TABLE 3-1 Properties and Conventions Associated with the Common Amino Acids Foun
ID: 573468 • Letter: T
Question
TABLE 3-1 Properties and Conventions Associated with the Common Amino Acids Found in Proteins pKa values Hydropa- th pK2 (-NHJ) pKR (R group) Amino Abb revia- Occurrence in acid tion/symbol Mra0C00H) Nonpolar, aliphatic R groups pl indexb proteins (%)" Glycine Alanine Proline Valine Leucine Isoleucine Methion- ine 75 2.34 89 2.34 115 1.99 117 2.32 131 2.36 1312.36 Met M 149 2.28 9.60 9.69 10.96 9.62 9.60 9.68 9.21 5.97 6.01 6.48 5.97 5.98 6.02 5.74 Ala A Pro P Val V 4.5 Aromatic R groups Phenyl- alanine Tyrosine Trypto- 165 1.83 5.48 10.07 5.66 5.89 Tyr Y1812.20 Trp W2042.38 9.39 an Polar, uncharged R groups Serine Threonine Cysteinee Asparagine Asn N Glutamine Positively charged R groups Lysine Histidine Arginine Negatively charged R groups Aspartate Glutamate Ser S Thr T 1052.21 1192.11 21 1.96 132 2.02 146 2.17 5.68 5.87 8.185.07 -0.8 9.62 10.28 8.80 Gln Q 5.65 8.95 1462.18 1551.82 Arg R174 2.17 10.539.74 6.00 7.59 12.4810.76 Lys K 1S 9.04 133 1.88 147 2.19 9.60 9.67 3.65 2.77 4.25 3.22 Sp Glu EExplanation / Answer
Polypeptide - RVKDS
Looking at the pKa values
beyond pH 9.0 and below pH 10.53, charges on,
R = +1
V = 0
K = +1
D = -1
S = -1
So net charge would be zero
The pI of polypetide is thus = 1/2(9.0 + 10.53) = 9.765
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