Improving the alkaline stability of pepsin through rational protein design using renin, an alkaline-stable aspartic protease, as a structural and functional reference.

The present study sought to identify the structural determinants of aspartic protease structural stability and activity at elevated pH. Various hypotheses have been published regarding the features responsible for the unusual alkaline structural stability of renin, however, few structure-function studies have verified these claims. Using pepsin as a model system, and renin as a template for functional and structural alkaline stability, a rational re-design of pepsin was undertaken to identify residues contributing to the alkaline instability of pepsin-like aspartic proteases in regards to both structure and function.

Alkaline conditions stimulate the production of 1,3-propanediol in Lactobacillus panis PM1 through shifting metabolic pathways.

A novel Lactobacillus panis PM1 isolate was found to be capable of converting glycerol to 1,3-propanediol (1,3-PDO), an increasingly valuable commodity chemical. In this study the effects of various process parameters, including glucose and glycerol concentrations, inoculum size, temperature, aeration, pH, and carbon source were examined to determine the optimal conditions for the production of 1,3-PDO using a culture method simulating late log to early stationary phases. Inoculum size did not influence the production of 1,3-PDO, and temperature variance showed similar 1,3-PDO production between 25 and 37 °C under the examined conditions.

Isolation and characterization of novel 1,3-propanediol-producing Lactobacillus panis PM1 from bioethanol thin stillage.

Conversion of glycerol to 1,3-propanediol (1,3-PDO) is an attractive option to increase the economic efficiency of the biofuel industry. A bacterial strain that produced 1,3-PDO in the presence of glycerol was isolated from thin stillage, the fermentation residue of bioethanol production. This 1,3-PDO-producing organism was identified as Lactobacillus panis through biochemical characteristics and by 16S rRNA sequencing.

Influence of positional isomers on the macroscale and nanoscale architectures of aggregates of racemic hydroxyoctadecanoic acids in their molecular gel, dispersion, and solid states.

Inter/intramolecular hydrogen bonding of a series of hydroxystearic acids (HSAs) are investigated. Self-assembly of molecular gels obtained from these fatty acids with isomeric hydroxyl groups is influenced by the position of the secondary hydroxyl group. 2-Hydroxystearic acid (2HSA) does not form a molecular dimer, as indicated by FT-IR, and growth along the secondary axis is inhibited because the secondary hydroxyl group is unable to form intermolecular H-bonds.