Calcium-ion-induced stabilization of the protease from Bacillus cereus WQ9-2 in aqueous hydrophilic solvents: effect of calcium ion binding on the hydration shell and intramolecular interactions

Topical delivery of chemotherapeutic drugs using nano-hybrid hydrogels to inhibit post-surgical tumour recurrence

Residual microtumours after surgical resection leading to tumour relapse is one of the major challenges for cancer therapy. Herein, we developed a nano-hybrid oligopeptide hydrogel for topical delivery of a chemotherapeutic drug, docetaxel (DTX), to inhibit the post-surgical tumour recurrence. This nano-hybrid hydrogel (DTX-CTs/Gel) was prepared by encapsulating DTX in cell-penetrating peptide-modified transfersomes followed by embedment in an oligopeptide hydrogel. The obtained DTX-CTs/Gel showed paintable and injectable properties, and could support prolonged retention at the administrated sites after topical administration. DTX-CTs released from the hydrogel presented high skin and tumour penetration capabilities, and increased the accumulation of DTX in the cancer cells leading to enhanced cell death. We showed that the topical delivery of DTX using DTX-CTs/Gel efficiently slowed down the tumour relapse in post-surgical mouse melanoma and breast tumour models.

Expression and characterization of a novel organic solvent tolerant protease from Bacillus sphaericus DS11

Organic solvent-tolerant proteases have many applications in the synthesis of peptides. In this study, we have developed a low-cost and convenient method to produce highly concentrated organic solvent-tolerant protease. Organic solvent tolerant protease (OSP) gene from Bacillus sphaericus DS11 was cloned and expressed in Bacillus subtilis WB800. The optimum pH of the recombinant protease was 9.0. The optimum temperature of the recombinant protease was 40 °C. The recombinant protease was purified by ethanol with the yield of (87.33%). The yield of OSP enriched by ethanol was higher than that of by Ni-chelating affinity chromatography, which indicated that precipitation of the recombinant OSP with ethanol is a relatively low-cost and fast method for organic solvent -tolerant protease preparation. These results showed that this enzyme could be very useful in different industrial applications.

Biochemical Properties of a Partially Purified Protease from Bacillus sp. CL18 and Its Use to Obtain Bioactive Soy Protein Hydrolysates

Microbial proteases are relevant biocatalysts with diverse applications. Production of protein hydrolysates is recently focused, since they might display biological activities. Therefore, the extracellular protease from Bacillus sp. CL18 was partially purified through ammonium sulfate precipitation (25-50% saturation) and gel filtration chromatography, with a 60.7-fold purification (40,593 U/mg protein) and 21.3% recovery. The partially purified protease (PPP) was characterized as a serine protease, with optimal activity at 51-59 °C and pH 7.4-8.8 and low thermal stability. Thermal inactivation followed first-order kinetics. PPP depended on Ca²⁺ for higher thermal stability, depicted by increases in half-lives (t_1/2), activation energy (E_a), and free energy (ΔG^#) for kinetic inactivation. PPP preferentially hydrolyzed casein > soy protein isolate (SPI) >>> keratinous materials. SPI hydrolysis by PPP was further investigated, and the obtained hydrolysates exhibited increased in vitro bioactivities. Hydrolysates displayed antioxidant capacities through the scavenging of synthetic organic radicals and Fe³⁺-reducing ability. In addition, hydrolysates inhibited the activities of dipeptidyl peptidase IV (DPP IV) and angiotensin-converting enzyme (ACE), suggesting antidiabetic and antihypertensive potentials, respectively. From its biochemical properties, PPP might be used to produce protein hydrolysates with multifunctional bioactivities. Both PPP and SPI hydrolysates can find applications in food biotechnology.

An ionic liquid tolerant cellulase derived from chemically polluted microhabitats and its application in in situ saccharification of rice straw

A cellulase-producing fungus was isolated from chemically polluted microhabitats by [Amim][Cl] enrichment and identified as Aspergillus fumigatus. The maximum activity of the cellulase in 30% (v/v) ionic liquids (ILs) was detected in [Emim][DMP], [Amim][Cl] and [Emim][MA] as 127%, 111% and 109%, respectively, of its activity in buffer, suggesting its superior performance in high concentration ILs. Strikingly, although its initial activity varied in each IL, its half-life was longer in most ILs than in buffer, evidence of a high conformational stability of the enzyme that is essential for maintaining the remaining activity in relevant media. It noteworthy that 1-3M NaCl can activate the cellulase somewhat. More gratifyingly, a compatible IL-cellulase system based on the cellulase was developed, and its use significantly improved the saccharification rate of rice straw from 53% to 88% versus the control, demonstrating its potential for efficient transformation of lignocellulose to glucose in a single-step process.