Alanine analogs dipeptides

Head-Gordon, T., M. Head-Gordon, M. J. Frisch, C. Brooks HI, and J. A. Pople. 1989. A Theoretical Study of Alanine Dipeptide and Analogs. Int. J. Quantum Chem. Quantum Biol. Symp. 16, 311-322. 

Yang S, Cho M (2009) Direct calculations of vibrational absorption and circular dichroism spectra of alanine dipeptide analog in water quantum mechanical/molecular mechanical molecular dynamics simulations. J Chem Phys 131 135102-1-135102-8... 

The glycine and alanine dipeptide analogs (GDA and ADA) have recently garnered theoretical attention, because they are the two simplest models of a polypeptide. Molecular mechanical force fields designed to model proteins are often parameterized to reproduce, as well as possible, the geometries and relative energies of the various GDA and ADA conformers. Since few experimental data are available, one must rely on theoretical studies. To date, DFT calculations on peptides have been limited to GDA and ADA. ... 

Table 4 HF , MP2 , DFT <>, i i Values (in Degrees) for the Glycine and Alanine Dipeptide Analogs (from Reference 12)...

D-cycloserine is a competitive inhibitor of both the alanine racemase which catalyses the reversible interconversion of the two optical antipodes (L-alanine - D-alanine) and of the D-alanyl-D-alanine synthetase. Consequently, D-cycloserine blocs the synthesis of the muramyl nucleotide precursor (Fig. 4) at an early stage and induces the accumulation of the incomplete precursor UDP-MurNAc-Xi-y-D-Glu-Xa which lacks the essential terminal D-alanyl-D-alanine dipeptide. It is believed that the molecular basis for the D-cycloserine inhibition lies in the structural analogy between the antibiotic and D-alanine (Fig. 7)... 

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