Differential production levels of intracellular amino acids among wt-pvtu, ∆<i>idh1/2</i>-pvtu and ∆<i>idh1/2</i>-<i>acl</i> strains.

<p>Three independent experiments were carried out. The amino acid levels in wt-pvtu strain were taken as controls and the amino acid levels in ∆<i>idh1/2</i>-pvtu and ∆<i>idh1/2</i>-<i>acl</i> strains were calculated accordingly.</p

Schematic diagram of metabolic pathway changes in <i>S</i>.

<div><p><b><i>cerevisiae</i> engineered strains</b>. </p> <p>The engineered pathway in yeast with enhanced fatty acid synthesis was indicated by red dashed box. Both of the up-regulated and down regulated metabolic pathways in ∆<i>idh1/2</i>-<i>acl</i> strain were indicated by the different colored arrows. The proteins involved in other pathways that haven’t been detected from LC-MS/MS analysis were not shown in this diagram. </p></div

Comparative Proteomics Analysis of Engineered <i>Saccharomyces cerevisiae</i> with Enhanced Biofuel Precursor Production

<div><p>The yeast <i>Saccharomyces cerevisiae</i> was metabolically modified for enhanced biofuel precursor production by knocking out genes encoding mitochondrial isocitrate dehydrogenase and over-expression of a heterologous ATP-citrate lyase. A comparative iTRAQ-coupled 2D LC-MS/MS analysis was performed to obtain a global overview of ubiquitous protein expression changes in <i>S. cerevisiae</i> engineered strains. More than 300 proteins were identified. Among these proteins, 37 were found differentially expressed in engineered strains and they were classified into specific categories based on their enzyme functions. Most of the proteins involved in glycolytic and pyruvate branch-point pathways were found to be up-regulated and the proteins involved in respiration and glyoxylate pathway were however found to be down-regulated in engineered strains. Moreover, the metabolic modification of <i>S. cerevisiae</i> cells resulted in a number of up-regulated proteins involved in stress response and differentially expressed proteins involved in amino acid metabolism and protein biosynthesis pathways. These LC-MS/MS based proteomics analysis results not only offered extensive information in identifying potential protein-protein interactions, signal pathways and ubiquitous cellular changes elicited by the engineered pathways, but also provided a meaningful biological information platform serving further modification of yeast cells for enhanced biofuel production.</p> </div

One-Pot Synthesis of Redox-Labile Polymer Capsules via Emulsion Droplet-Mediated Precipitation Polymerization

Monodisperse poly­(vinylcaprolactam) (PVCL)-based capsules are prepared by precipitation polymerization of vinylcaprolactam (VCL) onto dimethyldiethoxysilane (DMDES) emulsion droplets and removal of the DMDES templates by ethanol. Polymer chains in the shells can be cross-linked during the polymerization by disulfide-containing cross-linker <i>N</i>,<i>N</i>′-bis­(acryloyl) cystamine, which endows the capsules with an excellent redox-labile property. Versatility of this technique to prepare capsules with diverse components is demonstrated by the copolymerization of methacrylic acid (MAA) and VCL in the shell to prepare poly­(vinylcaprolactam-<i>co</i>-methacrylic acid) (P­(VCL-<i>co</i>-MAA)) capsules. The disulfide-bonded capsules can degrade efficiently into low molecular weight species (ca. 1200 Da) when the capsules are incubated with 10 mM glutathione (GSH) as the reducing agent. Delivery of the anticancer drug (doxorubicin, DOX) was also investigated in the P­(VCL-<i>co</i>-MAA) capsules. The cumulative <i>in vitro</i> release of DOX-loaded capsules allows a relatively low DOX release at pH 7.4. However, a burst release (ca. 90% in 6 h) of DOX was observed in the presence of 10 mM GSH. Cell viability assays show that the P­(VCL-<i>co</i>-MAA) capsules have negligible cytotoxicity to HeLa cancer cells. In comparison, DOX-loaded P­(VCL-<i>co</i>-MAA) capsules cause significant cell death following internalization. The reported capsules represent a novel and versatile class of stimuli-responsive carriers for controlled drug delivery