==== Secondary Structure Definition by the program DSSP, updated CMBI version by ElmK / April 1,2000 ==== DATE=8-DEC-2009 . REFERENCE W. KABSCH AND C.SANDER, BIOPOLYMERS 22 (1983) 2577-2637 . HEADER HYDROLASE 28-JAN-03 1NSO . COMPND 2 MOLECULE: PROTEASE; . SOURCE 2 ORGANISM_SCIENTIFIC: SIMIAN RETROVIRUS 1; . AUTHOR V.VEVERKA,H.BAUEROVA,A.ZABRANSKY,J.LANG,T.RUML,I.PICHOVA, . 107 1 0 0 0 TOTAL NUMBER OF RESIDUES, NUMBER OF CHAINS, NUMBER OF SS-BRIDGES(TOTAL,INTRACHAIN,INTERCHAIN) . 7605.0 ACCESSIBLE SURFACE OF PROTEIN (ANGSTROM**2) . 56 52.3 TOTAL NUMBER OF HYDROGEN BONDS OF TYPE O(I)-->H-N(J) , SAME NUMBER PER 100 RESIDUES . 2 1.9 TOTAL NUMBER OF HYDROGEN BONDS IN PARALLEL BRIDGES, SAME NUMBER PER 100 RESIDUES . 26 24.3 TOTAL NUMBER OF HYDROGEN BONDS IN ANTIPARALLEL BRIDGES, SAME NUMBER PER 100 RESIDUES . 0 0.0 TOTAL NUMBER OF HYDROGEN BONDS OF TYPE O(I)-->H-N(I-5), SAME NUMBER PER 100 RESIDUES . 1 0.9 TOTAL NUMBER OF HYDROGEN BONDS OF TYPE O(I)-->H-N(I-4), SAME NUMBER PER 100 RESIDUES . 2 1.9 TOTAL NUMBER OF HYDROGEN BONDS OF TYPE O(I)-->H-N(I-3), SAME NUMBER PER 100 RESIDUES . 0 0.0 TOTAL NUMBER OF HYDROGEN BONDS OF TYPE O(I)-->H-N(I-2), SAME NUMBER PER 100 RESIDUES . 0 0.0 TOTAL NUMBER OF HYDROGEN BONDS OF TYPE O(I)-->H-N(I-1), SAME NUMBER PER 100 RESIDUES . 0 0.0 TOTAL NUMBER OF HYDROGEN BONDS OF TYPE O(I)-->H-N(I+0), SAME NUMBER PER 100 RESIDUES . 0 0.0 TOTAL NUMBER OF HYDROGEN BONDS OF TYPE O(I)-->H-N(I+1), SAME NUMBER PER 100 RESIDUES . 14 13.1 TOTAL NUMBER OF HYDROGEN BONDS OF TYPE O(I)-->H-N(I+2), SAME NUMBER PER 100 RESIDUES . 5 4.7 TOTAL NUMBER OF HYDROGEN BONDS OF TYPE O(I)-->H-N(I+3), SAME NUMBER PER 100 RESIDUES . 7 6.5 TOTAL NUMBER OF HYDROGEN BONDS OF TYPE O(I)-->H-N(I+4), SAME NUMBER PER 100 RESIDUES . 2 1.9 TOTAL NUMBER OF HYDROGEN BONDS OF TYPE O(I)-->H-N(I+5), SAME NUMBER PER 100 RESIDUES . 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 *** HISTOGRAMS OF *** . 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 RESIDUES PER ALPHA HELIX . 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 PARALLEL BRIDGES PER LADDER . 3 1 0 1 2 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 ANTIPARALLEL BRIDGES PER LADDER . 1 1 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 LADDERS PER SHEET . # RESIDUE AA STRUCTURE BP1 BP2 ACC N-H-->O O-->H-N N-H-->O O-->H-N TCO KAPPA ALPHA PHI PSI X-CA Y-CA Z-CA 1 1 A W 0 0 261 0, 0.0 2,-0.3 0, 0.0 72,-0.0 0.000 360.0 360.0 360.0 -61.2 8.0 -18.3 4.4 2 2 A V - 0 0 52 18,-0.1 12,-0.1 70,-0.0 70,-0.0 -0.800 360.0-138.5-114.8 157.2 4.3 -17.8 3.4 3 3 A Q B -A 13 0A 117 10,-1.1 10,-0.6 -2,-0.3 2,-0.4 -0.927 22.6-114.5-117.7 140.2 1.1 -18.0 5.4 4 4 A P - 0 0 107 0, 0.0 2,-0.5 0, 0.0 0, 0.0 -0.566 31.3-121.7 -74.5 125.5 -2.2 -19.7 4.3 5 5 A I - 0 0 72 -2,-0.4 2,-0.7 8,-0.1 7,-0.1 -0.536 24.6-156.8 -70.2 118.1 -5.0 -17.2 3.9 6 6 A T - 0 0 113 -2,-0.5 -1,-0.1 5,-0.3 5,-0.1 -0.861 56.1 -34.0-102.4 108.4 -7.9 -18.2 6.2 7 7 A A S S- 0 0 62 -2,-0.7 2,-1.6 1,-0.1 4,-0.2 0.399 96.2 -57.3 61.4 153.8 -11.2 -16.8 5.1 8 8 A Q S S+ 0 0 149 -3,-0.1 19,-0.1 2,-0.1 -1,-0.1 -0.467 91.8 128.1 -66.9 90.3 -11.7 -13.5 3.4 9 9 A K S S- 0 0 130 -2,-1.6 2,-2.9 2,-0.3 16,-1.0 -0.951 75.2 -91.2-143.5 162.0 -10.1 -11.2 6.0 10 10 A P S S+ 0 0 78 0, 0.0 2,-0.3 0, 0.0 16,-0.1 -0.286 92.8 97.3 -71.8 59.0 -7.4 -8.5 6.4 11 11 A S + 0 0 78 -2,-2.9 -5,-0.3 -4,-0.2 2,-0.3 -0.907 38.0 119.6-154.0 121.8 -4.7 -11.1 7.2 12 12 A L E - B 0 23A 10 11,-1.4 11,-1.8 -2,-0.3 2,-0.5 -0.943 44.6-127.7-173.0 154.6 -2.1 -12.7 4.9 13 13 A T E +AB 3 22A 14 -10,-0.6 -10,-1.1 -2,-0.3 60,-0.3 -0.929 41.5 139.6-121.8 113.9 1.7 -13.0 4.5 14 14 A L E - B 0 21A 10 7,-1.6 7,-2.4 -2,-0.5 2,-0.3 -0.837 50.3 -92.2-137.8 173.0 3.4 -12.2 1.2 15 15 A W E -CB 71 20A 57 56,-2.4 56,-3.3 5,-0.3 2,-0.4 -0.682 35.2-169.2 -95.2 145.8 6.6 -10.5 0.1 16 16 A L E > -CB 70 19A 33 3,-3.1 2,-3.4 -2,-0.3 3,-1.1 -0.992 63.1 -16.4-134.9 141.2 6.8 -6.8 -0.7 17 17 A D T 3 S- 0 0 69 52,-1.8 3,-0.1 -2,-0.4 -2,-0.1 -0.324 136.1 -31.8 67.1 -66.8 9.5 -4.7 -2.3 18 18 A D T 3 S+ 0 0 133 -2,-3.4 2,-0.3 1,-0.3 -1,-0.2 0.112 124.6 58.9-173.5 35.0 12.1 -7.5 -1.7 19 19 A K E < S-B 16 0A 167 -3,-1.1 -3,-3.1 2,-0.0 -1,-0.3 -0.937 79.6 -96.8-170.0 146.5 11.2 -9.3 1.5 20 20 A M E +B 15 0A 55 -5,-0.3 -5,-0.3 -2,-0.3 2,-0.3 -0.306 51.3 147.3 -67.1 149.9 8.3 -11.3 3.1 21 21 A F E -B 14 0A 116 -7,-2.4 -7,-1.6 -2,-0.0 2,-0.2 -0.967 41.1 -92.9-168.9 174.4 5.8 -9.5 5.4 22 22 A T E +B 13 0A 72 -2,-0.3 2,-0.3 -9,-0.2 -9,-0.2 -0.477 42.3 149.6 -97.9 171.2 2.2 -9.5 6.6 23 23 A G E -B 12 0A 15 -11,-1.8 -11,-1.4 -2,-0.2 2,-0.4 -0.938 38.2 -91.9-173.1-167.0 -0.8 -7.5 5.3 24 24 A L - 0 0 30 -2,-0.3 2,-0.5 -13,-0.2 69,-0.2 -0.997 22.5-147.8-135.8 136.4 -4.5 -7.4 4.8 25 25 A I - 0 0 16 -16,-1.0 2,-0.4 -2,-0.4 -14,-0.2 -0.886 10.0-153.5-106.5 130.0 -6.7 -8.5 1.9 26 26 A N - 0 0 30 -2,-0.5 3,-0.5 -16,-0.1 -17,-0.1 -0.821 11.1-152.6-102.1 137.9 -10.0 -6.7 1.0 27 27 A T S S+ 0 0 102 -2,-0.4 -1,-0.1 1,-0.2 -19,-0.0 0.336 95.2 38.3 -88.3 7.1 -12.8 -8.6 -0.8 28 28 A G S S+ 0 0 54 0, 0.0 2,-0.3 0, 0.0 -1,-0.2 -0.304 75.4 158.9-154.8 62.2 -14.0 -5.3 -2.2 29 29 A A + 0 0 3 -3,-0.5 65,-0.1 1,-0.1 3,-0.1 -0.654 12.6 167.5 -90.7 145.9 -11.2 -2.9 -3.2 30 30 A D S S+ 0 0 111 1,-0.3 2,-0.4 -2,-0.3 -1,-0.1 0.650 74.3 17.3-121.0 -43.1 -11.6 -0.1 -5.7 31 31 A V S S- 0 0 70 62,-0.2 2,-0.3 63,-0.1 -1,-0.3 -0.955 82.2-117.0-140.1 116.7 -8.4 1.9 -5.2 32 32 A T + 0 0 6 -2,-0.4 51,-2.0 -3,-0.1 2,-0.5 -0.326 40.2 179.0 -54.4 110.1 -5.2 0.7 -3.6 33 33 A I B -eF 83 92B 18 59,-2.5 59,-2.6 -2,-0.3 2,-0.5 -0.968 9.4-177.2-122.3 121.7 -4.7 2.9 -0.5 34 34 A I - 0 0 15 49,-1.2 51,-0.1 -2,-0.5 30,-0.1 -0.966 29.1-117.5-119.0 127.1 -1.9 2.4 1.9 35 35 A K > - 0 0 31 -2,-0.5 3,-1.5 49,-0.2 49,-0.1 -0.087 25.2-111.9 -58.3 160.0 -1.6 4.6 5.0 36 36 A L G > S+ 0 0 25 49,-1.8 3,-2.8 1,-0.3 -1,-0.1 0.780 109.0 79.7 -64.7 -28.2 1.4 6.9 5.5 37 37 A E G 3 S+ 0 0 149 48,-0.3 -1,-0.3 1,-0.3 -2,-0.1 0.628 97.4 46.1 -55.7 -11.9 2.6 4.7 8.4 38 38 A D G < S+ 0 0 73 -3,-1.5 -1,-0.3 2,-0.1 -2,-0.2 0.035 95.0 102.0-119.1 24.0 4.0 2.4 5.6 39 39 A W S < S- 0 0 58 -3,-2.8 6,-0.0 1,-0.0 -3,-0.0 -0.788 85.9 -85.3-110.3 153.8 5.6 5.0 3.4 40 40 A P > - 0 0 35 0, 0.0 3,-1.2 0, 0.0 -2,-0.1 -0.371 30.3-156.7 -57.7 112.4 9.3 6.0 3.1 41 41 A P T 3 S+ 0 0 115 0, 0.0 -4,-0.0 0, 0.0 -5,-0.0 0.603 82.4 83.9 -66.6 -9.7 10.1 8.5 5.8 42 42 A N T 3 S+ 0 0 150 1,-0.2 -3,-0.0 2,-0.0 0, 0.0 0.877 102.8 18.1 -60.6 -40.4 12.9 9.7 3.6 43 43 A W S < S- 0 0 114 -3,-1.2 -1,-0.2 0, 0.0 2,-0.0 -0.998 83.3-114.6-137.8 140.4 10.6 12.0 1.6 44 44 A P - 0 0 116 0, 0.0 2,-0.4 0, 0.0 -2,-0.0 -0.303 28.5-145.5 -69.2 152.8 7.1 13.4 2.3 45 45 A I + 0 0 22 17,-0.1 19,-0.4 19,-0.1 2,-0.3 -0.980 21.5 167.4-129.5 132.4 4.2 12.3 0.1 46 46 A T + 0 0 99 -2,-0.4 17,-0.3 17,-0.2 2,-0.2 -0.986 3.1 172.8-142.8 136.8 1.1 14.3 -1.0 47 47 A D - 0 0 54 -2,-0.3 2,-0.6 37,-0.1 17,-0.1 -0.757 32.3-109.3-133.9-178.4 -1.7 14.0 -3.6 48 48 A T + 0 0 116 -2,-0.2 2,-0.2 14,-0.2 14,-0.1 -0.928 41.5 164.8-116.3 112.2 -5.0 15.5 -4.8 49 49 A L E -G 60 0C 51 11,-1.6 11,-0.5 -2,-0.6 2,-0.4 -0.635 33.5-106.7-118.4 176.2 -8.2 13.6 -4.1 50 50 A T E +G 59 0C 77 9,-0.3 2,-0.3 -2,-0.2 9,-0.3 -0.914 24.4 178.2-113.0 135.1 -11.9 14.5 -4.1 51 51 A N E -G 58 0C 69 7,-1.2 7,-1.2 -2,-0.4 2,-0.7 -0.756 13.6-176.8-131.0 81.0 -14.2 15.0 -1.1 52 52 A L E -G 57 0C 93 -2,-0.3 5,-0.2 5,-0.2 7,-0.1 -0.741 16.8-173.1 -88.5 118.3 -17.6 15.9 -2.5 53 53 A R - 0 0 180 3,-1.0 2,-3.2 -2,-0.7 4,-0.2 0.196 40.6-126.1 -88.3 12.4 -20.2 16.7 0.2 54 54 A G S S+ 0 0 74 1,-0.3 3,-0.2 2,-0.2 -1,-0.1 -0.288 109.0 25.3 74.7 -57.7 -22.9 16.9 -2.5 55 55 A I S S+ 0 0 175 -2,-3.2 2,-0.4 1,-0.2 -1,-0.3 0.533 123.0 59.4-107.4 -16.8 -23.8 20.3 -1.3 56 56 A G S S- 0 0 31 -3,-0.1 -3,-1.0 2,-0.0 2,-0.5 -0.531 79.5-157.0-113.1 63.6 -20.3 20.9 0.2 57 57 A Q E +G 52 0C 169 -2,-0.4 -5,-0.2 -5,-0.2 2,-0.2 -0.155 32.7 160.1 -43.3 93.1 -18.1 20.6 -2.9 58 58 A S E -G 51 0C 56 -7,-1.2 -7,-1.2 -2,-0.5 2,-0.4 -0.613 36.1-122.8-115.0 176.0 -14.9 19.7 -1.1 59 59 A N E -G 50 0C 124 -9,-0.3 -9,-0.3 -2,-0.2 -2,-0.0 -0.965 23.2-120.4-123.9 138.2 -11.5 18.1 -2.0 60 60 A N E -G 49 0C 42 -11,-0.5 -11,-1.6 -2,-0.4 2,-0.2 -0.388 40.4 -91.4 -75.8 153.5 -9.9 15.0 -0.4 61 61 A P - 0 0 40 0, 0.0 -13,-0.1 0, 0.0 -1,-0.1 -0.435 50.2 -89.2 -71.5 133.9 -6.4 15.2 1.2 62 62 A K - 0 0 100 -2,-0.2 2,-0.5 -13,-0.1 -14,-0.2 -0.112 43.2-161.4 -42.3 123.6 -3.3 14.5 -0.8 63 63 A Q - 0 0 11 -17,-0.3 22,-0.3 22,-0.1 -17,-0.2 -0.943 24.1-107.9-117.6 121.7 -2.4 10.8 -0.8 64 64 A S B -H 84 0D 1 20,-2.9 20,-0.9 -2,-0.5 -30,-0.1 0.210 16.1-150.5 -34.5 163.2 1.1 9.7 -1.7 65 65 A S + 0 0 72 18,-0.2 -1,-0.1 -19,-0.1 18,-0.0 0.558 45.3 138.1-115.6 -19.0 1.6 7.9 -5.0 66 66 A K - 0 0 54 15,-0.2 2,-0.2 1,-0.1 14,-0.1 -0.012 52.8-132.2 -34.0 111.8 4.6 5.7 -4.0 67 67 A Y - 0 0 115 14,-0.2 2,-0.3 12,-0.1 14,-0.3 -0.528 16.4-148.4 -79.2 140.5 3.8 2.4 -5.6 68 68 A L E - D 0 80A 16 12,-1.8 12,-1.2 -2,-0.2 2,-0.6 -0.780 3.1-144.8-107.7 151.4 4.0 -0.8 -3.6 69 69 A T E + D 0 79A 13 -2,-0.3 -52,-1.8 10,-0.2 2,-0.5 -0.873 18.5 180.0-121.7 99.8 4.9 -4.3 -4.9 70 70 A W E +CD 16 78A 13 8,-1.9 8,-1.7 -2,-0.6 2,-0.4 -0.852 8.4 168.2-100.6 127.1 3.1 -7.1 -3.2 71 71 A R E -CD 15 77A 50 -56,-3.3 -56,-2.4 -2,-0.5 6,-0.2 -0.999 28.9-126.5-141.7 135.8 3.9 -10.6 -4.4 72 72 A D E >> - D 0 76A 22 4,-1.3 3,-3.7 -2,-0.4 4,-1.3 -0.390 43.3 -91.3 -78.9 159.4 3.1 -14.0 -3.0 73 73 A K T 34 S+ 0 0 108 1,-0.3 -1,-0.1 -60,-0.3 4,-0.1 0.720 125.2 72.1 -39.8 -27.3 5.7 -16.7 -2.3 74 74 A E T 34 S- 0 0 142 2,-0.3 -1,-0.3 1,-0.1 3,-0.1 0.483 122.4-106.7 -71.0 0.4 4.9 -17.9 -5.8 75 75 A N T <4 S+ 0 0 104 -3,-3.7 2,-0.2 1,-0.1 -2,-0.2 0.906 90.5 70.1 75.4 45.0 6.7 -14.7 -7.0 76 76 A N E < +D 72 0A 72 -4,-1.3 -4,-1.3 2,-0.0 -2,-0.3 -0.778 30.2 123.8 174.6 140.7 3.6 -12.8 -8.0 77 77 A S E S-D 71 0A 10 -7,-0.3 24,-0.4 -6,-0.2 -6,-0.3 0.196 71.7 -62.1-168.7 -47.1 0.5 -11.1 -6.7 78 78 A G E -D 70 0A 9 -8,-1.7 -8,-1.9 22,-0.1 2,-0.3 -0.611 35.7-161.4 151.9 147.6 0.3 -7.4 -7.8 79 79 A L E +D 69 0A 73 -10,-0.2 2,-0.3 -2,-0.2 -10,-0.2 -0.919 23.7 141.9-156.4 125.6 1.9 -4.1 -7.7 80 80 A I E -D 68 0A 49 -12,-1.2 -12,-1.8 -2,-0.3 -10,-0.0 -0.985 54.4 -82.8-158.9 163.7 0.6 -0.5 -8.3 81 81 A K - 0 0 154 -14,-0.3 -14,-0.2 -2,-0.3 -15,-0.2 -0.622 53.3-176.6 -76.1 107.4 0.8 3.1 -7.2 82 82 A P - 0 0 3 0, 0.0 2,-0.5 0, 0.0 -49,-0.3 -0.285 29.9 -95.1 -95.2-177.3 -1.7 3.5 -4.2 83 83 A F B -e 33 0B 47 -51,-2.0 -49,-1.2 -52,-0.1 2,-0.6 -0.896 35.0-168.7-106.0 122.7 -2.8 6.4 -2.1 84 84 A V B +H 64 0D 2 -20,-0.9 -20,-2.9 -2,-0.5 -49,-0.2 -0.925 12.8 164.5-118.0 113.1 -1.0 7.1 1.1 85 85 A I > - 0 0 9 -2,-0.6 2,-1.9 -22,-0.3 -49,-1.8 -0.939 44.4-119.0-124.6 145.9 -2.3 9.5 3.7 86 86 A P T 3 S+ 0 0 91 0, 0.0 -51,-0.1 0, 0.0 -2,-0.0 -0.209 101.1 73.5 -78.4 50.3 -1.3 9.9 7.4 87 87 A N T 3 S- 0 0 100 -2,-1.9 3,-0.1 0, 0.0 -52,-0.1 0.258 110.4 -99.5-141.1 6.4 -4.8 9.1 8.6 88 88 A L < - 0 0 63 -3,-1.1 2,-0.3 1,-0.1 -4,-0.1 0.977 28.0-153.3 68.4 84.6 -5.1 5.4 8.0 89 89 A P - 0 0 17 0, 0.0 3,-0.2 0, 0.0 -1,-0.1 0.043 55.9 -91.4 -77.3 29.6 -7.1 5.0 4.7 90 90 A V - 0 0 94 -2,-0.3 -56,-0.1 1,-0.2 -2,-0.0 0.489 57.8-104.4 74.2 2.9 -8.2 1.6 5.9 91 91 A N + 0 0 33 1,-0.1 2,-0.4 -59,-0.0 -57,-0.2 0.914 60.8 166.8 40.6 90.3 -5.2 0.0 4.2 92 92 A L B -F 33 0B 25 -59,-2.6 -59,-2.5 -61,-0.2 -1,-0.1 -0.986 28.8-137.2-135.0 145.1 -6.7 -1.6 1.1 93 93 A W - 0 0 6 -2,-0.4 2,-0.3 -61,-0.3 -63,-0.2 -0.176 37.4 -86.4 -86.3-176.5 -5.2 -3.0 -2.1 94 94 A G > - 0 0 4 -62,-0.2 4,-3.0 -65,-0.1 3,-0.5 -0.702 28.7-114.7 -98.9 150.4 -6.6 -2.5 -5.6 95 95 A R H > S+ 0 0 149 -2,-0.3 4,-2.2 1,-0.3 5,-0.2 0.758 118.4 56.7 -48.9 -26.3 -9.2 -4.5 -7.3 96 96 A D H > S+ 0 0 99 2,-0.2 4,-1.7 3,-0.2 -1,-0.3 0.949 111.4 38.5 -72.1 -50.1 -6.5 -5.6 -9.7 97 97 A L H > S+ 0 0 1 -3,-0.5 4,-3.0 2,-0.2 -2,-0.2 0.896 121.0 46.5 -67.9 -40.3 -4.2 -7.0 -7.0 98 98 A L H X>S+ 0 0 1 -4,-3.0 4,-2.7 2,-0.2 5,-0.9 0.975 107.7 54.8 -65.5 -55.8 -7.1 -8.5 -5.1 99 99 A S H X>S+ 0 0 23 -4,-2.2 5,-2.2 -5,-0.3 4,-1.2 0.889 117.3 38.3 -43.1 -49.2 -8.8 -10.0 -8.1 100 100 A Q H <5S+ 0 0 101 -4,-1.7 -1,-0.2 -5,-0.2 -2,-0.2 0.974 113.0 55.0 -68.1 -57.4 -5.6 -11.8 -8.9 101 101 A M H <5S- 0 0 17 -4,-3.0 -2,-0.2 -24,-0.4 -3,-0.2 0.910 140.9 -52.7 -41.2 -60.4 -4.5 -12.6 -5.3 102 102 A K H <5S+ 0 0 151 -4,-2.7 -3,-0.2 -5,-0.1 -2,-0.2 0.079 113.8 91.2 179.0 49.8 -7.8 -14.4 -4.6 103 103 A I T << + 0 0 48 -4,-1.2 -4,-0.3 -5,-0.9 -3,-0.2 0.675 57.9 94.6-119.7 -39.3 -10.9 -12.3 -5.4 104 104 A M S