M. Ramek and M. Flock, Ab-initio SCF investigation of gamma-aminobutyric acid, Amino Acids 8, 271-289 (1995).

Publication summary:

The potential energy surface of the neutral form of -aminobutyric acid (GABA) was investigated by means of ab initio 4-31G SCF calculations. Geometries, energies, and selected wave numbers of all 62 symmetry unique local minima are reported. Intramolecular interactions and all reactions, which involve the intramolecular hydrogen bond, are discussed and compared with those present in the homologues -alanine and glycine.

Interactive viewing:

The following list contains links to all 62 RHF/4-31G optimized GABA conformers, labeled by their relative energy in kJ/mol. These links return the coordinates in alchemy format, intended for interactive viewing via RasMol. As a prerequisite, RasMol has to be installed and set up as a helper application of the WWW-browser, in a form similar to the following (which works for Netscape 3.x or 4.x running on a Unix platform; a more detailed description of configuration details can be found elsewhere).

MIME-Type:	chemical/x-alc
Suffix:	alc
Application:	/...path.../rasmol -alchemy %s > /dev/null

Viewers that experience difficulties in recognizing two colored dots in the little graphic next to this paragraph should adjust the RasMol background color by using a command similar to the following, and experiment to find a suitable triple of numbers between 0 and 255.

Application:

echo 'background [51,51,51]' | /...path.../rasmol -alchemy %s > /dev/null

1.   0.000  
2.   0.840  
3.   1.571  
4.   2.263  
5.   4.197  
6.   6.207  
7.   6.734  
8.   6.849  
9.   6.960  
10.   7.281  
11.   7.382  
12.   7.398  
13.   7.473  
14.   8.132  
15.   8.273  
16.   8.290  
17.   8.604  
18.   8.808  
19.   8.969  
20.   9.161  
21.   9.428  
22.   9.905  
23. 10.157  
24. 10.272  
25. 10.393  
26. 10.425  
27. 10.654  
28. 11.352  
29. 11.435  
30. 11.640  
31. 11.995  
32. 12.152  
33. 13.245  
34. 15.499  
35. 31.062  
36. 31.913  
37. 32.231  
38. 34.017  
39. 39.022  
40. 39.604  
41. 40.239  
42. 40.987  
43. 41.059  
44. 41.277  
45. 41.902  
46. 42.048  
47. 42.117  
48. 42.370  
49. 42.567  
50. 42.930  
51. 43.072  
52. 44.296  
53. 45.418  
54. 45.681  
55. 45.942  
56. 45.961  
57. 46.944  
58. 47.193  
59. 48.105  
60. 49.099  
61. 49.263  
62. 50.181  

Related links:

• More on -aminobutyric acid,
• Tour of H-bond results;
   
• Michaela Flock,
• Michael Ramek;
   
• Quantum Chemistry Group.