The structures and applications of microbial chondroitin AC lyase.

As an important glycosaminoglycan hydrolase, chondroitin lyases can hydrolyze chondroitin sulfate (CS) and release disaccharides and oligosaccharides. They are further divided into chondroitin AC, ABC, and B lyases according to their spatial structure and substrate specificity. Chondroitin AC lyase can hydrolyze chondroitin sulfate A (CS-A), chondroitin sulfate C (CS-C), and hyaluronic acid (HA), making it an essential biocatalyst for the preparation of low molecular weight chondroitin sulfate, analysis of the structure of the chondroitin sulfate, treatment of spinal cord injury, and purification of heparin. This paper provides an overview of reported chondroitin AC lyases, including their properties and the challenges faced in industrial applications. Up to now, although many attempts have been adopted to improve the enzyme properties, the most important factors are still the low activity and stability. The relations between the stability of the enzyme and the spatial structure were also summarized and discussed. Also perspectives for remodeling the enzymes with protein engineering are included.

Katsuwonus pelamis Peptide and its Complexes Protect Zebrafish and Mice From Hyperuricemia Through Promoting Kidney Excretion of Uric Acid and Inhibiting Liver Xanthine Oxidase Activity.

Katsuwonus pelamis peptide and its complexes have the effect of lowering uric acid (UA)-levels. To identify the effect and possible mechanisms, different concentrations of Katsuwonus pelamis peptide and its complexes were administered to the zebrafish and mice hyperuricemia models, and the UA level was measured. Meanwhile, the hyperuricemic mice were treated orally at 0.83, 1.67, and 5.00 mg/g body weight for 7 days with Katsuwonus pelamis peptide and the complexes groups, separately. The levels of serum UA (SUA), urinary UA (UUA), serum creatinine (SCR), blood urine nitrogen (BUN), and xanthine oxidase (XOD) activities were detected in each group. The results showed that the Katsuwonus pelamis peptide (125 µg/ml) and its complexes (83.3 and 250 µg/ml) effectively reduced UA level in zebrafish with hyperuricemia (p < 0.05). The Katsuwonus pelamis peptide at high concentration (5.00 mg/g) decreased the SUA level, SCR level, BUN level, and hepatic XOD activity, and the complexes (1.67 and 5.00 mg/g) significantly reduced the SUA level and hepatic XOD activity (p < 0.05) in the hyperuricemic mice. In addition, in a hyperuricemic mouse model, the UUA level was increased after treatment with Katsuwonus pelamis peptide and its complexes at high concentrations (p < 0.05). The total therapeutic effects in the Katsuwonus pelamis peptide complex group were better than those in the Katsuwonus pelamis peptide group. Thus, Katsuwonus pelamis peptide and its complexes may possibly be used to prevent hyperuricemia via promoting urate secretion and inhibiting XOD activity production.

One-step selective affinity purification and immobilization of His-tagged enzyme by recyclable magnetic nanoparticles.

The NiFe2O4 magnetic nanoparticles (NF-MNPs) were prepared for one-step selective affinity purification and immobilization of His-tagged recombinant glucose dehydrogenase (GluDH). The prepared nanoparticles were characterized by a Fourier-transform infrared spectrophotometer and microscopy. The immobilization and purification of His-tagged GluDH on NF-MNPs were investigated. The optimal immobilization conditions were obtained that mixed cell lysis and carriers in a ratio of 0.13 in pH 8.0 Tris-HCl buffer at 30℃ and incubated for 2 h. The highest activity recovery and protein bindings were 71.39% and 38.50 µg mg-1 support, respectively. The immobilized GluDH exhibited high thermostability, pH-stability and it can retain more than 65% of the initial enzyme after 10 cycles for the conversion of glucose to gluconolactone. Comparing with a commercial Ni-NTA resin, the NF-MNPs displayed a higher specific affinity with His-tagged recombinant GluDH.

A Novel Chondroitin AC Lyase With Broad Substrate Specificity From Pedobacter rhizosphaerae: Cloning, Expression, and Characterization.

Chondroitin AC lyase (ChSaseAC) is one of the essential polysaccharides lyases in low molecular chondroitin sulfate production. In this work, a novel PrChSaseAC from Pedobacter rhizosphaerae was successfully cloned, expressed in Escherichia coli. After optimizing the induction, the recombinant PrChSaseAC could be expressed efficiently at 0.1 mM IPTG, 25°C, and 12 h induction. Then, it was purified with Ni-NTA affinity chromatography. The characterization of the purified PrChSaseAC showed that it had high specific activity and good storage stability, which would favor the production of low molecular weight chondroitin sulfate. It also displayed activity toward chondroitin sulfate C and hyaluronic acid. PrChSaseAC had the highest activity at pH 7.5, 37°C, 10 mM Ca2+, and 5 mg/ml of chondroitin sulfate A. Molecular docking of substrate and enzyme showed the interactions between the enzyme and substrate; it revealed that the enzyme showed high activity to CS-A and hyaluronic acid, but lower activity to CS-C attributed to the structure of the binding pocket. The high stability and specific activity of the enzyme will benefit the industrial production or clinical treatment.

[Analysis of therapeutic effects of external fixator for the treatment of comminuted fracture of distal radius].

OBJECTIVE: To evaluate the clinical effects of external fixator in treating comminuted fracture of distal radius. METHODS: From Mar.2008 to Dec.2009, 37 patients with comminuted fracture of distal radius were treated with external fixator or assisted with Kirschner wire and T-shape locking compression plate (T-LCP) fixation. There were 14 males and 23 females, ranging in age from 30 to 79 years, with an average of 59.1 years. According to AO typing, type C1 was in 3 cases, type C2 was in 11 cases and type C3 was in 23 cases. Function of wrist joint and X-ray films were observed according to Gratland-Werley system at different months. RESULTS: All patients were followed up from 8 to 24 months with an average of 12 months. All fractures had healing with an average time of 8 weeks. According to Gratland-Werley system, 16 cases obtained excellent result, 17 good, 4 fair, the rate of excellent and good was 89.0%. CONCLUSION: External fixator can obtained satisfactory clinical effect in treating comminuted fracture of distal radius.