Amino acids free pools

Environmental salinity has been shown to alter rates of protein synthesis in fish tissues (Table 2). Studies have been carried out with both stenohaline and eu-ryhaline species protein synthesis rates of the former in response to salinity changes may represent stress responses, whereas in the latter species adaptive responses may be revealed. It is difficult to draw conclusions from the studies in Table 2, as amino acid-free pool-specific radioactivities were not published for any of the studies. 

Statistical Analysis The juice composition, as individual amino acids, free amino nitrogen and ratios of certain amino acids and groups of them were entered into a principal component analysis (PCA) using the SAS (Cary, NC) statistical software. The ratios considered were based on the thinking that relative proportions within the amino pool, rather than absolute quantities between alternative substrates might be related to the level of sulfide formation. 

Trans-inhibition is an additional variable one must consider and correct for when assaying System A activity, especially if the cells have been subjected to a treatment that may alter the intracellular amino acid pools. Generally this problem can be overcome by incubating the control and the treated cells in an amino acid-free medium for 15 to 60 minutes prior to the actual transport assays. This incubation period allows a partial depletion of the intracellulr amino acids and thus minimizes the contribution of trans-inhibition. Of course, the magnitude of the transinhibition and the specific time required to bring the System A activity to a basal level must be determined experimentally for each cell type and for each set of experimental conditions. 

SuperchlorinationShock Treatment. Superchlorination or shock treatment of pool water is necessary since accumulation of organic matter, nitrogen compounds, and algae consumes free available chlorine and impedes disinfection. Reaction of chlorine with constituents of urine or perspiration (primarily NH" 4, amino acids, creatinine, uric acid, etc) produces chloramines (N—Cl compounds) which are poor disinfectants because they do not hydrolyze significantly to HOCl (19). For example, monochloramine (NH2CI) is only 1/280 as effective as HOCl against E. coli (20). 

Under physiologic conditions in the human adult, 1—2 X 10 erythrocytes are destroyed per hour. Thus, in 1 day, a 70-kg human turns over approximately 6 g of hemoglobin. When hemoglobin is destroyed in the body, globin is degraded to its constiment amino acids, which are reused, and the iron of heme enters the iron pool, also for reuse. The iron-free porphyrin portion of heme is also degraded, mainly in the reticuloendothehal cells of the liver, spleen, and bone marrow. 

More data are needed on the effects of organic practices on phytochemicals and their precursors. How does modification of precursor pools affect biosynthesis For example, see studies on the effects of lower levels of free amino acids caused by a reduction in nitrogen input. 

Several different types of proteases hydrolyze intact storage proteins first into large fragments and then into smaller peptides and amino acids within the protein body. The peptides are transported to the cytosol where other enzymes, e. g. amino-peptidases, carboxypeptidases, dipeptidases and tripeptidases, cleave them and eventually form a pool of free amino acids [11]. 

Simply on the basis of the normal composition of marine organisms, we would expect proteins and peptides to be normal constituents of the dissolved organic carbon in seawater. While free amino acids might be expected as products of enzymic hydrolysis of proteins, the rapid uptake of these compounds by bacteria would lead us to expect that free amino acids would normally constitute a minor part of the dissolved organic pool. This is precisely what we do find the concentration of free amino acids seldom exceeds 150 xg/l in the open ocean. It would be expected that the concentration of combined amino acids would be many times as great. There have been relatively few measurements of proteins and peptides, and most of the measurements were obtained by measuring the free amino acids before and after a hydrolysis step. Representative methods of this type have been described [245-259]. Since these methods are basically free amino acid methods, they will be discussed next in conjunction with those methods. 

Graney, R.L. and J.P. Giesy, Jr. 1986. Effects of long-term exposure to pentachlorophenol on the free amino acid pool and energy reserves of the freshwater amphipod Gammarus pseudolimnaeus Bousfield (Crustacea, Amphipoda). Ecotoxicol. Environ. Safety 12 233-251. 

DOM is also released into seawater by phytoplankton fiar reasons that are as yet imclear. On average, 13% of the phytoplankton carbon is released as exudates, some of which are low-molecular-weight compounds, such as free amino acids and tricarboxylic acids. Other exudates are high-molecular-weight compoimds, such as the acylated heteropolysaccharides. These macromolecules are relatively chemically resistant and appear to form a large portion of the HMW DOC pool. 

MacdowalP found that tobacco leaves were most susceptible to injury by ozone (at 0.035 ppm for 5 h) just after full leaf expansion. This point corresponded to the banning of the decline in protein content. Lee modified the nitn en content of tobacco leaves by supplying urea and found a positive correlation of injury caused by ozone (at 1 ppm for 5 h) with nonprotein nitrogen, but not with protein. This result is in contrast with that of Ting and Mukeiji, who found that, in cotton leaves (in which the period of maximal susceptibility was at about 75% of full leaf expansion), the amino acid pool was low at the time of maximal susceptibility. However, ozone treatment (0.7 ppm for 1 h) increased the free amino acid pool. 

There are four sources of amino acids that enter the free amino acid pool in the body proteins in food proteins secreted into the stomach and intestine by the digestive glands endogenous proteins and microorganisms that die and release their protein in the colon. 

The toxic effects of ozone in plant systems have been studied for some time, yet the actual mechanisms of injury are not fully understood. In addition to visible necrosis which appears largely on upper leaf surfaces, many other physiological and biochemical effects have been recorded ( ). One of the first easily measurable effects is a stimulation of respiration. Frequently, however, respiration may not increase without concomitant visible injury. Furthermore, photosynthesis in green leaves as measured by CO2 assimilation, may decrease. It is well known that ozone exposure is accompanied by a dramatic increase in free pool amino acids ( ). Ordin and his co-workers ( ) have clearly shown the effect of ozone on cell wall biosynthesis. In addition, ozone is known to oxidize certain lipid components of the cell ( ), to affect ribosomal RNA (16) and to alter the fine structure of chloroplasts (7 ). 

The amino acid pool is defined as all the free amino acids in cells and extracellular fluid. 

A Golan-Goldhirsch, AM Hogg, FW Wolfe. Gas chromatographic analysis of the free amino acid pool of the potato and gas chromatography-mass spectrometry identification of y-aminobutyric acid and ornithine. J Agric Food Chem 30 320-323, 1982. 

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