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2016-03-18

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Please use this identifier to cite or link to this item: https://hdl.handle.net/2445/99326

Proline cis-​trans isomerization and its implications for the dimerization of analogues of cyclopeptide stylostatin 1: a combined computational and experimental study

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http://dx.doi.org/10.1039/c5cp05937b

Abstract

Cis and trans proline conformers are often associated with dramatic changes in the biological function of peptides. A slow equilibrium between cis and trans Ile-Pro amide bond conformers occurs in constrained derivatives of the native marine cyclic heptapeptide stylostatin 1 (cyclo-(NSLAIPF)), a potential anticancer agent. In this work, four cyclopeptides, cyclo-(NSTAIPF), cyclo-(KSTAIPF), cyclo-(RSTAIPF) and cyclo-(DSTAIPF), which are structurally related to stylostatin 1, are experimentally and computationally examined in order to assess the effect of residue mutations on the cis-trans conformational ratio and the apparent capacity to form dimeric aggregates. Primarily, cyclo-(KSTAIPF) and cyclo-(RSTAIPF) showed specific trends in circular dichroism, MALDI-TOF and HPLC purification experiments, which suggests the occurrence of peptide dimerization. Meanwhile, the NMR spectrum of cyclo-(KSTAIPF) indicates that this cyclopeptide exists in the two slow-exchange families of conformations mentioned above. Molecular dynamics simulations combined with quantum mechanical calculations have shed light on the factors governing the cis/trans conformational ratio. In particular, we have found that residue mutations affect the internal hydrogen bond pattern which ultimately tunes the cis/trans conformational ratio and that only trans conformers are capable of aggregating due to the shape complementarity of the two subunits.

Subject

Química orgànica, Pèptids

Subject (English)

Organic chemistry, Peptides

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Articles publicats en revistes (Farmacologia, Toxicologia i Química Terapèutica)
Articles publicats en revistes (Centres Científics i Tecnològics de la Universitat de Barcelona (CCiTUB))
Articles publicats en revistes (Institut de Biomedicina (IBUB))

Citation

LÓPEZ MARTÍNEZ, Carlos, et al. Proline cis-​trans isomerization and its implications for the dimerization of analogues of cyclopeptide stylostatin 1: a combined computational and experimental study. Physical Chemistry Chemical Physics. 2016. Vol. 18, num. 18, pags. 12755-12767. ISSN 1463-9076. [consulted: 19 of August of 2026]. Available at: https://hdl.handle.net/2445/99326

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