Amino acids available

In nature, there are 20 amino acids available for incorporation into the protein chain. They are arranged in a specific and characteristic sequence along the molecule. This sequence is generally referred to as the primary structure of the protein. Also part of the primary structure is the relative molar mass of the macromolecule. 

Experimental Procedures. Nutrient bioavailability is a complex subject when applied to protein components. In fact, it is an error to speak of the bioavailability of the protein rather one must consider the availability of the individual amino acids which make up the protein. Amino acid availability implies sufficient digestion of the protein in the intestines to allow absorption into the tissue. Then, in the case where... 

The influence of processing on amino acid availability may be profound, especially under extreme conditions. Processing can increase amino acid availability, often by increasing digestibility or inactivating antinutritional factors. Processing may also serve to decrease amino acid availability. 

Protein hydrolysis in 6N HCl and subsequent analysis to determine amino acids (except tryptophan, which is acid labile) chemically present is a first step in protein quality evaluation. The chemical score and the EAA index represent attempts to use this information to chemically estimate nutritional quality of protein their obvious limitation is their disregard for amino acid availability. The chemical score is obtained by evaluating the percent of the limiting amino acid in comparison to that amino acid in whole egg protein ). The EAA index is the geometric mean of the ratios of each of the essential amino acids to those amino acids occurring in whole egg (4). 

Another method of protein treatment involves enzymatic modification. Enzymes per se may be added or the protein may be subjected to the microbial enzymes produced from fermentation. There is little evidence to indicate that the amino acid availability is influenced by these treatments, although one might expect benefits from increased... 

Little information is available regarding potential nutrient interaction and amino acid availability in soybeans. Bau and Debry (55) have investigated how other nutrients in a product could affect amino acid availability. Attempting to refine the protein from germinated and ungerminated soybean. 

Wheat Products and Amino Acid Availability. As a protein source, wheat is limited by its content of lysine. 

Nevertheless, it is an important source of protein for humans. Processing of wheat is necessary before use, and thermal processing is often employed in some manner. Much information is available regarding the effects of milling on nutrients in wheat, but little work has been done regarding the effects of heat treatment on amino acid availability. 

Cottonseed Processing and Amino Acid Availability. The inherent protein quality of cottonseed is good (62,63). 

Processing of Sesame Protein and Amino Acid Availability. 

Processing of Rapeseed Protein and Amino Acid Avail-... 

As stated earlier, rRNA synthesis is usually maintained at a rate proportional to the gross rate of protein synthesis. In a normal wild-type cell, when protein synthesis is limited (e.g., by amino acid availability), M. Cashel and J. Gallant have shown that the ppGpp concentration rises rapidly from about 50 pM to 500 /uM (fig. 30.16). Concomitantly, rRNA synthesis ceases abruptly. This is part of the phenotype known as the stringent response First, amino acid deprivation or other factors that slow down protein synthesis provoke an increased rate of accumulation of ppGpp thisin turn leads to an inhibition of rRNA synthesis. 

Our study successfully demonstrated that increases in ethanol production and increases in protein level of HDG can be achieved with less severe pretreatment of DG and subsequent fermentation of the pretreated DG to produce HDG. The HDG residue had a crude protein content near 61 wt%, comparing favorably with soybean meal, which has a range of 44-52 wt%. The total amount of digestible amino acids available to turkey poults in HDG was comparable to NRC feeds (26), with the exception of the levels of lysine. 

Mild exercise produced by swimming rats for one hour decreased protein synthesis by 17. While more intense treadmill running reduced synthesis by 30 and an exhaustive run of three hours inhibited synthesis by 70. These data suggest that exercise may produce a catabolic condition in muscles which would make amino acids available for oxidation and that this effect is dependent on the Intensity and duration of the exercise. 

Although the two methods introduced in Section 28.3 for resolving racemic mixtures of amino acids make enantiomerically pure amino acids available for further research, half of the reaction product is useless because it has the undesired configuration. Moreover, each of these procedures is costly and time-consuming. 

Amino acids have probably formed in different places of the Solar system through processes independent of living organisms as shown by their occurrence in carbonaceous chondrites, a particular class of meteorites. Among these processes, only a particular subset of them can be considered to be truly prebiotic. It is the processes that make amino acids available in environments capable of developing a complex chemistry compatible, or at least presumed to be compatible, with the emergence of life. 

Encyclopedia of Amino Acids. Available at www.ajinomoto.com/amino/index.html. 

Hyde, R., Cwiklinski, E.L., Macaulay, K., Taylor, P.M., and Hundal, H.S. (2007) Distinct sensor pathways in the hierarchical control of SNAT2, a putative amino acid transceptor, by amino acid availability. The Journal of Biological Chemistry. 282 (27), 19788-19798. 

Q.4.7 You have 20 amino acids available. How many pentapeptides can be made if an amino acid is not replaced after being used ... 

Bernlohr and Novelli reported that, although the mechanism of antibiotic synthesis differs from protein synthesis, there appears to be a competition between the two processes for the amino acids available in the cell. During active cellular growth with high protein synthesis, practically no bacitracin was produced. In contrast, bacitracin synthesis was high, when the requirements for protein synthesis were low, as at the end of the log phase or when protein synthesis was inhibited. The production of bacitracin, and some other antibiotics, seems to be related in some way to the sporeforming metabolism . In this phase a great part of the cell wall is dissolved, while protein production remains very low. 

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