A combined computational and experimental study on the polymerization of ϵ-caprolactone

This paper reports the study on the synthesis of poly(ϵ-caprolactone) - PCL by ring-opening polymerization (ROP) of ϵ-caprolactone (CL) monomer with focus on mathematic developing of the growth mechanisms of polymer chain. Kinetics and mathematical modeling of ROP of CL was carried out to replicate the different experimental conditions. The computational results of conversion and molecular weight of the polymer were found to be comparable with the experimental results of nuclear magnetic resonance (NMR) spectroscopy and showed that the polymerization is highly dependent on the moisture (ROH). Moreover, parametric studies have shown how the concentrations of octanoic acid and catalyst affect the conversion and molecular weight of the polymer. The study here presented provides further understanding of synthesis of PCL, reporting mathematical models of PCL synthesis which can be used for predicting the characteristic of this biocompatible and biodegradable polymer. © 2018 American Chemical Society57401338713395FAPESP – Fundação de Amparo à Pesquisa Do Estado De São Paulo2016/09588-9; 2016/19847-

Structure, Dynamics, and RNA Interaction Analysis of the Human SBDS Protein

Shwachman–Bodian–Diamond syndrome is an autosomal recessive genetic syndrome with pleiotropic phenotypes, including pancreatic deficiencies, bone marrow dysfunctions with increased risk of myelodysplasia or leukemia, and skeletal abnormalities. This syndrome has been associated with mutations in the SBDS gene, which encodes a conserved protein showing orthologs in Archaea and eukaryotes. The Shwachman–Bodian–Diamond syndrome pleiotropic phenotypes may be an indication of different cell type requirements for a fully functional SBDS protein. RNA-binding activity has been predicted for archaeal and yeast SBDS orthologs, with the latter also being implicated in ribosome biogenesis. However, full-length SBDS orthologs function in a species-specific manner, indicating that the knowledge obtained from model systems may be of limited use in understanding major unresolved issues regarding SBDS function, namely, the effect of mutations in human SBDS on its biochemical function and the specificity of RNA interaction. We determined the solution structure and backbone dynamics of the human SBDS protein and describe its RNA binding site using NMR spectroscopy. Similarly to the crystal structures of Archaea, the overall structure of human SBDS comprises three well-folded domains. However, significant conformational exchange was observed in NMR dynamics experiments for the flexible linker between the N-terminal domain and the central domain, and these experiments also reflect the relative motions of the domains. RNA titrations monitored by heteronuclear correlation experiments and chemical shift mapping analysis identified a classic RNA binding site at the N-terminal FYSH (fungal, Yhr087wp, Shwachman) domain that concentrates most of the mutations described for the human SBDS