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Study of 1,6-bis-O-(N-propionyl-L-alanyl)-1,6-hexanediol as a model compound of poly(ester amide)s derived from L-alanine (1998)

Urpí, Lourdes ; Rodríguez-Galán, Alfonso ; Puiggalí, Jordi

Springer

Journal of chemical crystallography 28 (1998), S. 605-610

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ISSN: 1572-8854

Keywords: Poly(ester amide)s ; alanine ; x-ray crystallography

Source: Springer Online Journal Archives 1860-2000

Topics: Geosciences , Physics

Notes: Abstract The conformation of 1,6-bis-O-(N-propionyl-L-alanyl)-1,6-hexanediol (PrAHAPr) has been investigated in the crystalline state by X-ray analysis. PrAHAPr crystallizes in the monoclinic system, space group P21 with a = 4.861(4), b = 26.24 (1), c = 8.716 (3) Å and β = 105.25 (1)°. In the crystal, the molecules are hydrogen bonded in a single direction that runs parallel to the a crystallographic axis. In spite of its chemical symmetry the molecule adopts an asymmetric conformation, where one of the alanine residues takes a folded conformation. PrAHAPr belongs to a series of model compounds for poly(ester amide)s derived from amino acids that we are presently investigating.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1023/A:1022408925519

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Towards the Understanding of the Folding of Methylene Units in the Glutamine Residue (1996)

Alemán, Carlos ; Vega, M. Cristina ; Navarro, Eloísa ; [et al.]

New York, NY [u.a.] : Wiley-Blackwell

Journal of Peptide Science 2 (1996), S. 364-370

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ISSN: 1075-2617

Keywords: conformation ; glutamine ; folding ; simulation ; Chemistry ; Biochemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: The conformational preferences of the methylenic sequence in the side chain of the glutamine residue were investigated by ab initio and semi-empirical quantum mechanical calculations and examination of both the Brookhaven Protein Databank and Cambridge Structural Data Base. The results were analysed on the basis of our previous findings about the folding of methylene groups in aliphatic segments. Both energy calculations and the crystallographic structure of small peptides indicate that methylene units of the glutamine residue tend to fold in a gauche conformation. In contrast, such groups usually adopt an all-trans conformation in proteins due basically to the entropic and solvent contributions. These results have been demonstrated by computing the entropic correction to the free energy and evaluating the solvent effects through SCRF calculations

Additional Material: 3 Ill.