A new l-arabinose isomerase with copper ion tolerance is suitable for creating protein–inorganic hybrid nanoflowers with enhanced enzyme activity and stability

Abstract

Protein-inorganic hybrid nanoflowers were prepared using Cu 2+ , PBS buffer, and a copper ion tolerant L-arabinose isomerase that was derived from Paenibacillus polymyxa (PPAI). The expensive rare sugar L-ribulose or D-tagatose was prepared utilizing these nanoflowers with L-arabinose or D-galactose as the substrate, respectively. The PPAI hybrid nanoflowers showed better enzyme stabilities in both thermal and acidic conditions. Meanwhile, long term batch production was successful showing high stability using these hybrid nanoflowers, which achieved a conversion rate of 61.8% from L-arabinose to L-ribulose.L-Ribose is an important pharmaceutical intermediate for the production of L-form sugar based antivirus drugs including those targeting human immunodeciency virus (HIV), hepatitis B/C virus (HBV/HCV), and human cytomegalovirus (HCMV). 1-3 L-Ribose does not exist in nature and it can only be obtained through chemical synthesis. However, its synthetic route is complicated, which composed of 5-6 steps and the nal yield is low. 1,2 Recently, biological production of L-ribose was established using a two-step reaction: L-arabinose, as the starting raw material, was rstly converted into its ketose isomer L-ribulose by L-arabinose isomerase (namely AI, EC 5.3.1.4), and then isomerized into L-ribose by mannose-6-phosphate isomerase (namely MPI, EC 5.3.1.8). 4,5 This method achieved a conversion rate of 23.6% from L-arabinose to L-ribose and a volumetric productivity of 39.3 g L À1 h À1 . 5 Considering that liquid L-arabinose was easily extracted from corncob bres hydrolysates, this method is economical. On the other hand, AI was widely

Electrochemically Stable and Catalytically Active Coatings Based on Self-Assembly of Protein-Inorganic Nanoflowers on Plasma-Electrolyzed Platform

“…On the other hand, an increase in BSA concentration promotes the number of nucleation sites, resulting in a slight decrease in the average size of NCs. In the present study, the influence of protein concentration on the morphology of the NCs shows a stark contrast with that in previous reports on hybrid nanoflowers fabricated in free solutions. ,− Without a solid platform, it was reported that a high protein concentration inhibited the “blooming” of the nanoflowers, and therefore, a closed arrangement of nanopetals was likely to occur. With the present inorganic platforms, the nanoflowers shape remains similar regardless of the protein concentration.…”

“…Thus, P1 triggers a large number of NCs in the resultant flower-bed layer (PNC1) due to its large population of micropores, while those fabricated with P2 and P3 (PNC2 and PNC3, respectively) show a smaller number of NCs that is relatively proportional to their porosity. In addition, the facilitation of the inorganic platforms accelerated the self-assembly process from 72 h in previous studies ,− to 48 h in this work.…”

Protein–inorganic hybrid system for efficient his-tagged enzymes immobilization and its application in l-xylulose production

“…Advantages of protein-inorganic hybrid biocatalysts for conversion of carbohydrates are mild synthesis conditions and high selectivity for desired products. 46,47 However, the requirement of pure enzymes for the synthesis of hybrid biocatalysts is a disadvantage. 47…”

“…46,47 However, the requirement of pure enzymes for the synthesis of hybrid biocatalysts is a disadvantage. 47…”

Imidazole‐Grafted Nanogels for the Fabrication of Organic–Inorganic Protein Hybrids

“…This circumstance can be prejudicial, since copper has been identified as an efficient inhibitor of the activity of a large variety of enzymes . In fact, in their attempt to create l ‐arabinose isomerase nanoflowers, Xu et al were forced to use a copper‐tolerant variant in order to avoid detrimental effects on the enzyme performance . Moreover, only few examples of nanoflowers have been reported combining phosphate salts and specific enzymes with further divalent cations (e.g., Ca 2+ , Co 2+ , Zn 2+ ) .…”