3.1 Amino Acids 77 TABLE 3-1P Properties and Conventions Associated with the Com

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3.1 Amino Acids 77 TABLE 3-1P Properties and Conventions Associated with the Common Amino Acids Found in Proteins pk, values Abbreviation/ Hydropathy -index Amino acid Nonpolar, aliphatic R groups Glycine Alanine symbol Occurrence in proteins M," (-COOH) (-NH?) (Rgroup) -pl (%) Ala A Pro P Val V Leu L 75 2.34 9.60 89 234 9.69 115 1.99 10.96 5.97-0.4 6.01 6.48 -1.6 5.97 4.2 117 2.32 962 131 236 9.60 131 236 9.68 149 228 921 Valine 6.6 5.98 8.02 5.741.9 5.3 2.3 Methionine Met M Aromatie R groups Phenylalanine Phe F Tyrosine Tyr Y Tryptophan Trp 204 2.38 9.39 Polar, uncharged R groups 165 1.83 181 2.20 9.11 10.07 5.66 1.3 5.48 3.2 -0.9 105 221 9.15 5.68 -0.8 5.87-0.7 Cysteine Cys C 121 196 10.28 8.18 5.07 2.5 5.41 -3.5 5.65-3.5 Ser S Thr T 6.8 Asn N Gin Q 132 2.02 8.80 146 2.17 9.13 Asparagine 4.2 Positively charged R groups 146 2.18 8.95 10.53 9.74 -3.9 Lys K His H 155 1.82 9.17 6.00 7.59 32 Arg R Histidine 2.3 174 2.17 904 12.48 10.76 45 Negatively charged R groups 133 1.88 9.60 3652.77-3.5 147 5.3 6.3 Glu E , salves reflect the structares as shown in Figure 3-5 The elements of water(,18)a scale combiing hydrophobicity and deleted when the anino acid is incorporated into a polgpeptide hydrophilicity of R groups se values neflect the free energy(&G;) of transfer of the amina acid side chain from a hydrophoblic solvest to waerThi aniso acid side chaies, and unfavorable (3pesitive value in the index) for amino acids with nonpolar or dites and S favorable (A6?0; segative value in the index) for chrged or polar From Kune, 1.&Doclile;, R..(1982) A simple method for displaging the hydroparhic character of a protein.&Mol; Bvel 157, 105-132 Pronrie Structare and the Principles of Protein Conformation ccumence in more than 1,150 proteins. From Doolittle, R.F.(1989) Redundancies in pratein sequences, in Prediction f Pamas, G.D, ed.p599-623, Pium Pres, New York pteneis geneally classified as polar despite having a positive hydropathy indes. This reflects the abelity of the sulthydnyl group to act as a weak acid and to form a weak hydrogen bend with e or nitrogen mercallnd nantiomers confusing. The additional carbons in an R group are

Explanation / Answer

Answer.

The value of pKa increases whenever there is decrease in acidity.

The positive inductive effect and the negative inductive effect caused by ammonium and carboxylate ions cross each other, thus, also there is increase in the pKa value of the R chain.

The decrease in acidity is much in glutamate than aspartate, thus the values are as such.

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