Enhancing thermostability of xylanase from rumen microbiota by molecular cyclization / 生物工程学报

The capacity for thermal tolerance is critical for industrial enzyme. In the past decade, great efforts have been made to endow wild-type enzymes with higher catalytic activity or thermostability using gene engineering and protein engineering strategies. In this study, a recently developed SpyTag/SpyCatcher system, mediated by isopeptide bond-ligation, was used to modify a rumen microbiota-derived xylanase XYN11-6 as cyclized and stable enzyme C-XYN11-6. After incubation at 60, 70 or 80 ℃ for 10 min, the residual activities of C-XYN11-6 were 81.53%, 73.98% or 64.41%, which were 1.48, 2.92 or 3.98-fold of linear enzyme L-XYN11-6, respectively. After exposure to 60-90°C for 10 min, the C-XYN11-6 remained as soluble in suspension, while L-XYN11-6 showed severely aggregation. Intrinsic and 8-anilino-1-naphthalenesulfonic acid (ANS)-binding fluorescence analysis revealed that C-XYN11-6 was more capable of maintaining its conformation during heat challenge, compared with L-XYN11-6. Interestingly, molecular cyclization also conferred C-XYN11-6 with improved resilience to 0.1-50 mmol/L Ca²⁺ or 0.1 mmol/L Cu²⁺ treatment. In summary, we generated a thermal- and ion-stable cyclized enzyme using SpyTag/SpyCatcher system, which will be of particular interest in engineering of enzymes for industrial application.

Advances in isopeptide bond-mediated molecular superglue / 生物工程学报

Isopeptide bond-mediated molecular superglue is the irreversible covalent bond spontaneously formed by the side chains of lysine (Lys) and asparagine/aspartic acid (Asn/Asp) residues. The peptide-peptide interaction is specific, stable, and can be achieved quickly without any particular physicochemical factor. In the light of recent progress by domestic and foreign researchers, here we summarize the origin, assembly system and mechanism of isopeptide bond reaction, as well as the molecular cyclization and protein topological structure mediated by it. The prospect for its application in synthetic vaccine, hydrogel and bacterial nanobiological reactor is further discussed.

Progress in lytic polysaccharide monooxygenase / 生物工程学报

Lignocellulose is the most abundant renewable biomass resource. Enzymatic breakdown of lignocellulose into oligosaccharides or monosaccharides is the key to exploit lignocellulosic biomass. However, traditional glycoside hydrolases are insufficient to degrade lignocellulose. The emergence of lytic polysaccharide monooxygenase, a novel enzyme for lignocellulose degradation, has enriched the deconstruction schema and accelerated the enzymatic conversion of polysaccharides, by introducing new chain breaks that allow hydrolases to initiate further degradation. Here, we review the discovery, classification and catalytic mechanism of the enzyme, as well as the methods for assaying its activity. The prospect for its application in feed additive, functional food and biofuel development is further discussed.

Clinical diagnosis and treatment of 60 children with henoch-schonlein purpura / 中国基层医药

Objective To analyze the clinical data of henoch-schonlein purpura(HSP)in children and to conclude the clinieal featrues of HSP.Methods The clinieal features of 60 children with HSP were analyzed.Results(1)The age of onset of all the 60 children with HSP was from 3 to 14 yearn old,especially from 5 to 10 years and the female patients were more than the male patients(the ratewas 2:1).Of the 60 children,they developed HSP in the four seasons,especially in the spring and winter;most of the HSP patients revealed evident predisposing factors,mainly upper respiratory infection.(2)All the patients had typical purpura.80% had typical purpura as the presenting contancous sign.The distribution of rash in the lower extremitiees,buttock upper extremities and face was 100%,30%,13% and 7%.30% occurre,repeatedly.(3)Gastrointestinal involvement and arthritis occurred rate is 47% and 60%,respectively.Of all the patients,13% devdoped HSP nephritis manifested as isolated hematuria and/or protcinuria.Conclusion HSP has its own clinical and episodic features.It is not difficult to diagnose the typical case.HSPN is its serious syndrome,it should be long-term foflow-up of kidney conditions.

Bearing capacity of a modified U-shaped plate / 中国组织工程研究

BACKGROUND: Authors' previous studies showed that U-shaped plate could give continuously pressure to broken ends of fractured bone and make the fractured region in an optimal environment and promote union of fracture.OBJECTIVE: To discuss the loading ability of modified U-shaped plate.DESIGN, TIME AND SETTING: The single sample experiment was performed at the Laboratory of Materials Mechanics, Central South University from December 1990 to April 2001.MATERIALS: Plain bone plate is provided by Jiangsu Jinlu, China. AO plate and dynamic compression plate are purchased from MATHYS, Switzerland. U-shaped plate is a modified plate with a U-shaped arm in the middle of a common plate (Patent number 012497304).METHODS: We measured the mechanics of experimental mode to understand the compressing and distorting ability, m test theoretic calculation and to compare with common plate, AO plate and dynamic compression plate.MAIN OUTCOME MEASURES: Bending ability and distorting ability.RESULTS: Compared with the same usage of AO-Plate and dynamic compression plate at sagittal face, the bending ability of U-shaped plate could increase respectively by 107.5% and 21.5%, and the distorting ability increase respectively by 406% and 58%. Distorting ability increased by 31.9%, compared with limited contact dynamic compress plate (LC-DCP).CONCLUSION: Modified U-shaped plate is an eligible plate of enough strength and rigidity, compared with common AO plate and compress plate.

Early clinical analysis of infants with cerebral palsy / 中国基层医药

Objective To explore early clinical diagnosis of infant with cerebral palsy(CP). Methods Early diagnosis of cerebral palsy information abroad was referenced. DDST scale screening, newborn NBAS inspection stan-dards, VOJTA postural reflex and the nervous system reflective were used to evaluate the cerebral palsy. Results 90 cases CP of which 63 eases spastie. Xu mobile hand-foot-15 cases, 12 cases of mixed type. Conclusion Standardized,quantitative indicators,only workable and easy to use.

Clinical observation of ganciclovir treatment for the young child viral encephalitis / 中国基层医药

Objective To observe effect of ganciclovir on the treatment of the young child viral encephalitis. Methods 68 cases of viral encephalitis were randomly divided into treatment group(45 cases) and the control group (23 cases), the two groups of children with clinical manifestations and treatment effects were observed. Results Headache, vomiting, convulsions symptoms and the resumption of the time was obviously shorter in treatment group than that of the control group, fever symptoms persisted despite the shortened time, but the difference was not statis- tically significant. Conclusion Ganciclovir in children with viral encephalitis have significant effect.