Research Article
Nearest-Neighbor Interactions and Their Influence on the Structural Aspects of Dipeptides
Table 4
Calculated dihedral angles (in degrees) of the dipeptides at B3LYP/6-311++G(d,p) level of theory; the gas phase values are given in brackets.
| | Dipeptides | –SC Groups |
C3–C4–N6–C7 | O11–C4–N6–H10 | C3–C4–N6–H10 | O11–C4–N6–C7 | | ϕ | |
| | Sec-Val | –CH(CH3)2 | 176.4 (171.9) | −178.8 (−178.9) | −0.5 (−0.3) | −1.9 (−6.6) | 19.8 (28.4) | −95.8 (−103.7) | 137.7 (129.3) | | Sec-Leu | –CH2CH(CH3)2 | 176.4 (172.5) | −178.0 (−179.0) | 0.4 (0.1) | −2.0 (−6.7) | 18.3 (24.8) | −73.4 (−91.9) | 162.9 (142.5) | | Sec-Asp | –CH2CO2H | 175.8 (−169.6) | −178.9 (169.0) | −0.6 (−11.4) | −2.6 (10.7) | 20.6 (33.1) | −99.0 (−131.8) | 135.7 (103.6) | | Sec-Ser | –CH2OH | 177.4 (176.5) | 178.3 (174.1) | −3.5 (−7.7) | −0.8 (−1.7) | 21.3 (30.3) | −118.4 (−135.7) | 117.8 (100.6) | | Sec-Gln | –(CH2)2CONH2 | 178.5 (175.3) | 179.8 (−177.8) | −2.2 (1.2) | 0.5 (−3.7) | 22.2 (22.9) | −65.4 (−80.9) | 170.8 (154.5) | | Sec-His | –(CH2)2C3N2H3 | 178.4 (177.1) | 177.1 (173.5) | −4.7 (−8.3) | 0.2 (−1.2) | 23.7 (30.7) | −108.5 (−131.4) | 126.1 (103.9) | | Sec-Pyl | –(CH2)4NHCO(C5NH8) | 177.1 (174.7) | −178.1 (179.3) | 0.5 (−2.2) | −1.4 (−3.8) | 18.3 (27.2) | −83.0 (−118.5) | 152.8 (117.4) |
| | MDa | | 4.2 (10.4) | 2.9 (11.0) | 4.7 (11.4) | 2.6 (10.7) | | | |
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Maximum deviation from expected values.
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