Finding intermodel H-bonds Finding intramodel H-bonds Constraints relaxed by 0.4 angstroms and 20 degrees Models used: #0 8rqw_A.cif H-bonds (donor, acceptor, hydrogen, D..A dist, D-H..A dist): ALA 4.A N GLN 5.A O no hydrogen 2.854 N/A PHE 7.A N ALA 2.A O no hydrogen 2.951 N/A ASP 8.A N TYR 90.A OH no hydrogen 3.028 N/A ARG 12.A NH1 ASP 32.A OD1 no hydrogen 3.085 N/A TYR 13.A N VAL 9.A O no hydrogen 3.440 N/A TYR 13.A OH ASP 76.A OD2 no hydrogen 2.696 N/A THR 14.A N TYR 31.A O no hydrogen 2.922 N/A SER 17.A N SER 29.A O no hydrogen 2.986 N/A TYR 18.A OH GLU 21.A OE1 no hydrogen 3.216 N/A ILE 19.A N VAL 27.A O no hydrogen 3.021 N/A GLY 22.A N GLY 25.A O no hydrogen 2.599 N/A VAL 27.A N GLY 20.A O no hydrogen 2.932 N/A CYS 28.A N ILE 41.A O no hydrogen 2.807 N/A SER 29.A N SER 17.A O no hydrogen 3.017 N/A SER 29.A OG SER 17.A O no hydrogen 3.420 N/A ALA 30.A N VAL 39.A O no hydrogen 2.865 N/A TYR 31.A N THR 14.A O no hydrogen 2.716 N/A ASP 32.A N VAL 37.A O no hydrogen 3.063 N/A ASN 33.A N ARG 12.A O no hydrogen 2.765 N/A ASN 33.A ND2 PRO 11.A O no hydrogen 3.344 N/A ASN 33.A ND2 ARG 12.A O no hydrogen 2.769 N/A ASN 33.A ND2 THR 14.A OG1 no hydrogen 2.736 N/A LEU 34.A N ASP 32.A OD1 no hydrogen 2.920 N/A ASN 35.A N ASP 32.A OD1 no hydrogen 2.844 N/A LYS 36.A N ASP 32.A O no hydrogen 2.708 N/A ARG 38.A NH1 ASN 15.A O no hydrogen 3.035 N/A ARG 38.A NH2 ASN 15.A O no hydrogen 2.866 N/A ARG 38.A NH2 SER 29.A OG no hydrogen 2.649 N/A VAL 39.A N ALA 30.A O no hydrogen 2.767 N/A ALA 40.A N GLN 93.A O no hydrogen 2.982 N/A ILE 41.A N CYS 28.A O no hydrogen 2.643 N/A LYS 42.A N ILE 91.A O no hydrogen 2.943 N/A LYS 43.A N MET 26.A O no hydrogen 2.987 N/A LYS 43.A NZ VAL 6.A O no hydrogen 2.240 N/A ILE 44.A N VAL 89.A O no hydrogen 2.783 N/A SER 45.A N TYR 24.A O no hydrogen 2.699 N/A SER 45.A OG ASP 88.A OD1 no hydrogen 2.714 N/A HIS 49.A N PRO 46.A O no hydrogen 3.324 N/A CYS 53.A N HIS 49.A O no hydrogen 3.068 N/A CYS 53.A SG PRO 46.A O no hydrogen 3.158 N/A CYS 53.A SG HIS 49.A O no hydrogen 3.475 N/A GLN 54.A N GLN 50.A O no hydrogen 2.988 N/A ARG 55.A N THR 51.A O no hydrogen 3.102 N/A THR 56.A N TYR 52.A O no hydrogen 3.048 N/A THR 56.A OG1 TYR 52.A O no hydrogen 2.674 N/A LEU 57.A N CYS 53.A O no hydrogen 2.924 N/A ARG 58.A N GLN 54.A O no hydrogen 2.993 N/A GLU 59.A N ARG 55.A O no hydrogen 3.021 N/A ILE 60.A N THR 56.A O no hydrogen 3.005 N/A LYS 61.A N LEU 57.A O no hydrogen 2.908 N/A ILE 62.A N ARG 58.A O no hydrogen 2.971 N/A LEU 63.A N GLU 59.A O no hydrogen 2.927 N/A LEU 64.A N ILE 60.A O no hydrogen 3.032 N/A ARG 65.A N LYS 61.A O no hydrogen 3.227 N/A ARG 65.A N ILE 62.A O no hydrogen 2.988 N/A ARG 65.A NE ALA 315.A O no hydrogen 3.095 N/A ARG 65.A NH2 ALA 315.A O no hydrogen 3.317 N/A ARG 65.A NH2 PRO 316.A O no hydrogen 3.147 N/A PHE 66.A N ILE 62.A O no hydrogen 2.899 N/A ARG 67.A N TYR 127.A OH no hydrogen 3.015 N/A ASN 70.A ND2 LEU 151.A O no hydrogen 3.021 N/A ILE 71.A N HIS 68.A O no hydrogen 3.119 N/A ILE 72.A N ILE 153.A O no hydrogen 2.987 N/A ASN 75.A N VAL 92.A O no hydrogen 2.763 N/A ASP 76.A N VAL 92.A O no hydrogen 3.371 N/A ILE 78.A N TYR 90.A O no hydrogen 2.856 N/A ARG 79.A NE ALA 80.A O no hydrogen 3.070 N/A ARG 79.A NH2 ALA 80.A O no hydrogen 2.933 N/A THR 82.A OG1 GLN 85.A OE1 no hydrogen 2.643 N/A GLU 84.A N GLU 84.A OE1 no hydrogen 2.694 N/A GLN 85.A N THR 82.A O no hydrogen 3.236 N/A GLN 85.A N THR 82.A OG1 no hydrogen 3.232 N/A MET 86.A N ILE 83.A O no hydrogen 3.095 N/A VAL 89.A N ILE 44.A O no hydrogen 2.829 N/A TYR 90.A N ILE 78.A O no hydrogen 2.808 N/A ILE 91.A N LYS 42.A O no hydrogen 2.857 N/A VAL 92.A N ASP 76.A O no hydrogen 2.817 N/A GLN 93.A N ALA 40.A O no hydrogen 2.985 N/A THR 98.A N LEU 145.A O no hydrogen 2.905 N/A THR 98.A OG1 ASP 99.A O no hydrogen 3.275 N/A ASP 99.A N THR 98.A OG1 no hydrogen 2.669 N/A LEU 100.A N LEU 143.A O no hydrogen 2.969 N/A LYS 102.A N ASP 99.A OD1 no hydrogen 3.004 N/A LYS 102.A NZ ASP 99.A OD2 no hydrogen 3.391 N/A LEU 103.A N ASP 99.A O no hydrogen 2.967 N/A LEU 104.A N LEU 100.A O no hydrogen 2.848 N/A LYS 105.A N TYR 101.A O no hydrogen 3.148 N/A THR 106.A N LEU 103.A O no hydrogen 3.164 N/A THR 106.A OG1 LYS 102.A O no hydrogen 3.144 N/A THR 106.A OG1 LEU 103.A O no hydrogen 3.420 N/A GLN 107.A N LEU 103.A O no hydrogen 2.818 N/A SER 110.A OG HIS 113.A ND1 no hydrogen 2.622 N/A HIS 113.A N SER 110.A OG no hydrogen 3.056 N/A HIS 113.A ND1 SER 110.A OG no hydrogen 2.622 N/A ILE 114.A N SER 110.A O no hydrogen 3.073 N/A CYS 115.A N ASN 111.A O no hydrogen 3.018 N/A CYS 115.A SG TYR 300.A O no hydrogen 3.163 N/A TYR 116.A N ASP 112.A O no hydrogen 3.064 N/A PHE 117.A N HIS 113.A O no hydrogen 2.849 N/A LEU 118.A N ILE 114.A O no hydrogen 2.927 N/A TYR 119.A N CYS 115.A O no hydrogen 2.923 N/A TYR 119.A OH GLU 310.A OE2 no hydrogen 2.668 N/A GLN 120.A N TYR 116.A O no hydrogen 3.077 N/A GLN 120.A NE2 TYR 116.A O no hydrogen 3.426 N/A GLN 120.A NE2 CYS 149.A O no hydrogen 2.998 N/A ILE 121.A N PHE 117.A O no hydrogen 2.884 N/A LEU 122.A N LEU 118.A O no hydrogen 2.961 N/A ARG 123.A N TYR 119.A O no hydrogen 2.857 N/A ARG 123.A NE ASP 309.A O no hydrogen 2.853 N/A ARG 123.A NH1 GLU 69.A OE1 no hydrogen 2.996 N/A ARG 123.A NH1 ASN 70.A OD1 no hydrogen 2.862 N/A ARG 123.A NH2 GLU 69.A OE1 no hydrogen 3.355 N/A ARG 123.A NH2 ASP 309.A O no hydrogen 2.891 N/A GLY 124.A N GLN 120.A O no hydrogen 3.030 N/A LEU 125.A N ILE 121.A O no hydrogen 2.844 N/A LYS 126.A N LEU 122.A O no hydrogen 2.755 N/A LYS 126.A NZ GLU 310.A O no hydrogen 2.825 N/A TYR 127.A N ARG 123.A O no hydrogen 3.461 N/A ILE 128.A N GLY 124.A O no hydrogen 3.099 N/A HIS 129.A N LEU 125.A O no hydrogen 2.893 N/A HIS 129.A NE2 ASP 198.A OD2 no hydrogen 2.715 N/A SER 130.A N LYS 126.A O no hydrogen 2.901 N/A SER 130.A OG TYR 127.A O no hydrogen 2.581 N/A ALA 131.A N TYR 127.A O no hydrogen 3.111 N/A ALA 131.A N ILE 128.A O no hydrogen 3.018 N/A ASN 132.A N HIS 129.A O no hydrogen 2.956 N/A ASN 132.A ND2 PHE 317.A O no hydrogen 3.376 N/A VAL 133.A N ILE 128.A O no hydrogen 3.254 N/A LEU 134.A N ARG 160.A O no hydrogen 2.837 N/A HIS 135.A N ASP 198.A OD2 no hydrogen 2.969 N/A HIS 135.A NE2 CYS 154.A O no hydrogen 2.909 N/A ARG 136.A N ASP 198.A OD1 no hydrogen 2.897 N/A ARG 136.A NE GLY 192.A O no hydrogen 2.993 N/A ARG 136.A NH1 LEU 158.A O no hydrogen 2.775 N/A ARG 136.A NH2 LYS 191.A O no hydrogen 3.317 N/A ASP 137.A N HIS 135.A ND1 no hydrogen 2.995 N/A LYS 139.A NZ ASP 137.A OD1 no hydrogen 3.415 N/A LYS 139.A NZ ASP 137.A OD2 no hydrogen 2.957 N/A ASN 142.A N LYS 139.A O no hydrogen 2.937 N/A ASN 142.A ND2 ASP 155.A OD2 no hydrogen 3.082 N/A LEU 143.A N PRO 140.A O no hydrogen 3.091 N/A LEU 144.A N LYS 152.A O no hydrogen 2.878 N/A LEU 145.A N THR 98.A O no hydrogen 2.977 N/A ASN 146.A N ASP 150.A O no hydrogen 3.274 N/A ASN 146.A ND2 ASP 150.A OD2 no hydrogen 2.942 N/A THR 148.A N ASN 146.A OD1 no hydrogen 3.169 N/A THR 148.A OG1 ASN 146.A OD1 no hydrogen 3.191 N/A THR 148.A OG1 ASP 150.A OD2 no hydrogen 2.810 N/A CYS 149.A N ASN 146.A O no hydrogen 3.086 N/A ASP 150.A N ASN 146.A OD1 no hydrogen 2.946 N/A LEU 151.A N GLN 120.A OE1 no hydrogen 2.883 N/A LYS 152.A N LEU 144.A O no hydrogen 2.913 N/A LYS 152.A NZ GLU 69.A O no hydrogen 2.750 N/A ILE 153.A N ASN 70.A O no hydrogen 2.737 N/A CYS 154.A N ASN 142.A O no hydrogen 3.001 N/A PHE 156.A N GLU 59.A OE2 no hydrogen 3.103 N/A GLY 157.A N ASP 155.A OD1 no hydrogen 3.454 N/A ALA 159.A N PHE 156.A O no hydrogen 3.173 N/A ARG 160.A N LEU 134.A O no hydrogen 3.017 N/A ARG 160.A NH1 ALA 159.A O no hydrogen 3.339 N/A ALA 162.A N ASN 132.A O no hydrogen 2.806 N/A ASP 163.A N TYR 193.A O no hydrogen 2.862 N/A HIS 166.A N ASP 163.A O no hydrogen 3.130 N/A HIS 166.A ND1 ASP 163.A OD1 no hydrogen 3.017 N/A ASP 167.A N PRO 164.A O no hydrogen 3.401 N/A THR 169.A N ASN 189.A O no hydrogen 2.914 N/A GLY 170.A N THR 169.A OG1 no hydrogen 2.825 N/A LEU 172.A N MET 187.A O no hydrogen 3.005 N/A THR 173.A OG1 GLY 170.A O no hydrogen 2.940 N/A GLU 178.A N ASP 137.A OD1 no hydrogen 3.406 N/A ARG 179.A NH1 GLY 218.A O no hydrogen 3.259 N/A TRP 180.A N GLU 178.A OE2 no hydrogen 3.302 N/A TRP 180.A NE1 GLY 218.A O no hydrogen 2.939 N/A TYR 181.A N GLU 178.A O no hydrogen 3.155 N/A TYR 181.A OH GLU 208.A OE1 no hydrogen 2.610 N/A ARG 182.A N ARG 179.A O no hydrogen 3.166 N/A ARG 182.A NE ALA 177.A O no hydrogen 2.913 N/A ARG 182.A NH2 ALA 177.A O no hydrogen 2.810 N/A GLU 185.A N GLU 185.A OE1 no hydrogen 2.837 N/A ILE 186.A N ALA 183.A O no hydrogen 3.037 N/A MET 187.A N PRO 184.A O no hydrogen 3.055 N/A LEU 188.A N GLU 185.A O no hydrogen 2.938 N/A ASN 189.A N GLU 185.A O no hydrogen 2.779 N/A SER 190.A N GLU 185.A O no hydrogen 2.944 N/A SER 190.A OG ASP 167.A OD1 no hydrogen 2.943 N/A SER 190.A OG ASP 167.A OD2 no hydrogen 2.819 N/A LYS 191.A N ASP 167.A O no hydrogen 2.805 N/A GLY 192.A N SER 190.A OG no hydrogen 2.980 N/A TYR 193.A N ASP 167.A OD1 no hydrogen 2.865 N/A THR 194.A OG1 SER 196.A OG no hydrogen 3.030 N/A LYS 195.A NZ HIS 129.A O no hydrogen 2.937 N/A SER 196.A OG THR 194.A OG1 no hydrogen 3.030 N/A ILE 197.A N THR 194.A O no hydrogen 3.126 N/A ASP 198.A N LYS 195.A O no hydrogen 3.020 N/A TRP 200.A N SER 196.A O no hydrogen 3.185 N/A SER 201.A N ILE 197.A O no hydrogen 3.388 N/A SER 201.A OG TYR 181.A O no hydrogen 2.824 N/A SER 201.A OG ILE 197.A O no hydrogen 3.308 N/A VAL 202.A N ASP 198.A O no hydrogen 2.973 N/A GLY 203.A N ILE 199.A O no hydrogen 2.936 N/A CYS 204.A N TRP 200.A O no hydrogen 2.976 N/A CYS 204.A SG TRP 180.A O no hydrogen 3.881 N/A CYS 204.A SG TRP 200.A O no hydrogen 3.529 N/A ILE 205.A N SER 201.A O no hydrogen 2.983 N/A LEU 206.A N VAL 202.A O no hydrogen 2.839 N/A ALA 207.A N GLY 203.A O no hydrogen 2.958 N/A GLU 208.A N CYS 204.A O no hydrogen 3.092 N/A MET 209.A N ILE 205.A O no hydrogen 2.865 N/A LEU 210.A N LEU 206.A O no hydrogen 3.070 N/A SER 211.A N GLU 208.A O no hydrogen 3.423 N/A SER 211.A OG ALA 207.A O no hydrogen 3.192 N/A SER 211.A OG ARG 213.A O no hydrogen 3.044 N/A ASN 212.A N GLU 208.A O no hydrogen 2.747 N/A ASN 212.A ND2 LEU 104.A O no hydrogen 2.794 N/A ASN 212.A ND2 GLN 107.A O no hydrogen 2.754 N/A ARG 213.A N SER 211.A OG no hydrogen 3.115 N/A GLY 218.A N PHE 216.A O no hydrogen 3.010 N/A GLY 218.A N GLN 224.A OE1 no hydrogen 3.120 N/A LYS 219.A N ASP 223.A OD2 no hydrogen 2.812 N/A TYR 221.A OH THR 173.A O no hydrogen 2.645 N/A GLN 224.A N HIS 220.A O no hydrogen 3.053 N/A GLN 224.A NE2 PHE 216.A O no hydrogen 2.822 N/A LEU 225.A N LEU 222.A O no hydrogen 3.197 N/A ASN 226.A N LEU 222.A O no hydrogen 3.404 N/A HIS 227.A N ASP 223.A O no hydrogen 3.069 N/A HIS 227.A ND1 ASP 223.A O no hydrogen 3.219 N/A ILE 228.A N GLN 224.A O no hydrogen 3.088 N/A LEU 229.A N LEU 225.A O no hydrogen 2.899 N/A GLY 230.A N ASN 226.A O no hydrogen 2.891 N/A ILE 231.A N ILE 228.A O no hydrogen 3.119 N/A LEU 232.A N ILE 228.A O no hydrogen 2.942 N/A GLY 233.A N LEU 229.A O no hydrogen 2.767 N/A SER 234.A N LYS 258.A O no hydrogen 2.763 N/A SER 234.A OG LYS 258.A O no hydrogen 3.285 N/A ASP 239.A N SER 236.A OG no hydrogen 3.083 N/A LEU 240.A N SER 236.A O no hydrogen 2.874 N/A ASN 241.A N GLN 237.A O no hydrogen 2.842 N/A CYS 242.A N GLU 238.A O no hydrogen 3.331 N/A ILE 243.A N LEU 240.A O no hydrogen 2.820 N/A ARG 249.A N ASN 245.A O no hydrogen 3.045 N/A ASN 250.A N LEU 246.A O no hydrogen 2.936 N/A TYR 251.A N LYS 247.A O no hydrogen 3.007 N/A LEU 252.A N ALA 248.A O no hydrogen 3.076 N/A LEU 253.A N ARG 249.A O no hydrogen 2.938 N/A SER 254.A N ASN 250.A O no hydrogen 3.000 N/A SER 254.A N TYR 251.A O no hydrogen 3.056 N/A SER 254.A OG TYR 251.A O no hydrogen 2.708 N/A LEU 255.A N LEU 252.A O no hydrogen 3.249 N/A LYS 258.A N SER 234.A OG no hydrogen 2.774 N/A LYS 258.A NZ PRO 256.A O no hydrogen 2.684 N/A LYS 260.A NZ ASP 279.A OD1 no hydrogen 3.322 N/A VAL 261.A N ILE 231.A O no hydrogen 2.789 N/A TRP 263.A NE1 ASP 279.A OD1 no hydrogen 3.115 N/A ARG 265.A N PRO 262.A O no hydrogen 2.854 N/A PHE 267.A N TRP 263.A O no hydrogen 2.839 N/A ALA 270.A N PHE 267.A O no hydrogen 3.101 N/A LYS 273.A N ASP 271.A OD1 no hydrogen 2.820 N/A LYS 273.A NZ GLU 302.A OE2 no hydrogen 2.887 N/A LEU 275.A N ASP 271.A O no hydrogen 3.205 N/A ASP 276.A N SER 272.A O no hydrogen 3.042 N/A LEU 277.A N LYS 273.A O no hydrogen 3.096 N/A LEU 278.A N ALA 274.A O no hydrogen 2.856 N/A ASP 279.A N LEU 275.A O no hydrogen 3.049 N/A LYS 280.A N ASP 276.A O no hydrogen 3.302 N/A LYS 280.A N LEU 277.A O no hydrogen 2.996 N/A LYS 280.A NZ ASP 276.A OD1 no hydrogen 3.524 N/A LYS 280.A NZ ASP 276.A OD2 no hydrogen 3.247 N/A MET 281.A N LEU 277.A O no hydrogen 2.960 N/A LEU 282.A N LEU 278.A O no hydrogen 2.856 N/A THR 283.A OG1 ASP 279.A O no hydrogen 3.033 N/A THR 283.A OG1 LYS 280.A O no hydrogen 3.238 N/A ASN 285.A ND2 ASP 239.A OD1 no hydrogen 3.083 N/A HIS 287.A N ASN 285.A OD1 no hydrogen 2.967 N/A HIS 287.A ND1 ASN 285.A OD1 no hydrogen 3.128 N/A LYS 288.A N ASN 285.A O no hydrogen 3.046 N/A LYS 288.A NZ GLU 238.A OE2 no hydrogen 2.799 N/A LYS 288.A NZ ASP 239.A OD1 no hydrogen 2.771 N/A ARG 289.A N PRO 286.A O no hydrogen 3.357 N/A ARG 289.A NE THR 283.A O no hydrogen 2.960 N/A ARG 289.A NH1 GLU 185.A OE2 no hydrogen 2.810 N/A ARG 289.A NH1 SER 196.A O no hydrogen 2.883 N/A ARG 289.A NH2 GLU 185.A OE1 no hydrogen 2.875 N/A ARG 289.A NH2 GLU 185.A OE2 no hydrogen 3.475 N/A ARG 289.A NH2 THR 283.A O no hydrogen 2.980 N/A ARG 289.A NH2 PHE 284.A O no hydrogen 3.156 N/A ILE 290.A N LYS 280.A O no hydrogen 3.161 N/A GLU 291.A N GLN 294.A OE1 no hydrogen 2.917 N/A ALA 295.A N GLU 291.A O no hydrogen 2.940 N/A LEU 296.A N VAL 292.A O no hydrogen 3.061 N/A ALA 297.A N GLU 293.A O no hydrogen 3.399 N/A HIS 298.A N ALA 295.A O no hydrogen 3.060 N/A HIS 298.A NE2 ASP 276.A OD2 no hydrogen 2.757 N/A TYR 300.A N HIS 298.A ND1 no hydrogen 3.018 N/A LEU 301.A N HIS 298.A O no hydrogen 2.858 N/A GLU 302.A N PRO 299.A O no hydrogen 3.235 N/A TYR 304.A N LEU 301.A O no hydrogen 3.000 N/A TYR 305.A N LEU 301.A O no hydrogen 3.032 N/A ASP 306.A N GLU 310.A OE2 no hydrogen 2.888 N/A SER 308.A OG.A ASP 306.A OD1 no hydrogen 2.649 N/A ASP 309.A N ASP 306.A O no hydrogen 2.792 N/A GLU 310.A N PRO 307.A O no hydrogen 3.217 N/A ALA 313.A N SER 130.A OG no hydrogen 2.775 N/A PHE 317.A N ALA 131.A O no hydrogen 2.899 N/A MET 321.A N ASP 320.A OD1 no hydrogen 3.224 N/A LEU 323.A N MET 321.A O no hydrogen 2.713 N/A LEU 326.A N LEU 323.A O no hydrogen 3.356 N/A LYS 328.A NZ GLU 329.A OE2 no hydrogen 2.477 N/A LYS 330.A N PRO 327.A O no hydrogen 2.903 N/A LEU 331.A N PRO 327.A O no hydrogen 3.221 N/A LYS 332.A N LYS 328.A O no hydrogen 2.730 N/A LYS 332.A NZ ILE 83.A O no hydrogen 2.705 N/A LYS 332.A NZ MET 86.A O no hydrogen 2.625 N/A GLU 333.A N GLU 329.A O no hydrogen 3.184 N/A LEU 334.A N LYS 330.A O no hydrogen 2.959 N/A ILE 335.A N LEU 331.A O no hydrogen 2.863 N/A PHE 336.A N LYS 332.A O no hydrogen 2.841 N/A GLU 337.A N GLU 333.A O no hydrogen 3.018 N/A GLU 338.A N LEU 334.A O no hydrogen 2.856 N/A THR 339.A N ILE 335.A O no hydrogen 3.058 N/A THR 339.A N PHE 336.A O no hydrogen 3.254 N/A THR 339.A OG1 ILE 335.A O no hydrogen 2.796 N/A THR 339.A OG1 PHE 336.A O no hydrogen 3.038 N/A ALA 340.A N GLU 337.A O no hydrogen 3.325 N/A ARG 341.A NH2 GLU 338.A O no hydrogen 3.502 N/A PHE 342.A N THR 339.A O no hydrogen 3.318 N/A GLN 343.A N ALA 340.A O no hydrogen 2.966 N/A