In the table you see for each pair of amino acids the exact Cα-Cα distance.
1 THR ( 1 ) A CA - 47 LYS ( 1 ) A CA 1.394 Terminus 2 THR ( 2 ) A CA - 48 SER ( 2 ) A CA 0.443 3 CYS ( 3 ) A CA - 49 CYS ( 3 ) A CA 1.039 4 CYS ( 4 ) A CA - 50 CYS ( 4 ) A CA 0.573 5 PRO ( 5 ) A CA - 51 PRO ( 5 ) A CA 0.115 6 SER ( 6 ) A CA - 52 ASN ( 6 ) A CA 0.606 7 ILE ( 7 ) A CA - 53 THR ( 7 ) A CA 0.844 8 VAL ( 8 ) A CA - 54 THR ( 8 ) A CA 0.697 9 ALA ( 9 ) A CA - 55 GLY ( 9 ) A CA 0.377 10 ARG ( 10 ) A CA - 56 ARG ( 10 ) A CA 0.497 11 SER ( 11 ) A CA - 57 ASN ( 11 ) A CA 0.629 12 ASN ( 12 ) A CA - 58 ILE ( 12 ) A CA 0.488 13 PHE ( 13 ) A CA - 59 TYR ( 13 ) A CA 0.689 14 ASN ( 14 ) A CA - 60 ASN ( 14 ) A CA 0.803 15 VAL ( 15 ) A CA - 61 ALA ( 15 ) A CA 0.480 16 CYS ( 16 ) A CA - 62 CYS ( 16 ) A CA 0.440 17 ARG ( 17 ) A CA - 63 ARG ( 17 ) A CA 0.582 18 LEU ( 18 ) A CA - 64 LEU ( 18 ) A CA 1.216 18 LEU ( 18 ) A CA - 65 THR ( 19 ) A CA 2.693 *** 19 PRO ( 19 ) A CA - 65 THR ( 19 ) A CA 2.036 *** Pro 19 PRO ( 19 ) A CA - 66 GLY ( 20 ) A CA 2.235 *** Pro Gly 20 GLY ( 20 ) A CA - 66 GLY ( 20 ) A CA 1.687 *** (Both Gly) 21 THR ( 21 ) A CA - 67 ALA ( 21 ) A CA 1.329 *** 21 THR ( 21 ) A CA - 68 PRO ( 22 ) A CA 2.736 *** Pro 22 PRO ( 22 ) A CA - 68 PRO ( 22 ) A CA 1.520 *** (both Pro) 22 PRO ( 22 ) A CA - 69 ARG ( 23 ) A CA 2.760 *** Pro 23 GLU ( 23 ) A CA - 69 ARG ( 23 ) A CA 1.142 24 ALA ( 24 ) A CA - 70 PRO ( 24 ) A CA 0.877 25 ILE ( 25 ) A CA - 71 THR ( 25 ) A CA 0.872 26 CYS ( 26 ) A CA - 72 CYS ( 26 ) A CA 0.574 27 ALA ( 27 ) A CA - 73 ALA ( 27 ) A CA 0.531 28 THR ( 28 ) A CA - 74 LYS ( 28 ) A CA 0.614 29 TYR ( 29 ) A CA - 75 LEU ( 29 ) A CA 0.619 30 THR ( 30 ) A CA - 76 SER ( 30 ) A CA 0.451 31 GLY ( 31 ) A CA - 77 GLY ( 31 ) A CA 0.668 32 CYS ( 32 ) A CA - 78 CYS ( 32 ) A CA 0.711 33 ILE ( 33 ) A CA - 79 LYS ( 33 ) A CA 0.744 34 ILE ( 34 ) A CA - 80 ILE ( 34 ) A CA 0.885 35 ILE ( 35 ) A CA - 81 ILE ( 35 ) A CA 0.838 36 PRO ( 36 ) A CA - 82 SER ( 36 ) A CA 1.827 *** Pro 37 GLY ( 37 ) A CA - 82 SER ( 36 ) A CA 2.075 *** Gly 37 GLY ( 37 ) A CA - 83 GLY ( 37 ) A CA 1.941 *** (Both Gly) 38 ALA ( 38 ) A CA - 84 SER ( 38 ) A CA 1.377 *** 39 THR ( 39 ) A CA - 85 THR ( 39 ) A CA 1.600 *** 40 CYS ( 40 ) A CA - 86 CYS ( 40 ) A CA 0.383 41 PRO ( 41 ) A CA - 87 PRO ( 41 ) A CA 0.390 42 GLY ( 42 ) A CA - 88 SER ( 42 ) A CA 0.314 43 ASP ( 43 ) A CA - 89 ASP ( 43 ) A CA 0.245 44 TYR ( 44 ) A CA - 90 TYR ( 44 ) A CA 0.399 45 ALA ( 45 ) A CA - 91 PRO ( 45 ) A CA 1.320 46 ASN ( 46 ) A CA - 92 LYS ( 46 ) A CA 1.747 Terminus |
The termini differ much, because they can, they don't need to compromise at one side. Furthermore, the number of glycines and prolines that are either present or mutated in or out is suspiciously high in the loops that differ most.
Obviously, this is not exam-material. I just hope you grasp the concept that there are many reasons for making errors in homology models!