TorsiFlex: an automatic generator of torsional conformers. Application to the twenty proteinogenic amino acids

Table 1 Number of canonical conformers obtained for the 20 pAAs employing TorsiFlex

Amino acid	HF	DFT	Number of conformers [Ref.]
Asp	169	127	139 [58], 37 [70], 76 [71]
Glu	513	415	143 [70], 165 [69], 197 [71]
Ala	11	11	10 [49], 13 [50], 9 [70], 15 [71]
Gly	12	9	8 [60, 71]
Ile	114	95	12 [65], 59 [70], 76 [71]
Leu	130	95	8 [65], 53 [70], 85 [71]
Pro	20	16	18 [52], 3 [70], 22 [71]
Val	35	30	6 [65], 19 [70], 22 [71]
Asn	91	64	62 [55], 23 [70], 49 [71]
Gln	271	181	72 [70], 143 [68], 134 [71]
Phe	41	35	37 [57], 20 [70], 25 [71]
Trp	95	76	45 [53], 37 [70], 57 [71]
Tyr	80	65	76 [54], 38 [70], 43 [71]
Arg	3 199	2 811	520 [70], 1 218 [71]
HisD	76	60	10 [64], 57 [71]
HisE	93	70	15 [64], 47 [71]
Lys	2 224	1 944	927 [61], 391 [70], 733 [71]
Ser	73	64	51 [49], 74 [66], 30 [70], 59 [71]
Thr	68	58	56 [63], 65 [66], 29 [70], 47 [71]
Cys	79	66	42 [49], 71 [62], 87 [66], 50 [70], 99 [71]
Met	271	216	27 [48], 113 [70], 246 [71]

Second and third columns list the number of conformers obtained at the LL and HL, respectively. The last row indicates the number of conformers obtained in previous works with the reference between square brackets. Two histidine tautomers, HisD, and HisE have been considered (also referred in literature as His[N\(^\tau\)H] and His[N\(^\pi\)H], respectively). HF and DFT refer to the HF/3-21G and M08-HX/MG3S levels, respectively

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