Fractional composition amino acid

Figure 14 Fluxes and composition of particulate organic carbon in the equatorial Pacific Ocean, (a) POC fluxes (mgm d ). (b) Corresponding fractions of amino acid, carbohydrate, lipid, and molecularly uncharacterized carbon (biochemical class-carbon as a percentage of total OC) in plankton, sediment traps (105 m, l,000m, >3,500 m) and surface sediment samples. The fraction of molecularly uncharacterized organic carbon (calculated as the difference between total OC and the sum of amino acid - - carbohydrate - - Upid) increases with more extensive degradation to become the major constituent in deeper POC samples (after Wakeham et al., 1997). (c) Calculated weight percentages of amino acid, carbohydrate, and lipid in plankton and in sinking (sediment trap) particles in the upper and lower water column as determined by solid-state C-NMR spectroscopy (source Hedges et al., 2001).

Prakash, D. and Pal, M. (1998). Chenopodium Seed protein, fractionation and amino acid composition. Int. J. Food Sci. Nutr. 49, 271-275. 

Rapidly growing cultures (Table 2, exp. phase) show PER values from 2 -10 in most cases,but may increase to 10-30 in some cases. Mague et al. [22] concluded that extracellular release is a normal function of healthy cells and showed that the relative composition of Skeletonema costatum cellular and the extracellular fraction of amino acids was quite different. Marlowe et al. [23] fractionated cellular and extracellular material and found a marked difference in the content of ionic compounds in the two fractions. Myklestad et al. [24] found the reserve polysaccharide P-l,3-glucan to be quite dominating in the soluble cellular fraction of Chaetoceros affinis while the extracellular polysaccharide produced was entirely different and contained no glucose at all in the molecule... 

Casein. Milk contains proteins and essential amino acids lacking in many other foods. Casein is the principal protein in the skimmed milk (nonfat) portion of milk (3—4% of the weight). After it is removed from the Hquid portion of milk, whey remains. Whey can be denatured by heat treatment of 85°C for 15 minutes. Various protein fractions are identified as a-, P-, and y-casein, and 5-lactoglobulin and blood—semm albumin, each having specific characteristics for various uses. Table 21 gives the concentration and composition of milk proteins. 

FIGURE 19.5 The fractional composition of a solution of alanine, a typical amino acid, as a function of pH. Notice that the concentration of the molecular form is extremely low at all pH values its concentration had to be multiplied by a factor of 10 l for it to be visible on the graph. Amino acids are present almost entirely in ionic form in aqueous solution. 

This has a distinct isotopic consequence for the composition of proteins synthesized from these amino acids. To the extent that FAs differ isotopically from the remainder of the diet, this difference is under-represented in proteins partly built up of AAs that caimot be synthesized from an FA precursor. We could represent this difference by a ratio rf, the fraction ofFA-derived C atoms in the AA pool from which proteins are made, divided by the fraction of FA-derived C atoms in the total diet. 

Figure 10.2. Schematic diagram showing how restricted conversion of fatty acids to amino acids influences the fractionation between collagen and CO3 of bone apatite LI = lipid component, PR = protein, T = total isotopic composition AP = COj component of apatite, a) Herbivorous diet (Cj plants only) b) Carnivorous diet, assuming rj = 1 (no barrier to fatty acid conversion to AAs) c) Carnivorous diet, assuming ri < 1 note that carbonate-collagen fractionation is smaller.

Figure 10.4. Effect on apatite-collagen isotopic fractionation due to inhibition of amino acid production and preferred use of exogenous amino acids. Carnivore and herbivore, both based on C3 plants, have similar bulk isotopic composition of total edible tissues (T), leading to similar 5 C for apatite carbonate (AP). Collagen (CO) of carnivore is more enriched in Cthan that of herbivore, because of preferential utilization of amino acids derived from protein (P) of herbivore flesh in construction of carnivore s proteins. C ss = assimilated carbon.

Figure 11.1. A flow-model scheme for treating the protein routing question. Labels refer to flow rates of carbon. The total carbon flux, into and out of the body, is 1, divided into F (for protein) and 1 - F for the remainder. The significant relevant internal fluxes are between the amino acid pool (coupled to the body protein pool), and the energy metabolism pool . The extent to which protein routing is observable in the body protein composition depends on the value ofX (See Fig. 11.2). Numbers in refer to suggested isotopic fractionations associated with a metabolic path, which are consistent with the data of the Ambrose and Norr (1993) and Tieszen and Fagre (1993) data set (see Section 4.1).

SDS-PAGE revealed only one protein band in the purified AE fractions with a MW of 42,000 D (Fig.2). Isoelectric focusing of AE showed that pi > 9. The amino acid composition of the purified AE is shown in table 1. 

Special attention should be paid to polypeptides isolated from a non-diffusible fraction of normal human urine by Boulanger et al. (BIO). By means of paper chromatography they isolated from this mixture seven single polypeptides and determined their amino acid composition. The results of the analyses are given in Table 3. 

High-voltage electrophoresis and subsequent paper chromatography of the fractions obtained made possible the isolation from the analyzed mixture of twenty-two components giving colored spots with ninhydrin and isatin. Among these, fourteen were identified as peptides and their amino acid composition established (Table 5). In the case of eight peptides, also N- and C-terminal amino acids were determined (Table 6). 

Table X. Amino Acid Compositions of Acid Hydrolyzed Protein Fractions from DMSO and Aqueous Extracts of Pondweed and Water Spinach3...

The NPN content has been demonstrated to range from 15 to 37% at harvest (6, 7). The only published report of the composition showed the NPN fraction to be nutritionally unbalanced, containing mostly amino acids and amides (6). The major components were asparagine, 61% aspartic acid, 11% glutamic acid, 4% serine,... 

Now, GC-IRMS can be used to measure the nitrogen isotopic composition of individual compounds [657]. Measurement of nitrogen isotope ratios was described by Merritt and Hayes [639], who modified a GC-C-IRMS system by including a reduction reactor (Cu wire) between the combustion furnace and the IRMS, for reduction of nitrogen oxides and removal of oxygen. Preston and Slater [658] have described a less complex approach which provides useful data at lower precision. Similar approaches have been described by Brand et al. [657] and Metges et al. [659]. More recently Macko et al. [660] have described a procedure, which permits GC-IRMS determination of 15N/14N ratios in nanomole quantities of amino acid enantiomers with precision of 0.3-0.4%o. A key step was optimization of the acylation step with minimal nitrogen isotope fractionation [660]. 

EmUiani C (1966) Paleotemperature analysis of Caribbean core P6304-8 and P6304-9 and a generalized temperature curve for the past 425000 years. J Geol 74 109-126 Emiich K, Ehhalt DH, Vogel JC (1970) Carbon isotope fractionation during the precipitation of calcium carbonate. Earth Planet Sci Lett 8 363-371 Engel MH, Macko SA, SUfer JA (1990) Carbon isotope composition of individual amino acids in the Murchison meteorite. Nature 348 47-49... 

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