Consistent force field calculations on 2,5-diketopiperazine and its 3.6-dimethyl derivatives

✍ Scribed by Susan Karplus; Shneior Lifson

• Publisher: Wiley (John Wiley & Sons)
• Year: 1971
• Tongue: English
• Weight: 449 KB
• Volume: 10
• Category: Article
• ISSN: 0006-3525
• DOI: 10.1002/bip.360101014

✦ Synopsis

The niiiiimirin eiiergy coiiforrnatioiia are calcu1at.ed for P,.i-diketopiperasiiie ( I )Kl' ) and its 3,Mimethyl derivatives (DL-DMDKP and LL-DMDKP), usiiig a coiisisteiil force field approach developed previously. The energy funct,ion parameters that were not required in earlier calculations 011 alkalies, amides, and lartanis are fitted I ( , dpectral and conformational data oil the diket,opiperasines. Vibrational assigrimeiif~s arc suggested for DKP.

Conformational energies are also det.ermined over a range of selected values for riiig dihedral angles, and t.he shape of the pot,ential energy funct,ioris is examined over devirltioiis from planarity. 1)KP and LL-DMDKP are found t,o have non-plaiiar miiiirniiin energy conformations, separated from planar by less than a kcal/mole. 1IL-l)AlKP exhibits a nearly flat trough about the planar conformation. Calculations of mininiiinr eiiergies with one dihedral angle coordinate constraiiited show a coupling between bond :LiigIes arid dihedral aiigles in agreement with recent siiggestiolis of Beliedelti ]!I73 0 ! ! ) i l I)) J ~I I I Wilej & Son-, IIIC..