Purification, Characterization, and Specificity Determination of a New Serine Protease Secreted by Penicillium waksmanii

The purpose of this work was to purify a protease from Penicillium waksmanii and to determine its biochemical characteristics and specificity. The extracellular protease isolated that was produced by P. waksmanii is a serine protease that is essential for the reproduction and growth of the fungus. The protease isolated showed 32 kDa, and has optimal activity at pH 8.0 and 35 °C towards the substrate Abz-KLRSSKQ-EDDnp. The protease is active in the presence of CaCl₂, KCl, and BaCl, and partially inhibited by CuCl₂, CoCl₂ and totally inhibited by AlCl₃ and LiCl. In the presence of 1 M urea, the protease remains 50 % active. The activity of the protease increases 60 % when it is exposed to 0.4 % nonionic surfactant-Triton X-100 and loses 10 % activity in the presence of 0.4 % Tween-80. Using fluorescence resonance energy transfer analysis, the protease showed the most specificity for the peptide Abz-KIRSSKQ-EDDnp with k _cat/K _m of 10,666 mM^?1?s^?1, followed by the peptide Abz-GLRSSKQ-EDDnp with a k _cat/K _m of 7,500 mM^?1?s^?1. Basic and acidic side chain-containing amino acids performed best at subsite S₁. Subsites S₂, S₃, S^′ ₂, and S^′ ₁, S^′ ₃ showed a preference for binding for amino acids with hydrophobic and basic amino acid side chain, respectively. High values of k _cat/K _m were observed for the subsites S₂, S₃, and S^′ _2. The sequence of the N-terminus (ANVVQSNVPSWGLARLSSKKTGTTDYTYD) showed high similarity to the fungi Penicillium citrinum and Penicillium chrysogenum, with 89 % of identity at the amino acid level.     

Phosphonium Diaza-Diylids and Aza-Yldiid as New and Efficient Reagents For Primary and Secondary Amines Synthesis

Abstract

Metallated aminophosphonium ylids, diaza-diylids and azayldiid, are investigated as reagents for primary and secondary amines synthesis.     

Toxic organophosphorus esters hydrolysis enhanced by onium perborates

The addition of equimolecular quantities of phosphonium salts to an aqueous sodium perborate solution (Na⁺ PB⁻) greatly enhances he efficiency of Na⁺ PB⁻ as a reagene that destroys organophosphorus esters, such as p-nitrophenyldiethyl phosphate or ethyl p-nitrophenyl methylphosphonate.     

Synthesis and study of poly(ethylene oxide) membranes obtained from homopolymerization of peo macromonomers

Hydrogels were obtained by free-radical polymerization of bifunctional macromonomers. This reaction can be conducted in water solution or in organic solvent. The k_p value is yet strongly depending on the solvent used. The properties of these networks will be compared to those of networks obtained by end-linking procedures. These materials were also used as a semi-permeable membrane in the conception of an artificial pancreas.