Isoleucine formula

Without consulting chapter figures, draw Fischer projection formulas for glycine, aspartate, leucine, isoleucine, methionine, and threonine. 

The molecules of two organic compounds are sometimes composed of the same type and number of atoms, but arranged in different ways. The molecular formula of each one of such compounds, which are known as isomers (for example, isoleucine and alloisoleucine, shown in Fig. 73), is therefore identical to that of the other only the structural formulas of the two isomers show the differences between their molecules (see Textbox 63). 

Isoleucine (He or I) ((25,35)-2-amino-3-methylpentanoic acid) is a nonpolar, neutral, aliphatic amino acid with the formula HOOCCH(NH2)CH(CH3)CH2CH3. Having a hydrocarbon side chain. He is classified as a hydrophobic amino acid. Together with Thr, He is one of the two common amino acids that have a chiral center. Although four stereoisomers of He are possible. He present in nature exists in only one enantiomeric form, that is, (25,35)-2-amino-3-methylpentanoic acid. ... 

Figure 2. Molecular Formulas of L-isoleucine, L-leucine, L-valine, and L-a-amino butyric acid...

Treatment The disease is treated with a synthetic formula that contains limited amounts of leucine, isoleucine, and valine—sufficient to provide the branched-chain amino acids necessary for normal growth and development without producing toxic levels. Infants suspected of having any form of MSUD should be tested within 24 hours of birth. Early diagnosis and treatment is essential if the child with MSUD is to develop normally. 

Maple syrup urine disease (MSUD) is a recessive disorder in which there is a partial or complete deficiency in branched-chain a-ketoacid dehydrogenase—an enzyme that decarboxylates leucine, isoleucine, and valine. These amino acids and their corresponding a-keto acids accumulate in the blood, causing a toxic effect that interferes with brain func tion. Symptoms include feeding problems, vomiting, dehydration, severe metabolic acidosis, and a characteristic smell of the urine. If untreated, the disease leads to mental retardation, physical disabilities, and death. Diagnosis is based on a blood sample within 24 hours of birth. Treatment of MSUD involves a synthetic formula that contains limited amounts of leucine, isoleucine, and valine. 

The amino acids in Table 27.1 that have more than one stereogenic center are isoleucine and threonine. The stereogenic centers are marked with an asterisk in the structural formulas shown. 

The eluate from the CM-Sephadex column is next dialyzed against distilled water at 4°C for 12-24 hours. A small quantity of protein is hydrolyzed in 6 A HCl for 72 hours at 100°C. After hydrolysis the acid is removed in a stream of filtered air and an appropriate aliquot of the hydrolyzate taken for analysis of isoleucine, leucine, and phenylalanine, an automatic amino acid analyzer being used. The percentage of Hb-F in the sample is calculated using this formula ... 

Amyl alcohols occur in eight isomeric forms and have the empirical formula CjHnOH. All are liquids at ambient conditions except 2,2-dimethylpropanol (neopentyl alcohol), which is a solid. Almost all amyl alcohols are manufactured in the United States by the hydroformylation of butylenes. Yeast fermentation processes for ethanol yield small amounts of 4-methyl-l-butanol (isoamyl alcohol) and 2-methyl-1-butanol (active amyl alcohol, scc-butyl-carbinol) as fusel oil. However, when the amino acids leucine and isoleucine are added to sugar fermentations by yeast, 87% and 80% yields of 4-methyl-l-butanol and 2-methyl-l-butanol, respectively, are obtained (Fieser and Fieser, 1950). These reactions are not suitable for commercial applications because of cost, but they do indicate the close structural relationship between these C5 amino acids and the C5 alcohols. The reactions occur under nitrogen-deficient conditions. If a nitrogen source is readily available, the production of the alcohols is lowered considerably. 

CONHa) 7 it was also reported that there was a single N-terminal threonine molecule. Although no detailed amino acid composition has been reported for the purified thyrocalcitonin prepared by Gudmunds-son et al. (G4), it differs considerably from the formula given above in that no cystine or isoleucine has been detected (Ml). 

This structure, although consistent with many facts, did not explain the peculiar properties of the A-terminal isoleucine and the negative test for —SH groups. Further experiments led to the conclusion that a thiazoline ring is formed between isoleucine and cysteine this was later proved to be correct. All these results led to the formula for bacitracin A which is now generally accepted - Figure 1.4). 

Leucine, (CH3)2CH.CH2.CHNH2.COOH, a-amino-isoca-proic acid, is found in a number of the organs of the body, and is obtained from proteins by hydrolysis. It has been synthesized from isovaleric aldehyde. Isoleucine, is an isomer of the formula CH3V... 

The methionine-, threonine-, vafine- and isoleucine-free infant formula XMTVl Analog is suitable for the... 

Figure 11 (continued) The 20 amino acids (a) the formulae and the symbols (three-letter and one-letter codes) that are used and (b) the absolute configurations of a general amino acid group and the side chains of threonine and isoleucine which contain asymmetric carbon atoms... 

Isoleucine and threonine both have two chiral centers. According to official nomenclature the names L-isoleucine and L-threonine both designate only one optically active diastereoisomer. The mirror images are named D-isoleucine and o-threonine, whereas the diastereoisomers are named l-and D-alloisoleucine and l- and D-allothreonine. The configurations of L-isoleucine and L-threonine are shown in the formulas in Table I. The table also contains notation of the configuration at the two centers according to the R,S system and according to traditional nomenclature for amino acids (lUPAC-IUB, 1975). 

The species H2Ar, HAl", andAl correspond to the forms H2B,HB andB of ordinary dibasic acids of the formula H2B. Certainly, there is also an equilibrium of intramolecular proton transfer, i.e., a tautomeric equilibrium HAl HAl. However, its equilibrium constant is so large that the concentration of HAl is very small. In ethanol-water mixtures as solvent, the respective equilibrium constants of glycine, L-alanine, L-valine, L-leucine, L-phenylalanine, L-isoleucine, L-methionine, and L-serine are aU between 10 and 10 [8]. 

Isoleucine contains two chiral carbon atoms. Draw the structural formula for isoleucine twice. In the first, identify one of the chiral carbons and circle the four groups attached to it. In the second, identify the other chiral carbon and circle the four groups attached to it. 

In the skeletal representations on the right, called a bond-line formula or carbon skeletal diagram, we assume that there is a carbon atom at every vertex and at the end of a line. Hydrogens attached to a vertex or to the end of a line are left out. When atoms that are neither carbon nor hydrogen, termed heteroatoms, are present, hydrogens attached to them are shown, as illustrated in the following examples. The second example is the amino acid isoleucine, which has the molecular formula C6H13NO2. 

Calculate valine and isoleucine intake provided by the infant formula/breast milk. Determine the amount of supplemental valine and isoleucine to add to meet recommended intakes (Table 16.1). The recommended concentration of valine and isoleucine supplanents is 10 mg/mL (1 g amino acid in 100 mL water). 

Recalculate the valine and isoleucine content provided by the infant formula or breast milk. 

Eight (8) day-old infant weighing 4 kg diagnosed with MSUD through newborn screening. This patient presents asymptomatically. Recent labs show plasma leucine concentration is 600 pmol/L, isoleucine is 80 pmol/L and valine is 180 pmol/L. The infant is currently taking 23 oz of Enfamil Premium powdered formula... 

Rounded to nearest whole number for amount of formula powders, leucine, isoleucine, valine, and energy and to the nearest 0.1 g for protein Nutricia North America (Rockville, MD)... 

Nutrient goal/kg x Infant weight=daily requirement Leucine 90 mg/kg x 4 kg=360 mg/day Isoleucine 50 mg/kg x 4 kg=200 mg Valine 50 mg/kg x 4 kg=200 mg Protein 3.0 g proteinx4 kg=12 g total protein requirement Energy 110-120 kcal/kgx4kg=440-480kcal/kg Step 2 Calculate amount of standard infant formula needed to meet daily LEU requirement. 

X 100=66 g BCAA-free medical food required in the diet prescription Step 6 Calculate amount of isoleucine and valine provided from standard infant formula (note there is no LEU, ILE, or VAL in BCAA-free medical food)... 

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