Thermostable ficin from jelly fig (Ficus pumila var. awkeotsang) latex: purification, identification and characterization.

BACKGROUND: The achenes/seeds of endemic jelly fig (Ficus pumila var. awkeotsang) fruit have been applied to prepare a traditional beverage in Taiwan. Upon fruit harvest, jelly fig latex exuded from stalks was discarded. Protease activity was monitored in its latex. Proteases capable of hydrolyzing proteins have many application aspects based on diverse characteristics. Commercial plant proteases are frequently from latex. RESULTS: The latex protease of jelly fig, termed FaFicin, was purified to homogeneity with a molecular mass of ~32 kDa on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. According to liquid chromatographic-tandem mass spectrometric analyses, the expected protein band of protease was matched to ficin A, ficin B or chymopapain from common fig or papaya. Iodoacetamide, an inhibitor of cysteine protease, inhibited its protease activity completely. Hence FaFicin was identified as a papain-like cysteine protease (PLCP), exhibiting more than 80% and 70% activity as assayed at pH 5-8 and 40-70 °C, respectively. It maintained ~89% of initial activity after 120 min at 55 °C and pH 7. Moreover, FaFicin could degrade the myosin and actin of meat, and clot milk. CONCLUSION: The ficin FaFicin was obtained, purified and identified as a PLCP member from agricultural waste: jelly fig latex. It possessed activity under a wide range of pH values and temperature, and exhibited excellent thermostability. Based on its initial evaluation as a meat tenderizer and milk clotting reagent, the application of FaFicin was possible, which may extend utilization of jelly fig. © 2022 Society of Chemical Industry.

Green synthesis of nano-silver-titanium nanotube array (Ag/TNA) composite for concurrent ibuprofen degradation and hydrogen generation.

Silver deposited titanate nanotube array composite (Ag/TNA-c) was successfully synthesized using tea leaves and ground coffee as reducing agent for the first time. The synthesis method was effective, eco-friendly, and reproducible in producing quality nano-composite. The Ag/TNA composite was characterized via XPS, SEM, UV-vis, XRD, and electrochemical analyses for chemical and physical properties. Additionally, chlorogenic acid, caffeine, and catechin were selected as reducing agents for purpose of comparison. Results indicated that catechin and chlorogenic acid were the main reducing agents responsible for Ag+ reduction in tea leaves and ground coffee, respectively. The synthesized Ag/TNA-c exhibited the best photocatalytic (PC) performance in terms of photo-current response, EIS, Ibuprofen degradation, and hydrogen generation in a PEC system. Pairing with a Pt cathode, the photoelectrochemical (PEC) system using the synthesized Ag/TNA composite photo-anode, was capable of concurrent anodic oxidation of Ibuprofen and cathodic generation of hydrogen. Deposition of nano-Ag particles on TNA enhanced the concurrent oxidation and reduction reaction in the PEC system. Results of ESR analysis confirmed the role of hydroxyl radical on Ibuprofen degradation over Ag/TNA-c in the PEC system. Mechanism of Ag/TNA PEC system was proposed to illustrate the oxidation and reduction reaction.

Metal carbonyl-gold nanoparticle conjugates for highly sensitive SERS detection of organophosphorus pesticides.

The binding of organometallic osmium carbonyl clusters onto the surface of gold nanoparticles (10OsCO-Au NPs) greatly enhanced the CO stretching vibration signal at ~2100cm-1, which is relatively free from interference due to the absorbance of biomolecules. By utilizing the acetylcholinesterase (AChE) mediated hydrolysis of acetylthiocholine to thiocholine where the activity of AChE is inhibited by the presence of organophosphate pesticides (OPPs), the subsequent thiocholine-induced aggregation of 10OsCO-Au NPs can be monitored by the change in color of the NPs solution and the variation in intensity of the SERS CO signal. The change in color offers a fast pre-screening method, whereas monitoring via SERS is used for greater accuracy and lower limit of detection (0.1 ppb) for quantitative detection. Its potential as a quick and accurate method of OPPs monitoring in consumer products was demonstrated in the detection of OPPs in real spiked samples such as beer.