids, peptides and protein hydrolysates. Several approaches have been made to verify the authenticity of the total amino acid values. Rockland and Underwood (10) developed a paper chromatographic technique for quantitatively estimating the individual amino acids. 

Wallrauch (70) suggested a different approach to detecting altered amino acid values. Since proline (without the primary amino group) does not react with formaldehyde, the ratio of proline to the formol number is a potentially useful indicator of adulteration. The average ratio was found to be 19 with a standard deviation of 5. 

The isolated proteinaceous surfactants, obtained from commercial agarose powder and forest soil extract, were found to have extremely similar total amino acid compositions. Table 4.2 summarizes the amino acid values obtained from four determinations for each of the two surfactant preparations it can be seen that the rather unusual amino acid ratios obtained (among 17 different amino acids) for the two separate cases closely resemble one another. Specifically, in both of these cases the relative amounts of the different amino acids identified (excluding tryptophan which is completely destroyed during acid hydrolysis) were as follows glycine serine > aspartic acid (and/or aspara-... 

Table 5.1 lists the amino acid values obtained from the individual determinations for peaks I and III. Agreement between individual trials was excellent for the dominant peak I, and mostly very good for peak III where less proteinaceous material was available for analysis. Judging from the obvious absence of proline in peak III, it may well be the case that the material contained in this late-eluting (Fig. 5.3) peak, having a total amino acid composition (except for proline) somewhat similar to peak I, represents a partial degradation product (or several products) of the... 

To test this hypothesis, the only method available in the early SO s was a crude approximation arrived at by tabulating all the amino acid values in terms of molar ratios of aspartic acid, and from the 16 pro-... 

Recoveries based on sequencing yields were calculated from PTH-amino acid values in the first or second cycle for each peptide. The values for the in-gel and PVDF methods were compared to the values obtained in-soIution. The pmol recovery for the in-gel method was considerably higher for 4 out of 6 peptides. Total recovery was significantly higher for the in-gel method compared to the PVDF method (Table II). Again, it should be noted that sequencer recoveries are not quantitative, and an absolute comparison of peptide yields may not be made due to differences in enzymatic digestion. 

AAA showed 66 of 82 crude products to be compositionally correct (Trp was not quantitated). Only one product had a complete deletion, corresponding to a des(Val,Lys,Arg) peptide synthesized by Boc chemistry. Of the other 15 samples that were not compositionally correct, 13 showed at least a low Lys value, often accompanied by a low Ser, Thr, and/or Arg value. Based on sequence analysis and mass spectrometric results (see later discussion), neither the low Lys nor other low amino acid values could be demonstrated, indicating that AAA of crude peptides may sometimes suffer interference from scavengers used during peptide-resin cleavage. A similar effect was seen in the 1993 ABRF PS study (3). 

Beriver, C. K Gregory, D. M Sovetts, D, and Tissenbaum, C. (1985). Normal plasma amino acid values in adults The influence of some common physiological variables. Metabolism 34, 868-873. 

Amino acid values are expressed as mole %. a mean values of three separate measurements b extrapolated to zero time hydrolysis c not determined. Reprinted with permission from ref. 7. 

Tables B.1-B.4 list the amino acid values in blood, urine, CSF and vitreous fluid and are included as a guideline. However, it should be noted that even when using the same instrumentation the reference values may vary from laboratory to laboratory. Most often, each laboratory establishes its own reference ranges.

Table B.8. Effects of age/physiological changes/toxins on amino acid values...

Gregory DM, Sovetts D, Clow CL, Scriver CR. Plasma free amino acid values in normal children and adolescents. Metabolism 1986 35(10) 967-969. 

The inherited enzyme deficiencies listed in Table 11.2 lead to the accumulation of substrates and deficiencies of products. For correct interpretation of laboratory results, one need be aware that substrate accumulation can affect the prior enzyme in the pathway (e.g. increased carbamyl phosphate inhibits CPS). A deficiency of urea cycle intermediates (transport or enzyme products or dietary substances) e.g. arginine or ornithine, is often rate limiting. It can initiate a vicious cycle, which worsens the urea synthetic capacity in the cytosol (e.g. by limiting protein synthesis), or in the mitochondria (deficient stimulation of NAGS and of substrate for OTC). Measured plasma values reflect cytosolic metabolite concentrations, not those of mitochondria. Protein catabolism contributes to the plasma amino acid values. Thus, the interpretation of results for plasma arginine, proline and lysine must be done within the context of the pattern found for all of the amino acids. Urea concentrations depend upon the arginine in the cytosol originating from protein catabolism, urea cycle synthesis, and therapeutic applications. 

All amino acid values are given as % of total residues ND, not determined [kDa] indicates the M, CH [%] the carbohydrate content value for protein lacking carbohydrate given... 

The reaction of l,3-diphenylprop-2-enyl acetate (3) with dimethyl malonate to give (4) is catalysed by Pd complexes containing chiral imine-sulfide chelate ligands (5) derived from amino acids. Values of ee around 90% were realised in the most favourable cases. The steric and electronic factors which underlie the high enan-tioselectivity were examined by experiments involving about 12 different ligands (i.e. various R, R, R ). It was concluded that the enantioselectivity is ultimately controlled by the subtle steric environment of the chiral imine-sulfur chelate ligand, which predisposes the allyl unit of the reaction intermediate to a preferred reaction trajectory. ... 

Percentage w/w Amino Acid Values for Specific Subfractions of Whey Protein... 

---