Finding intermodel H-bonds Finding intramodel H-bonds Constraints relaxed by 0.4 angstroms and 20 degrees Models used: #0 4n93_A.cif H-bonds (donor, acceptor, hydrogen, D..A dist, D-H..A dist): GLN 6.A N SER 3.A OG no hydrogen 3.349 N/A ILE 7.A N SER 3.A O no hydrogen 2.979 N/A LEU 8.A N TRP 4.A O no hydrogen 2.833 N/A GLY 9.A N PRO 5.A O no hydrogen 2.980 N/A ARG 10.A N GLN 6.A O no hydrogen 3.060 N/A ARG 10.A NE ASP 16.A O no hydrogen 2.941 N/A ARG 10.A NH2 ASP 16.A O no hydrogen 3.436 N/A LEU 11.A N ILE 7.A O no hydrogen 3.070 N/A THR 12.A N LEU 8.A O no hydrogen 2.895 N/A THR 12.A OG1 LEU 8.A O no hydrogen 3.249 N/A THR 12.A OG1 GLY 9.A O no hydrogen 3.140 N/A ASP 13.A N GLY 9.A O no hydrogen 2.984 N/A ASN 14.A N LEU 11.A O no hydrogen 2.730 N/A ARG 15.A N ARG 10.A O no hydrogen 3.118 N/A LEU 17.A N GLU 55.A OE2 no hydrogen 2.842 N/A ALA 18.A N GLN 21.A OE1 no hydrogen 2.835 N/A GLY 20.A N GLU 58.A OE2 no hydrogen 2.761 N/A GLN 21.A N ALA 18.A O no hydrogen 3.146 N/A GLN 21.A NE2 GLN 6.A OE1 no hydrogen 3.163 N/A ALA 23.A N GLU 58.A OE1 no hydrogen 2.894 N/A TRP 24.A N GLY 20.A O no hydrogen 2.912 N/A ALA 25.A N GLN 21.A O no hydrogen 3.004 N/A MET 26.A N ALA 22.A O no hydrogen 2.873 N/A ASP 27.A N ALA 23.A O no hydrogen 2.867 N/A GLN 28.A N TRP 24.A O no hydrogen 3.024 N/A ILE 29.A N ALA 25.A O no hydrogen 3.051 N/A MET 30.A N MET 26.A O no hydrogen 2.842 N/A THR 31.A N ASP 27.A O no hydrogen 2.939 N/A THR 31.A OG1 ASP 27.A O no hydrogen 2.922 N/A THR 31.A OG1 GLN 28.A O no hydrogen 3.374 N/A THR 31.A OG1 ASN 33.A OD1 no hydrogen 2.873 N/A GLY 32.A N ILE 29.A O no hydrogen 3.462 N/A ASN 33.A N GLN 28.A O no hydrogen 2.916 N/A ARG 35.A N GLN 38.A OE1 no hydrogen 2.781 N/A ILE 39.A N ARG 35.A O no hydrogen 2.954 N/A ALA 40.A N PRO 36.A O no hydrogen 2.968 N/A ALA 41.A N ALA 37.A O no hydrogen 2.936 N/A PHE 42.A N GLN 38.A O no hydrogen 3.014 N/A ALA 43.A N ILE 39.A O no hydrogen 3.030 N/A VAL 44.A N ALA 40.A O no hydrogen 3.088 N/A ALA 45.A N ALA 41.A O no hydrogen 2.892 N/A MET 46.A N PHE 42.A O no hydrogen 2.819 N/A THR 47.A N ALA 43.A O no hydrogen 3.076 N/A THR 47.A OG1 ALA 43.A O no hydrogen 2.673 N/A MET 48.A N VAL 44.A O no hydrogen 2.925 N/A LYS 49.A N ALA 45.A O no hydrogen 2.971 N/A LYS 49.A NZ ASP 16.A OD1 no hydrogen 2.851 N/A LYS 49.A NZ ALA 50.A O no hydrogen 2.837 N/A LYS 49.A NZ GLU 55.A OE1 no hydrogen 2.815 N/A LYS 49.A NZ GLU 55.A OE2 no hydrogen 3.188 N/A ALA 50.A N MET 46.A O no hydrogen 3.000 N/A THR 52.A N GLU 55.A OE1 no hydrogen 3.008 N/A GLU 55.A N THR 52.A OG1 no hydrogen 3.228 N/A VAL 56.A N THR 52.A O no hydrogen 3.054 N/A GLY 57.A N ALA 53.A O no hydrogen 2.851 N/A GLU 58.A N ASP 54.A O no hydrogen 3.129 N/A LEU 59.A N GLU 55.A O no hydrogen 3.039 N/A ALA 60.A N VAL 56.A O no hydrogen 2.860 N/A GLY 61.A N GLY 57.A O no hydrogen 2.862 N/A VAL 62.A N GLU 58.A O no hydrogen 2.963 N/A MET 63.A N LEU 59.A O no hydrogen 2.964 N/A LEU 64.A N ALA 60.A O no hydrogen 2.786 N/A SER 65.A N GLY 61.A O no hydrogen 3.050 N/A SER 65.A OG VAL 62.A O no hydrogen 2.550 N/A HIS 66.A N MET 63.A O no hydrogen 3.036 N/A HIS 66.A NE2 ASP 27.A OD1 no hydrogen 2.789 N/A ALA 67.A N LEU 64.A O no hydrogen 2.974 N/A HIS 68.A N PHE 159.A O no hydrogen 3.017 N/A THR 74.A OG1 PRO 71.A O no hydrogen 2.577 N/A ALA 79.A N PRO 76.A O no hydrogen 3.204 N/A VAL 80.A N PRO 109.A O no hydrogen 3.004 N/A ASP 81.A N ALA 193.A O no hydrogen 3.036 N/A VAL 83.A N LEU 195.A O no hydrogen 3.176 N/A THR 85.A N GLY 197.A O no hydrogen 2.972 N/A THR 85.A OG1 GLY 86.A O no hydrogen 2.942 N/A GLY 86.A N ASP 228.A OD2 no hydrogen 2.794 N/A VAL 90.A N ASP 88.A OD1 no hydrogen 2.959 N/A THR 92.A OG1 VAL 93.A O no hydrogen 2.845 N/A VAL 93.A N LEU 266.A O no hydrogen 3.009 N/A ASN 94.A ND2 SER 122.A O no hydrogen 2.927 N/A SER 96.A OG GLU 229.A OE1 no hydrogen 2.694 N/A SER 96.A OG GLU 229.A OE2 no hydrogen 3.052 N/A MET 98.A N ASN 94.A O no hydrogen 3.123 N/A ALA 99.A N LEU 95.A O no hydrogen 2.900 N/A ALA 100.A N SER 96.A O no hydrogen 2.854 N/A ILE 101.A N THR 97.A O no hydrogen 3.264 N/A VAL 102.A N MET 98.A O no hydrogen 3.066 N/A VAL 103.A N ALA 99.A O no hydrogen 2.817 N/A ALA 104.A N ALA 100.A O no hydrogen 2.972 N/A ALA 105.A N ILE 101.A O no hydrogen 3.001 N/A ALA 106.A N VAL 102.A O no hydrogen 2.937 N/A ALA 106.A N VAL 103.A O no hydrogen 3.101 N/A GLY 107.A N ALA 104.A O no hydrogen 2.967 N/A VAL 108.A N VAL 103.A O no hydrogen 3.357 N/A VAL 110.A N GLY 150.A O no hydrogen 3.175 N/A VAL 111.A N VAL 80.A O no hydrogen 2.972 N/A LYS 112.A N GLY 152.A O no hydrogen 2.886 N/A LYS 112.A NZ VAL 82.A O no hydrogen 2.772 N/A LYS 112.A NZ HIS 113.A O no hydrogen 2.937 N/A HIS 113.A N ASP 81.A OD1 no hydrogen 3.318 N/A HIS 113.A ND1 GLY 183.A O no hydrogen 2.795 N/A GLY 114.A N CYS 154.A O no hydrogen 3.334 N/A ARG 116.A N ASN 115.A OD1 no hydrogen 2.929 N/A ARG 116.A NH1 ASP 126.A OD1 no hydrogen 3.094 N/A ARG 116.A NH1 GLU 129.A OE1 no hydrogen 2.746 N/A ARG 116.A NH2 GLU 129.A OE1 no hydrogen 3.453 N/A ARG 116.A NH2 GLU 129.A OE2 no hydrogen 3.330 N/A ALA 117.A N ASP 126.A OD2 no hydrogen 2.727 N/A LEU 121.A N ASN 91.A OD1 no hydrogen 3.140 N/A SER 122.A OG THR 127.A OG1 no hydrogen 3.060 N/A GLY 123.A N ASP 126.A OD2 no hydrogen 2.776 N/A ALA 125.A N ASN 115.A O no hydrogen 3.450 N/A THR 127.A N GLY 123.A O no hydrogen 3.058 N/A THR 127.A OG1 ASN 94.A OD1 no hydrogen 2.402 N/A THR 127.A OG1 SER 122.A OG no hydrogen 3.060 N/A THR 127.A OG1 GLY 123.A O no hydrogen 3.518 N/A LEU 128.A N GLY 124.A O no hydrogen 2.967 N/A GLU 129.A N ALA 125.A O no hydrogen 2.979 N/A ALA 130.A N ASP 126.A O no hydrogen 3.007 N/A LEU 131.A N THR 127.A O no hydrogen 2.930 N/A LEU 131.A N LEU 128.A O no hydrogen 3.093 N/A GLY 132.A N GLU 129.A O no hydrogen 2.959 N/A VAL 133.A N LEU 128.A O no hydrogen 2.997 N/A ARG 134.A NE ASP 136.A OD1 no hydrogen 2.985 N/A ARG 134.A NH1 GLY 343.A O no hydrogen 3.203 N/A ARG 134.A NH2 ASP 136.A OD1 no hydrogen 3.530 N/A ARG 134.A NH2 ASP 136.A OD2 no hydrogen 3.085 N/A VAL 142.A N GLY 138.A O no hydrogen 2.903 N/A ALA 143.A N PRO 139.A O no hydrogen 3.093 N/A ARG 144.A N ASP 140.A O no hydrogen 3.090 N/A ARG 144.A NE GLU 148.A OE2 no hydrogen 2.961 N/A ARG 144.A NH2 GLU 148.A OE1 no hydrogen 2.830 N/A ARG 144.A NH2 GLU 148.A OE2 no hydrogen 3.447 N/A SER 145.A N LEU 141.A O no hydrogen 2.872 N/A SER 145.A OG ILE 151.A O no hydrogen 2.660 N/A LEU 146.A N VAL 142.A O no hydrogen 2.949 N/A ALA 147.A N ALA 143.A O no hydrogen 2.995 N/A GLU 148.A N ARG 144.A O no hydrogen 2.776 N/A VAL 149.A N SER 145.A O no hydrogen 2.665 N/A GLY 150.A N LEU 146.A O no hydrogen 3.041 N/A GLY 152.A N VAL 110.A O no hydrogen 3.027 N/A CYS 154.A N LYS 112.A O no hydrogen 2.763 N/A ALA 156.A N GLY 114.A O no hydrogen 3.146 N/A ARG 158.A N PHE 155.A O no hydrogen 2.903 N/A ARG 158.A NH1 ARG 158.A O no hydrogen 3.151 N/A PHE 159.A N PHE 155.A O no hydrogen 3.199 N/A HIS 160.A N ALA 156.A O no hydrogen 2.827 N/A TYR 163.A N HIS 160.A O no hydrogen 3.093 N/A ARG 164.A N PRO 161.A O no hydrogen 3.253 N/A ARG 164.A NH1 PRO 161.A O no hydrogen 3.024 N/A ALA 167.A N TYR 163.A O no hydrogen 2.896 N/A ALA 168.A N ARG 164.A O no hydrogen 3.117 N/A VAL 169.A N HIS 165.A O no hydrogen 3.172 N/A ARG 170.A N ALA 166.A O no hydrogen 2.831 N/A ARG 171.A N ALA 167.A O no hydrogen 3.090 N/A GLU 172.A N ALA 168.A O no hydrogen 2.991 N/A ILE 173.A N VAL 169.A O no hydrogen 3.059 N/A GLY 174.A N ARG 170.A O no hydrogen 3.005 N/A VAL 175.A N ILE 173.A O no hydrogen 2.786 N/A VAL 178.A N THR 47.A OG1 no hydrogen 2.778 N/A PHE 179.A N THR 177.A OG1 no hydrogen 3.074 N/A ASN 180.A N THR 177.A O no hydrogen 2.980 N/A ASN 180.A ND2 THR 177.A O no hydrogen 3.328 N/A LEU 181.A N VAL 178.A O no hydrogen 3.083 N/A LEU 182.A N PHE 179.A O no hydrogen 3.010 N/A LEU 185.A N LEU 182.A O no hydrogen 3.054 N/A THR 186.A N GLY 183.A O no hydrogen 3.094 N/A THR 186.A OG1 LEU 182.A O no hydrogen 2.695 N/A THR 186.A OG1 GLY 183.A O no hydrogen 3.325 N/A ASN 187.A ND2 ASP 81.A OD2 no hydrogen 2.855 N/A ASN 187.A ND2 VAL 111.A O no hydrogen 2.921 N/A ALA 189.A N ASN 187.A OD1 no hydrogen 2.931 N/A ARG 190.A N ASN 187.A O no hydrogen 3.081 N/A ARG 192.A NE ARG 215.A O no hydrogen 3.443 N/A ARG 192.A NH1 ASP 77.A O no hydrogen 2.550 N/A ALA 193.A N ALA 79.A O no hydrogen 3.403 N/A GLY 194.A N SER 217.A O no hydrogen 3.163 N/A LEU 195.A N ASP 81.A O no hydrogen 2.964 N/A ILE 196.A N LEU 219.A O no hydrogen 2.840 N/A GLY 197.A N VAL 83.A O no hydrogen 2.919 N/A CYS 198.A N VAL 221.A O no hydrogen 2.922 N/A CYS 198.A SG PHE 200.A O no hydrogen 3.354 N/A ALA 199.A N THR 85.A OG1 no hydrogen 2.983 N/A ASP 202.A N ASP 202.A OD2.A no hydrogen 2.364 N/A LEU 203.A N PHE 200.A O no hydrogen 2.868 N/A ALA 204.A N PHE 200.A O no hydrogen 3.240 N/A MET 207.A N LEU 203.A O no hydrogen 2.995 N/A ALA 208.A N ALA 204.A O no hydrogen 2.856 N/A GLY 209.A N GLU 205.A O no hydrogen 2.829 N/A VAL 210.A N VAL 206.A O no hydrogen 3.054 N/A PHE 211.A N MET 207.A O no hydrogen 3.094 N/A ALA 212.A N ALA 208.A O no hydrogen 2.879 N/A ALA 213.A N GLY 209.A O no hydrogen 3.351 N/A ALA 213.A N VAL 210.A O no hydrogen 3.322 N/A ARG 214.A N PHE 211.A O no hydrogen 3.021 N/A ARG 214.A NH1 LEU 185.A O no hydrogen 3.009 N/A ARG 214.A NH2 LEU 185.A O no hydrogen 2.857 N/A SER 216.A OG ARG 192.A O no hydrogen 3.560 N/A SER 217.A N ARG 192.A O no hydrogen 2.819 N/A SER 217.A OG ALA 303.A O no hydrogen 2.627 N/A VAL 218.A N VAL 241.A O no hydrogen 2.851 N/A LEU 219.A N GLY 194.A O no hydrogen 3.013 N/A VAL 220.A N TRP 239.A O no hydrogen 2.974 N/A VAL 221.A N ILE 196.A O no hydrogen 2.871 N/A HIS 222.A N THR 237.A O no hydrogen 3.022 N/A HIS 222.A ND1 CYS 198.A O no hydrogen 2.758 N/A GLY 223.A N LEU 227.A O no hydrogen 2.937 N/A ASP 224.A N THR 235.A O no hydrogen 2.958 N/A GLY 226.A N GLY 223.A O no hydrogen 2.714 N/A LEU 227.A N ASP 225.A OD1 no hydrogen 3.257 N/A ASP 228.A N ASP 88.A OD2 no hydrogen 3.484 N/A LEU 230.A N ASN 296.A OD1 no hydrogen 2.894 N/A THR 231.A N SER 236.A OG no hydrogen 3.218 N/A THR 231.A OG1 ASP 225.A OD2 no hydrogen 2.633 N/A THR 231.A OG1 THR 233.A OG1 no hydrogen 3.309 N/A THR 233.A N THR 231.A OG1 no hydrogen 3.014 N/A THR 233.A OG1 ASP 225.A OD2 no hydrogen 2.483 N/A THR 233.A OG1 THR 231.A OG1 no hydrogen 3.309 N/A THR 235.A N THR 234.A OG1 no hydrogen 2.680 N/A THR 235.A OG1 ASP 224.A OD2 no hydrogen 2.537 N/A SER 236.A N PHE 251.A O no hydrogen 3.002 N/A THR 237.A N HIS 222.A O no hydrogen 2.786 N/A THR 237.A OG1 ASP 224.A OD1 no hydrogen 2.998 N/A ILE 238.A N LEU 249.A O no hydrogen 2.929 N/A TRP 239.A N VAL 220.A O no hydrogen 2.916 N/A TRP 239.A NE1 GLU 205.A OE2 no hydrogen 2.900 N/A ARG 240.A N ASP 247.A O no hydrogen 2.950 N/A ARG 240.A NH2 ASP 247.A OD2 no hydrogen 2.831 N/A VAL 241.A N VAL 218.A O no hydrogen 2.768 N/A ALA 242.A N SER 245.A O no hydrogen 2.999 N/A SER 245.A N ALA 242.A O no hydrogen 2.877 N/A SER 245.A OG ALA 242.A O no hydrogen 3.513 N/A ASP 247.A N ARG 240.A O no hydrogen 2.778 N/A LEU 249.A N ILE 238.A O no hydrogen 2.836 N/A PHE 251.A N SER 236.A O no hydrogen 2.894 N/A ALA 254.A N ASP 252.A OD1 no hydrogen 3.091 N/A GLY 255.A N ASP 252.A O no hydrogen 3.157 N/A PHE 256.A N PRO 253.A O no hydrogen 2.893 N/A GLY 257.A N ALA 254.A O no hydrogen 2.989 N/A PHE 258.A N PRO 253.A O no hydrogen 3.165 N/A ARG 260.A NH1 ASP 252.A OD1 no hydrogen 2.776 N/A ARG 260.A NH2 ASP 252.A OD1 no hydrogen 3.400 N/A ARG 260.A NH2 ASP 252.A OD2 no hydrogen 3.391 N/A ALA 261.A N THR 232.A O no hydrogen 3.050 N/A GLN 262.A N GLN 265.A OE1 no hydrogen 2.939 N/A GLN 262.A NE2 ALA 261.A O no hydrogen 3.614 N/A GLN 265.A N GLN 262.A O no hydrogen 2.854 N/A LEU 266.A N LEU 263.A O no hydrogen 2.896 N/A ALA 267.A N ASP 264.A O no hydrogen 3.305 N/A GLY 268.A N ASN 91.A O no hydrogen 2.888 N/A GLY 269.A N ASN 274.A OD1 no hydrogen 2.958 N/A ALA 273.A N ASP 270.A OD1 no hydrogen 2.872 N/A ASN 274.A N ASP 270.A O no hydrogen 2.765 N/A ASN 274.A ND2 THR 92.A O no hydrogen 3.693 N/A ASN 274.A ND2 ASN 94.A OD1 no hydrogen 2.870 N/A ALA 275.A N ALA 271.A O no hydrogen 2.812 N/A ALA 276.A N GLN 272.A O no hydrogen 3.047 N/A ALA 277.A N ALA 273.A O no hydrogen 3.042 N/A VAL 278.A N ASN 274.A O no hydrogen 3.143 N/A ARG 279.A N ALA 275.A O no hydrogen 3.095 N/A ARG 279.A NH2.B LEU 131.A O no hydrogen 3.143 N/A ALA 280.A N ALA 276.A O no hydrogen 3.008 N/A VAL 281.A N ALA 277.A O no hydrogen 3.136 N/A LEU 282.A N VAL 278.A O no hydrogen 2.931 N/A GLY 283.A N ARG 279.A O no hydrogen 2.951 N/A GLY 284.A N VAL 281.A O no hydrogen 3.078 N/A ALA 285.A N ALA 280.A O no hydrogen 3.066 N/A ARG 290.A NH1 ASP 328.A OD1 no hydrogen 2.952 N/A ARG 290.A NH2 ASP 328.A OD1 no hydrogen 2.964 N/A ARG 290.A NH2 ASP 328.A OD2 no hydrogen 3.313 N/A ASP 291.A N GLY 287.A O no hydrogen 3.072 N/A ALA 292.A N PRO 288.A O no hydrogen 3.076 N/A VAL 293.A N VAL 289.A O no hydrogen 2.984 N/A VAL 294.A N ARG 290.A O no hydrogen 2.801 N/A LEU 295.A N ASP 291.A O no hydrogen 2.958 N/A ASN 296.A N ALA 292.A O no hydrogen 3.131 N/A ASN 296.A ND2 LEU 230.A O no hydrogen 2.999 N/A ASN 296.A ND2 ALA 292.A O no hydrogen 2.764 N/A ALA 297.A N VAL 293.A O no hydrogen 2.848 N/A ALA 298.A N VAL 294.A O no hydrogen 2.916 N/A GLY 299.A N LEU 295.A O no hydrogen 3.064 N/A ALA 300.A N ASN 296.A O no hydrogen 3.113 N/A ILE 301.A N ALA 297.A O no hydrogen 3.045 N/A VAL 302.A N ALA 298.A O no hydrogen 2.726 N/A ALA 303.A N GLY 299.A O no hydrogen 2.946 N/A HIS 304.A N ALA 300.A O no hydrogen 2.953 N/A HIS 304.A NE2 ASP 78.A OD2 no hydrogen 2.777 N/A ALA 305.A N ILE 301.A O no hydrogen 2.952 N/A GLY 306.A N VAL 302.A O no hydrogen 3.109 N/A LEU 307.A N HIS 304.A O no hydrogen 3.125 N/A ALA 315.A N GLU 311.A O no hydrogen 2.898 N/A TRP 316.A N TRP 312.A O no hydrogen 3.084 N/A GLU 317.A N LEU 313.A O no hydrogen 3.056 N/A GLU 318.A N PRO 314.A O no hydrogen 3.047 N/A GLY 319.A N ALA 315.A O no hydrogen 2.847 N/A LEU 320.A N TRP 316.A O no hydrogen 2.883 N/A ARG 321.A N GLU 317.A O no hydrogen 3.099 N/A ARG 321.A NE GLU 318.A OE1 no hydrogen 2.988 N/A ARG 321.A NH2 GLU 318.A OE1 no hydrogen 3.539 N/A ARG 321.A NH2 GLU 318.A OE2 no hydrogen 2.661 N/A ARG 322.A N GLU 318.A O no hydrogen 2.893 N/A ARG 322.A NH2 ALA 106.A O no hydrogen 2.791 N/A ALA 323.A N GLY 319.A O no hydrogen 2.923 N/A SER 324.A N LEU 320.A O no hydrogen 2.986 N/A SER 324.A OG LEU 320.A O no hydrogen 2.956 N/A ALA 325.A N ARG 321.A O no hydrogen 2.986 N/A ALA 326.A N ARG 322.A O no hydrogen 2.884 N/A ILE 327.A N ALA 323.A O no hydrogen 3.319 N/A ASP 328.A N SER 324.A O no hydrogen 2.898 N/A THR 329.A N ALA 325.A O no hydrogen 2.986 N/A THR 329.A OG1 ALA 325.A O no hydrogen 2.836 N/A GLY 330.A N ILE 327.A O no hydrogen 2.988 N/A ALA 332.A N ALA 326.A O no hydrogen 2.938 N/A GLN 334.A N GLY 330.A O no hydrogen 2.802 N/A LEU 335.A N ALA 331.A O no hydrogen 2.812 N/A LEU 336.A N ALA 332.A O no hydrogen 3.006 N/A ALA 337.A N GLU 333.A O no hydrogen 3.184 N/A ARG 338.A N GLN 334.A O no hydrogen 2.910 N/A TRP 339.A N LEU 335.A O no hydrogen 2.772 N/A VAL 340.A N LEU 336.A O no hydrogen 2.869 N/A ARG 341.A N ALA 337.A O no hydrogen 2.867 N/A PHE 342.A N ARG 338.A O no hydrogen 2.871 N/A GLY 343.A N TRP 339.A O no hydrogen 3.219 N/A ARG 344.A N VAL 340.A O no hydrogen 3.133 N/A GLN 345.A N ARG 341.A O no hydrogen 3.113 N/A GLN 345.A N PHE 342.A O no hydrogen 3.272 N/A ILE 346.A N GLY 343.A O no hydrogen 3.334 N/A