Role of aromatic residues in stabilization of the [Fe4S4] cluster in high-potential iron proteins (HiPIPs): physical characterization and stability studies of Tyr-19 mutants of Chromatium vinosum HiPIP.

The functional role of residue Tyr-19 of Chromatium vinosum HiPIP has been evaluated by site-directed mutagenesis experiments. The stability of the [Fe4S4] cluster prosthetic center is sensitive to side-chain replacements. Polar residues result in significant instability, while nonpolar residues (especially with aromatic side chains) maintain cluster stability. Two-dimensional NMR data of native and mutant HiPIPs are consistent with a model where Tyr-19 serves to preserve the structural rigidity of the polypeptide backbone, thereby maintaining a hydrophobic barrier for exclusion of water from the cluster cavity. Solvent accessibility results in more facile oxidation of the cluster by atmospheric oxygen, with subsequent rapid hydrolysis of the [Fe4S4]3+ core.

Stabilization of APIs and nutraceuticals through cocrystallization and molecular confinement

Cocrystallization of the molecule of interest could be a smart and dainty way to tune solubility properties of solid phases leaving the molecule chemically unchanged, hence it is widely investigated by companies and by solid state scientists. Despite of this extremely high interest towards cocrystallization no particular emphasis has been paid to using it as a means to stabilize liquid molecules. In this work we define a benchmark of relevant molecules for human health that have been combined with suitable partners according to crystal engineering methods in order to obtain cocrystals. Solubility properties in different solvents of cocrystals new solid phases have been tested and compared to the properties of the drugs. A further approach to deal with volatile compounds is molecular confinement inside molecular scaffold. Nowadays metal organic frameworks (MOFs) are studied in many fields ranging from catalysis to trapping or storage of gases, such as hydrogen, methane, CO2 thanks to their extremely high porosity. Our goal is to confine liquid guests of biological relevance inside MOF pores, monitoring via X-ray diffraction, spectroscopy and thermal analysis the stabilization of the molecule of interest inside the cavities.

Productivity performance and the American economy : hearings before the Subcommittee on Economic Stabilization of the Committee on Banking, Finance, and Urban Affairs, House of Representatives, Ninety-sixth Congress, second session, June 24, July 29, 31, August 27, 1980.

Mode of access: Internet.

Defense Production Act Amendments of the Energy Security Act of 1980 : hearings before the Subcommittee on Economic Stabilization of the Committee on Banking, Finance, and Urban Affairs, House of Representatives, Ninety-sixth Congress, second session, July 30, and October 1, 1980.

"Serial no. 96-69."

The Oil Shale Corporation loan guarantee contract : hearing before the Subcommittee on Economic Stabilization of the Committee on Banking, Finance, and Urban Affairs, House of Representatives, Ninety-seventh Congress, first session, October 1, 1981.

Mode of access: Internet.