Role of His-His interaction in Ser474-His475-Tyr476 sequence of chondroitinase ABC I in the enzyme activity and stability

Improvement of thermal-stability of chondroitinase ABCI immobilized on graphene oxide for the repair of spinal cord injury

Spinal cord injury healing has been shown to be aided by chondroitinase ABC I (cABCI) treatment. The transport of cABCI to target tissues is complicated by the enzyme's thermal instability; however, cABCI may be immobilized on nanosheets to boost stability and improve delivery efficiency. This investigation's goal was to assess the immobilization of cABC I on graphene oxide (GO). for this purpose, GO was produced from graphene using a modified version of Hummer's process. the immobilization of cABC I on GO was examined using SEM, XRD, and FTIR. The enzymatic activity of cABC I was evaluated in relation to substrate concentration. The enzyme was then surface-adsorption immobilized on GO, and its thermal stability was examined. As compared to the free enzyme, the results showed that the immobilized enzyme had a greater Km and a lower Vmax value. The stability of the enzyme was greatly improved by immobilization at 20, 4, 25, and 37 °C. For example, at 37 °C, the free enzyme retained 5% of its activity after 100 min, while the immobilized one retained 30% of its initial activity. The results showed, As a suitable surface for immobilizing cABC I, GO nano sheets boost the enzyme's stability, improving its capability to support axonal regeneration after CNC damage and guard against fast degradation.

Engineering a thermostable chondroitinase for production of specifically distributed low-molecular-weight chondroitin sulfate

Chondroitinase ABC I (csABC I) has attracted intensive attention because of its great potential in heparin refining and the enzymatic preparation of low-molecular-weight chondroitin sulfate (LMW-CS). However, low thermal resistance (<30℃) restricts its applications. Herein, structure-guided and sequence-assisted combinatorial engineering approaches were applied to improve the thermal resistance of Proteus vulgaris csABC I. By integrating the deletion of the flexible fragment R166-L170 at the N-terminal domain and the mutation of E694P at the C-terminal domain, variant NΔ5/E694P exhibited 247-fold improvement of its half-life at 37℃ and a 2.3-fold increase in the specific activity. Through batch fermentation in a 3-L fermenter, the expression of variant NΔ5/E694P in an Escherichia coli host reached 1.7 g L^-1 with the activity of 1.0 × 10⁵ U L^-1 . Finally, the enzymatic approach for the preparation of LMW-CS was established. By modulating enzyme concentration and controlling depolymerization time, specifically distributed LMW-CS (7000, 3400, and 1900 Da) with low polydispersity was produced, demonstrating the applicability of these processes for the industrial production of LMW-CS in a more environmentally friendly way.

Bioinformatics and experimental studies on the structural roles of a surface-exposed α-helix at the C-terminal domain of Chondroitinase ABC I

A series of single and double mutants generated on residues of a surfaced-exposed helix at the C-terminal domain of chondroitinase ABC I (cABC I) from proteus vulgaris. M886A, G887E, and their respective double mutant, MA/GE were inspired by the sequence of a similar helix segment in 30S ribosomal protein S1. Additionally, M889I, Q891K, and the corresponding double mutant, MI/QK, were made regarding the sequence of a similar helix in chondroitin lyase from Proteus mirabilis. Circular dichroism spectra in the far-UV region, demonstrate that the ordered structure of wild-type (WT), and double mutants are the same; however, the helicity of the ordered structures in MI/QK is higher than that of the WT enzyme. When compared with the single mutants, the double mutants showed higher activity, and that the activity of MI/QK is higher than that of the WT enzyme. Heat-induced denaturation experiments showed that the stability of the tertiary structure of double mutants at moderate temperatures is higher compared with the WT, and single mutants. It concluded that this helix can be considered as one of the hot spots region that can be more manipulated to obtain improved variants of cABC I.

Reengineering biocatalysts: Computational redesign of chondroitinase ABC improves efficacy and stability

Maintaining biocatalyst stability and activity is a critical challenge. Chondroitinase ABC (ChABC) has shown promise in central nervous system (CNS) regeneration, yet its therapeutic utility is severely limited by instability. We computationally reengineered ChABC by introducing 37, 55, and 92 amino acid changes using consensus design and forcefield-based optimization. All mutants were more stable than wild-type ChABC with increased aggregation temperatures between 4° and 8°C. Only ChABC with 37 mutations (ChABC-37) was more active and had a 6.5 times greater half-life than wild-type ChABC, increasing to 106 hours (4.4 days) from only 16.8 hours. ChABC-37, expressed as a fusion protein with Src homology 3 (ChABC-37-SH3), was active for 7 days when released from a hydrogel modified with SH3-binding peptides. This study demonstrates the broad opportunity to improve biocatalysts through computational engineering and sets the stage for future testing of this substantially improved protein in the treatment of debilitating CNS injuries.