Highly active and stable nanobiocatalyst based on in-situ cross-linking of phospholipase D for the synthesis of phosphatidylserine

Hollow Hierarchical Porous and Antihydrolytic Spherical Zeolitic Imidazolate Frameworks for Enzyme Encapsulation and Biocatalysis

The creation of a new metal-organic framework (MOF) with a hollow hierarchical porous structure has gained significant attention in the realm of enzyme immobilization. The present work employed a novel, facile, and effective combinatorial technique to synthesize modified MOF (N-PVP/HZIF-8) with a hierarchically porous core-shell structure, allowing for the preservation of the structural integrity of the encapsulated enzyme molecules. Scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, confocal laser scanning microscopy, and other characterization tools were used to fully explore the changes of morphological structure and surface properties in different stages of the preparation of immobilization enzyme CRL-N-PVP/HZIF-8, thus showing the superiority of N-PVP/HZIF-8 as an enzyme immobilization platform and the logic of the immobilization process on the carrier. Additionally, the maximum enzyme loading was 216.3 mg mL-1, the relative activity of CRL-N-PVP/HZIF-8 increased by 15 times compared with the CRL@ZIF-8 immobilized in situ, and exhibited quite good thermal, chemical, and operational stability. With a maximal conversion of 88.8%, CRL-N-PVP/HZIF-8 demonstrated good catalytic performance in the biosynthesis of phytosterol esters as a proof of concept. It is anticipated that this work will offer fresh concepts from several perspectives for the creation of MOF-based immobilized enzymes for biotechnological uses.

Phospholipids (PLs) know-how: exploring and exploiting phospholipase D for its industrial dissemination

Owing to their numerous nutritional and bioactive functions, phospholipids (PLs), which are major components of biological membranes in all living organisms, have been widely applied as nutraceuticals, food supplements, and cosmetic ingredients. To date, PLs are extracted solely from soybean or egg yolk, despite the diverse market demands and high cost, owing to a tedious and inefficient manufacturing process. A microbial-based manufacturing process, specifically phospholipase D (PLD)-based biocatalysis and biotransformation process for PLs, has the potential to address several challenges associated with the soybean- or egg yolk-based supply chain. However, poor enzyme properties and inefficient microbial expression systems for PLD limit their wide industrial dissemination. Therefore, sourcing new enzyme variants with improved properties and developing advanced PLD expression systems are important. In the present review, we systematically summarize recent achievements and trends in the discovery, their structural properties, catalytic mechanisms, expression strategies for enhancing PLD production, and its multiple applications in the context of PLs. This review is expected to assist researchers to understand current advances in this field and provide insights for further molecular engineering efforts toward PLD-mediated bioprocessing.

Immobilization of phospholipase D on macroporous SiO2/cationic polymer nano-composited support for the highly efficient synthesis of phosphatidylserine

Novel nano-composites were prepared by coating epoxy resin-based cationic polymer in nano-thickness via in-situ curing on the nano-wall of macroporous SiO₂ with pore size of 0.5∼1 μm. By changing the thickness of polymer coating the specific surface area and porosity varied in range of 115∼74 m²/g and 90.4∼83.9 %, respectively. Through ion exchange phospholipase D (PLD, from Streptomyces sp) was efficiently immobilized on the nano-composites as support and the immobilized PLD was applied for the highly efficient synthesis of phosphatidylserine (PS). The loading amount of PLD on the nano-composited support reached to a maximum of 90.2 mg/g_support, 4 times as high as that on the pure macroporous silica. The specific activity of the immobilized PLD reached as high as 16,230 U/g_protein, while that of free PLD was 18,780 U/g_protein. Under a wide range of temperature and pH the stability and activity of the immobilized PLD were greatly improved as compared with the free ones. Under optimized conditions at 45 °C and pH 7.0, the PS yield reached as high as 96.2 % within 40 min. After 28 days storage the immobilized PLD retained 82.2 % of original activity, and after 12 cycling reuses it retained 79.3 % of PS yield, which indicated that the immobilized PLD exhibited good stability.

Phospholipase D encapsulated into metal-surfactant nanocapsules for enhancing biocatalysis in a two-phase system

Methods for enhancing enzyme activities in two-phase systems are getting more attention. Phospholipase D (PLD) was successfully encapsulated into metal-surfactant nanocapsules (MSNCs) using a one-pot self-assembly technique in an aqueous solution. The highest yield for the production of high-value phosphatidylserine (PS) from low-value phosphatidylcholine (PC) in the two-phase system was achieved by encapsulating PLD into MSNCs formed from Ca²⁺ which gave an enzyme activity that was 133.6% of that of free PLD. The PLD@MSNC transformed the two-phase system into an emulsion phase system and improved the organic solvent tolerance, pH and thermal stabilities as well as the storage stability and reusability of the enzyme. Under optimal conditions, PLD@MSNC generated 91.9% PS over 8 h in the two-phase system, while free PLD generated only 77.5%.

PLD@MSNC transforms a two-phase system into an emulsion phase, and enhances transphosphatidylation.