Properties and Conventions Associated with the standard Amino acids pk. values abreviated K Hydropathy Occurrence nane COOH (-NHi) (R group? in proteins (%) Nonpolar aliphatic R GroupS Glyc ine Gly G 75 2.34 9.60 5.97 D.4 7.2 Alanine Ala A 9.69 valine Val V 117 2.32 9.62 5.97 4.2 6.6 Leucine Leu 131 2,36 9,60 59 38 9.1 isoleucine 2.36 Methionine Met M 149 2.28 921 5.74 L 9 2.3 Aromatic R groups Phenylalanine Phe F 165 1.83 9.13 28 3.9 lyr Y 9.11 10.07 3.2 204 2.38 9,39 Polar, uncharged R groups Serine Ser s 105 2.21 9,15 5.68 -0.8 6.8 Proline Pro P 115 199 1096 648 1.6 Threonine Th T 119 2.11 9.62 587 0.7 5.9 Cysteine Cys C 196 10,28 8.18 Asparagine Asn N 132 202 880 541 3.5 4.3 Glutamine GIn c 146 2.17 9.13 565 3.5 4.2 Positively charged R groups ysine 2.18 89 Histidine 155 1.82 9.17 6.D 759 Arginine Arg R 174 2.17 9.04 12.48 1D.76 6.1 Negatively charged R Groups aspartate A 133 9.60 3.65 2.77 3.5 6.3 Glutamate Glu E 14了 2.19 9.67 41.25 322 3.5 6.3 A scale combining hydrophobicity and hydro phil icity of R groups; it can be used to measure the tendency of an amino acid to seek an aqueous environment < values) or a hydrophobic environment(+ values). see Chapter 12. From Kyte, J& Doolittle, R F (1982)J, Mol. 6io.157,105-132. Structure and the PrincipLes of Protein Conformation( Fasman, G.D., ed) Plenum Press, NY, pp. 599-527. In Prediction of Protein 'Average occurrence in over 1150 proteins From Doolittle, R.F.(1989)Redu ndancies in protein sequence