Amino acid exercise

Although BCAAs are essential amino acids, exercise promotes their oxidation to generate ATP in skeletal muscle (Chapter 46). Reports suggest athletes benefit from supplements of BCAAs before and after exercise to decrease exercise-induced muscle damage and enhance synthesis of muscle proteins. 

A pair of amino acids is separated in a column in which the stationary phase is saturated with water and the carrier solvent is methanol, CH,OH. The more polar the acid, the more strongly it is adsorbed by the stationary phase. The amino acids that were separated in this column are (a) HOOCCHNH2CH,COOH and (b) HOOCCHNH2CH(CH,)2. Which amino acid would you expect to be eluted first Explain your reasoning. Refer to Major Technique 4 on chromatography, which follows these exercises. 

Factors that stimulate glucagon secretion include a decrease in blood glucose an increase in blood amino acids sympathetic nervous stimulation stress and exercise. Factors that inhibit glucagon secretion include insulin and an increase in blood glucose. Table 10.2 summarizes the major functions of the hormones discussed in this chapter. 

If opiates are such addictive and potentially lethal compounds, why does the body respond to them As with the cannabinoids (Chapter 7), it has been discovered that the body and brain possess numerous opiate-specific receptor sites. As many as nine receptor subtypes have been identified, with three of them being the most important p (mu), k (kappa) and 8 (delta). The finding that the distribution of opiate receptors did not parallel the distribution of any known neurotransmitter prompted the search for and identification of a number of endogenous compounds specific to these receptors. These enkephalins and endorphins are manufactured within the brain and other body systems (especially the gut and intestines) and form the body s natural response to pain. They appear to be produced in bulk chains of amino acids called polypeptides , with each active neurotransmitter being composed of around five amino acid molecules. These active neurotransmitters are subsequently cleaved from the larger polypeptides at times of demand for example, it has been demonstrated that the plasma levels of these active compounds rise during childbirth, traumatic incidents and vigorous physical exercise. 

Carbon atoms from amino acids are usedin GNG during fasting and starvation, but during vigorous exercise, skeletal muscle provides substantial amounts of lactate... 

The calorific capacity of amino acids is comparable to that of carbohydrates so despite their prime importance in maintaining structural integrity of cells as proteins, amino acids may be used as fuels especially during times when carbohydrate metabolism is compromised, for example, starvation or prolonged vigorous exercise. Muscle and liver are particularly important in the metabolism of amino acids as both have transaminase enzymes (see Figures 6.2 and 6.3 and Section 6.4.2) which convert the carbon skeletons of several different amino acids into intermediates of glycolysis (e.g. pyruvate) or the TCA cycle (e.g. oxaloacetate). Not all amino acids are catabolized to the same extent... 

In a muscle at rest, most of the 2-oxo acids produced from transamination of branched chain amino acids are transported to the liver and become subject to oxidation in reactions catalysed by branched-chain 2-oxo acid dehydrogenase complex. During periods of exercise, however, the skeletal muscle itself is able to utilize the oxo-acids by conversion into either acetyl-CoA (leucine and isoleucine) or succinyl-CoA (valine and isoleucine). 

In a similar exercise with D-methionine, Findrik and Vasic-Racki used the D-AAO of Arthrobacter, and for the second-step conversion of oxoacid into L-amino acid, used L-phenylalanine dehydrogenase (L-PheDH), which has a sufficiently broad specificity to accept L-methionine and its corresponding oxoacid as substrates. Efficient quantitative conversion in this latter reaction requires recycling of the cofactor NAD into NADH, and for this the commercially available formate dehydrogenase (FDH) was used (Scheme 2). 

Protein represents the second largest store of chemical energy in the body, but it is not used for generating ATP except in some diseases and in some extreme conditions (e.g. prolonged starvation, very sustained exercise). The largest deposit of protein in the body is in skeletal muscle (about 40% of body weight). The synthesis of proteins requires amino acids whereas degradation of proteins pro-... 

Compounds that stimu late insulin secretion One that decreases insulin secretion A rise in blood glucose is the most important signal for increased insulin secretion. Plasma amino acid levels and the intestinal peptide secretin also stimulate insulin secre tion. Its synthesis and release are decreased by epinephrine, which is secreted in response to stress, trauma, or extreme exercise. 

The application of the primary databases and structural analytical tools will be introduced using a protein from a future experiment. In Experiment 4, you will extract, purify, and characterize a-lactalbumin from bovine milk. To prepare for this activity, here you will learn about the structure of a related protein, a-lactalbumin from humans. We will search databases to find and view its primary and secondary structure and also determine if there are other proteins with a similar amino acid sequence and structure. After completion of these exercises, you will be able to apply these computer tools to proteins of your own choice. 

Exercise 15-42 The amino acid methionine is a methyl donor in biological methyla-tion of hydroxyl groups. However, direct methylation has an unfavorable free energy change ... 

Exercise 25-1 Select the amino acids in Table 25-1 that have more than one chiral center and draw projection formulas for all the possible stereoisomers of each which possess the L configuration at the a carbon. 

Exercise 25-2 Which of the amino acids in Table 25-1 are acidic amino acids and which basic amino acids Which of the structures shown would have the most basic nitrogen The least basic amino nitrogen Give the reasons for your choices. (Review Section 23-7.)... 

Exercise 25-8 The reactions that lead to the blue color produced between ninhydrin and a-amino acids are examples of reactions discussed previously in the context of carbonyl chemistry (see, for instance, Section 16-4C). Write mechanisms, based insofar as possible on analogy, for each of the steps involved in the ninhydrin test, using glycine as an example. Would you expect ammonia or methanamine to give the blue color Explain. 

Exercise 25-14 Show how the following amino acids may be prepared from the indicated method and starting materials ... 

Exercise 25-18 The tripeptide, eisenine, has only one free carboxyl group, does not react with 2,4-dinitrofluorobenzene, and on complete hydrolysis yields 2 moles of L-glutamic acid, 1 mole of L-alanine, and 1 mole of ammonia. Alanine is indicated to be the C-terminal amino acid. Write a structure for eisenine that is in accord with the above facts. 

Exercise 25-20 A hexapeptide was subjected to the transformations diagrammed below. (The commas between the amino acids indicate the sequence is unknown or unspecified.) Deduce the structure of the hexapeptide. 

Exercise 25-21 How could an optically pure W-acylamino acid racemize and lead to racemic W-acylpeptides as the result of a peptide coupling reaction wherein the carboxyl group of the amino acid was converted to an anhydride group (Review Section 25-5A.)... 

Exercise 25-25 Indicate the steps that would be necessary to attach each of the amino acids listed to the A/-terminus of a peptide chain. Assume that any side-chain functions in the peptide are suitably protected, but do not assume that the amino acids will couple with the peptide without suitable protection of their functional groups, a. lysine b. aspartic acid c. cystine d. serine... 

Exercise 25-26 Show how each of the following substances may be synthesized starting with the individual amino acids. Indicate the reagents needed in each step, a. glutamylglycine (Glu-Gly) b. Tyr-Ala-Va ... 

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