Enzymatic synthesis of activated esters and their subsequent use in enzyme-based peptide synthesis

Techniques for Preparation of Cross-Linked Enzyme Aggregates and Their Applications in Bioconversions

Enzymes are biocatalysts. They are useful in environmentally friendly production processes and have high potential for industrial applications. However, because of problems with operational stability, cost, and catalytic efficiency, many enzymatic processes have limited applications. The use of cross-linked enzyme aggregates (CLEAs) has been introduced as an effective carrier-free immobilization method. This immobilization method is attractive because it is simple and robust, and unpurified enzymes can be used. Coimmobilization of different enzymes can be achieved. CLEAs generally show high catalytic activities, good storage and operational stabilities, and good reusability. In this review, we summarize techniques for the preparation of CLEAs for use as biocatalysts. Some important applications of these techniques in chemical synthesis and environmental applications are also included. CLEAs provide feasible and efficient techniques for improving the properties of immobilized enzymes for use in industrial applications.

Selective and eco-friendly synthesis of lipoaminoacid-based surfactants for food, using immobilized lipase and protease biocatalysts

Lipoaminoacids, as surfactants, are an excellent option for food industry due to the currently trends in consumption of functional and natural ingredients. Synthesis of lauroyl glycine lipoaminoacid was carried out with a lipase from Pseudomonas stutzeri and a protease from Bacillus subtilis, which were immobilized in octyl-glyoxyl silica and glyoxyl-silica supports, respectively, comparing their catalytic performance. The enzymatic selectivity towards the lipoaminoacid instead of the dipeptide glycylglycine and synthesis yield were evaluated with respect to the characteristics of the immobilized biocatalysts and synthesis conditions. Three solvents were tested as reaction media for evaluating the expressed activity, stability and catalytic behavior during synthesis. Results indicate that both enzymes favor the lauroyl glycine synthesis over the peptide synthesis, but the immobilized protease has the best balance between selectivity and yield: 40% yield for lauroyl glycine and less than 5% for dipeptide after 96h of synthesis, at 45°C and acetone as solvent.

Synthesis of glycinamides using protease immobilized magnetic nanoparticles

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Protease producing Bacillus subtilis was isolated from animal slaughter house waste.

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Protease was covalently immobilized on amino-functionalized magnetic nanoparticles (AMNPs).

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To our knowledge, for the first time these magnetic nano biocatalyst was used for the synthesis of series of novel glycinamides.

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Parameters for glycinamides synthesis such as, pH, temperature and time were optimized using Response Surface Methodology.

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Reusability study showed that protease immobilized MNPs retain up to 70% of initial activity after 8th cycles of reuse for the synthesis.

In the present investigation, Bacillus subtilis was isolated from slaughterhouse waste and screened for the production of protease enzyme. The purified protease was successfully immobilized on magnetic nanoparticles (MNPs) and used for the synthesis of series of glycinamides. The binding and thermal stability of protease on MNPs was confirmed by FTIR spectroscopy and TGA analysis. The surface morphology of MNPs before and after protease immobilization was carried out using SEM analysis. XRD pattern revealed no phase change in MNPs after enzyme immobilization. The processing parameters for glycinamides synthesis viz. temperature, pH, and time were optimized using Response Surface Methodology (RSM) by using Design Expert (9.0.6.2). The maximum yield of various amides 2 butyramidoacetic acid (AMD-1,83.4%), 2-benzamidoacetic acid (AMD-2,80.5%) and 2,2′((carboxymethyl) amino)-2-oxoethyl)-2-hydroxysuccinyl)bis(azanediyl))diacetic acid (AMD-3,80.8%) formed was observed at pH-8, 50 °C and 30 min. The synthesized immobilized protease retained 70% of the initial activity even after 8 cycles of reuse.

Amides in Nature and Biocatalysis

Amides are widespread in biologically active compounds with a broad range of applications in biotechnology, agriculture and medicine. Therefore, as alternative to chemical synthesis the biocatalytic amide synthesis is a very interesting field of research. As usual, Nature can serve as guide in the quest for novel biocatalysts. Several mechanisms for carboxylate activation involving mainly acyl-adenylate, acyl-phosphate or acyl-enzyme intermediates have been discovered, but also completely different pathways to amides are found. In addition to ribosomes, selected enzymes of almost all main enzyme classes are able to synthesize amides. In this review we give an overview about amide synthesis in Nature, as well as biotechnological applications of these enzymes. Moreover, several examples of biocatalytic amide synthesis are given.

Recent advances in chemoenzymatic peptide syntheses

Chemoenzymatic peptide synthesis is the hydrolase-catalyzed stereoselective formation of peptide bonds. It is a clean and mild procedure, unlike conventional chemical synthesis, which involves complicated and laborious protection-deprotection procedures and harsh reaction conditions. The chemoenzymatic approach has been utilized for several decades because determining the optimal conditions for conventional synthesis is often time-consuming. The synthesis of poly- and oligopeptides comprising various amino acids longer than a dipeptide continues to pose a challenge owing to the lack of knowledge about enzymatic mechanisms and owing to difficulty in optimizing the pH, temperature, and other reaction conditions. These drawbacks limit the applications of the chemoenzymatic approach. Recently, a variety of enzymes and substrates produced using recombinant techniques, substrate mimetics, and optimal reaction conditions (e.g., frozen aqueous media and ionic liquids) have broadened the scope of chemoenzymatic peptide syntheses. In this review, we highlight the recent advances in the chemoenzymatic syntheses of various peptides and their use in developing new materials and biomedical applications.