Dataset Information

Crystal structures of Z-Gly-Aib-O-·0.5Ca2+·H2O and Z-Gly-Aib-OH.

ABSTRACT: Both deprotonated and neutral achiral title dipeptides assume similar structures of two conformations, which are related by a unit-cell inversion centre. Two mol-ecules of both conformations of the metal-free neutral dipeptide are linked by two hydrogen bonds, while two mol-ecules of both conformations of the ionized form coordinate a calcium ion in calcium(II) bis-[2-(2-{[(benz-yl-oxy)carbon-yl]amino}-acetamido)-2-methyl-propano-ate] monohydrate, 0.5Ca2+·C14H17N2O5-·0.5H2O, which lies on an inversion centre and forms a distorted octa-hedral complex with the metal ion. These CaII complexes are connected in the crystal via hydrogen bonds in the b- and c-axis directions, whereas in the a-axis direction, they stack via apolar contacts. In the metal-free crystal, namely 2-(2-{[(benz-yloxy)carbon-yl]amino}-acetamido)-2-methyl-propanoic acid, C14H18N2O5, mol-ecules are hydrogen bonded in the a- and c-axis directions, and stack in the b-axis direction via apolar contacts.

SUBMITTER: Gessmann R

PROVIDER: S-EPMC6073005 | biostudies-literature | 2018 Aug

REPOSITORIES: biostudies-literature

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Publications

Crystal structures of Z-Gly-Aib-O-·0.5Ca2+·H2O and Z-Gly-Aib-OH.

Gessmann Renate R Brückner Hans H Petratos Kyriacos K

Acta crystallographica. Section E, Crystallographic communications 20180727 Pt 8

Both deprotonated and neutral achiral title dipeptides assume similar structures of two conformations, which are related by a unit-cell inversion centre. Two mol-ecules of both conformations of the metal-free neutral dipeptide are linked by two hydrogen bonds, while two mol-ecules of both conformations of the ionized form coordinate a calcium ion in calcium(II) bis-[2-(2-{[(benz-yl-oxy)carbon-yl]amino}-acetamido)-2-methyl-propano-ate] monohydrate, 0.5Ca2+·C14H17N ...[more]

PMID: 30116587

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Project description:We report results from a computational investigation of the oxidative deboronation of boroglycine, H2N-CH2-B(OH)2, using H2O and H2O2 as the reactive oxygen species (ROS) to yield aminomethanol, H2N-CH2-OH; these results complement our study on the protodeboronation of boroglycine to produce methylamine, H2N-CH3 (Larkin et al. J. Phys. Chem. A 2007, 111, 6489-6500). Second-order Møller-Plesset (MP2) perturbation theory with Dunning-Woon correlation-consistent (cc) basis sets were used for the calculations with comparisons made to results from density functional theory (DFT) at the PBE1PBE/6-311++G(d,p)(cc-pVDZ) levels. The effects of a bulk aqueous environment were also incorporated into the calculations employing PCM and CPCM methodology. Using H2O as the ROS, the reaction H2O + H2N-CH2-B(OH)2 --> H2N-CH2-OH + H-B(OH)2 was calculated to be endothermic; the value of DeltaH(298)(0) was +12.0 kcal/mol at the MP2(FC)/cc-pVTZ computational level in vacuo and +13.7 kcal/mol in PCM aqueous media; the corresponding value for the activation barrier, DeltaH(double dagger), was +94.3 kcal/mol relative to the separated reactants in vacuo and +89.9 kcal/mol in PCM aqueous media. In contrast, the reaction H2O2 + H2N-CH2-B(OH)2 --> H2N-CH2-OH + B(OH)3 was calculated to be highly exothermic with an DeltaH(298)(0) value of -100.9 kcal/mol at the MP2(FC)/cc-pVTZ computational level in vacuo and -99.6 kcal/mol in CPCM aqueous media; the highest-energy transition state for the multistep process associated with this reaction involved the rearrangement of H2N-CH2-B(OH)(OOH) to H2N-CH2-O-B(OH)2 with a DeltaH(double dagger) value of +23.2 kcal/mol in vacuo relative to the separated reactants. These computational results for boroglycine are in accord with the experimental observations for the deboronation of the FDA approved anticancer drug bortezomib (Velcade, PS-341), where it was found to be the principle deactivation pathway (Labutti et al. Chem. Res. Toxicol. 2006, 19, 539-546).

Dataset Information

Crystal structures of Z-Gly-Aib-O-·0.5Ca2+·H2O and Z-Gly-Aib-OH.

Publications

Crystal structures of <i>Z</i>-Gly-Aib-O<sup>-</sup>·0.5Ca<sup>2+</sup>·H<sub>2</sub>O and <i>Z</i>-Gly-Aib-OH.

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