Engineering of a CPC acylase using a facile pH indicator assay

Optimization of cephalosporin C acylase immobilization using crosslinked enzyme aggregates technique

Cephalosporin C acylase (CCA) is an essential enzyme for the one-step conversion of cephalosporin C into 7-aminocephalosporanic acid (7-ACA), an intermediate compound used to synthesize various semi-synthetic cephalosporin antibiotics. The industrial process prefers to use enzymes in immobilized form rather than soluble. A crosslinked enzyme aggregate (CLEAs) is a potential matrix-less enzyme immobilization technique to produce stable immobilized enzymes with high activity and low production costs. This study aimed to optimize the CCA immobilization using the CLEAs technique with Chitosan as a co-aggregate. The CCA lysate was obtained from harvesting CCA fermentation broth using a mutant strain of Escherichia coli through cell separation and lysis steps. Partially purified CCA by ammonium sulfate addition was conducted to obtain an active fraction of 20-60% saturation, followed by co-aggregation with Chitosan to form physical CCA aggregates. The aggregates were then immobilized by a crosslinking technique using glutaraldehyde to form CLEAs-CCA. Optimization of the immobilization process was carried out by Response Surface Methodology in three steps, (i) screening of the influencing factors, (ii) determining the level of the significant factors, and (iii) optimizing the immobilization condition. The CLEAs-CCA activity was used as a response parameter. Under optimum conditions, CLEAs-CCA activity obtained was 85.91 Ug-1.

Strategy for the Biosynthesis of Short Oligopeptides: Green and Sustainable Chemistry

Short oligopeptides are some of the most promising and functionally important amide bond-containing components, with widespread applications. Biosynthesis of these oligopeptides may potentially become the ultimate strategy because it has better cost efficiency and environmental-friendliness than conventional solid phase peptide synthesis and chemo-enzymatic synthesis. To successfully apply this strategy for the biosynthesis of structurally diverse amide bond-containing components, the identification and selection of specific biocatalysts is extremely important. Given that perspective, this review focuses on the current knowledge about the typical enzymes that might be potentially used for the synthesis of short oligopeptides. Moreover, novel enzymatic methods of producing desired peptides via metabolic engineering are highlighted. It is believed that this review will be helpful for technological innovation in the production of desired peptides.

Comparison of broad-scope assays of nucleotide sugar-dependent glycosyltransferases

Glycosyltransferases (GTs) are abundant in nature and diverse in their range of substrates. Application of GTs is, however, often complicated by their narrow substrate specificity. GTs with tailored specificities are highly demanded for targeted glycosylation reactions. Engineering of such GTs is, however, restricted by lack of practical and broad-scope assays currently available. Here we present an improvement of an inexpensive and simple assay that relies on the enzymatic detection of inorganic phosphate cleaved from nucleoside phosphate products released in GT reactions. This phosphatase-coupled assay (PCA) is compared with other GT assays: a pH shift assay and a commercially available immunoassay in Escherichia coli cell-free extract (CE). Furthermore, we probe PCA with three GTs with different specificities. Our results demonstrate that PCA is a versatile and apparently general GT assay with a detection limit as low as 1 mU. The detection limit of the pH shift assay is roughly 4 times higher. The immunoassay, by contrast, detected only nucleoside diphosphates (NDPs) but had the lowest detection limit. Compared with these assays, PCA showed superior robustness and, therefore, appears to be a suitable general screening assay for nucleotide sugar-dependent GTs.