Two Kinesins from Arabidopsis, KatB and KatC, Have a Second Microtubule-binding Site in the Tail Domain

Jiang, Shiling,Li, Ming,Xu, Tao,Ren, Dongtao,Liu, Guoqin Korean Society for Biochemistry and Molecular Biol 2007 Journal of biochemistry and molecular biology Vol.40 No.1

Kinesins, as a kind of microtubule-based motor proteins, have a conserved microtubule-binding site in their motor domain. Here we report that two homologous kinesins in Arabidopsis thaliana, KatB and KatC, contain a second microtubule-binding site in their tail domains. The prokaryotic-expressed N-terminal tail domain of the KatC heavy chain can bind to microtubules in an ATP-insensitive manner. To identify the precise region responsible for the binding, a serious of truncated KatC cDNAs encoding KatC N-terminal regions in different lengths, KatC1-128, KatC1-86, KatC1-73 and KatC1-63, fused to Histidine-tags, were expressed in E. coli and affinity-purified. Microtubule cosedimentation assays show that the site at amino acid residues 74-86 in KatC is important for microtubule-binding. By similarity, we obtained three different lengths of KatB N-terminal regions, KatB1-384, KatB1-77, and KatB1-63, and analyzed their microtubule-binding ability. Cosedimentation assays indicate that the KatB tail domain can also bind to microtubules at the same site as and in a similar manner to KatC. Fluorescence microscopic observations show that the microtubule-binding site at the tail domain of KatB or KatC can induce microtubules bundling only when the stalk domain is present. Through pull-down assays, we show that KatB1-385 and KatC1-394 are able to interact specifically with themselves and with each other in vitro. These findings are significant for identifying a previously uncharacterized microtubule-binding site in the two kinesin proteins, KatB and KatC, and the functional relations between them.

Proteolytic effect of starter culture during ripening of smoked horse sausage

Lu Shiling,Han Xianna,Yang yanbin,Li Baokun,Xu Chengjian,Wang Qingling 한국식품과학회 2017 Food Science and Biotechnology Vol.26 No.5

In this study, we assessed the effect of bacterial and endogenous enzymes on the proteolysis of smoked horse sausage. Commercial starter culture (Staphylococcus xylosus + Lactobacillus sakei) was used in smoked horse sausage. Cathepsin B + L and cathepsin B activities, microbiological growth, pH, and water activity (aw) were measured. Based on PCR-DGGE fingerprint analyses, the starter culture inhibited endogenous bacterial growth. During ripening, the residual activity of cathepsin B + L and cathepsin B was higher in batch C (control) than in batch S (containing starter cultures). The starter and endogenous enzymes promote the degradation of sarcoplasmic and myofibrillar proteins; however, the degradation of these proteins was higher in batch S than in batch C. Therefore, bacterial enzymes played a major role in the degradation of proteins during the ripening of smoked horse sausage.

Effect of glycidyl methacrylate-grafted poly(ethylene octene) on the compatibility in PLA/PBAT blends and films

Ye Zhang,Shiling Jia,Pan Hongwei,Lijuan Wang,Junjia Bian,Yang Guan,Bohao Li,Huiliang Zhang,Huili Yang,Lisong Dong 한국화학공학회 2021 Korean Journal of Chemical Engineering Vol.38 No.8

A series of poly(lactic acid) (PLA), poly(butylene adipate-co-terephthalate) (PBAT) and glycidyl methacrylate- grafted poly(ethylene octene) (GPOE) blends and films with different GPOE content were prepared by melt blending and blowing film technique. The effect of GPOE on the rheological behavior, melt strength, crystallization behavior, crystallization morphology, miscibility, mechanical property, phase morphology, thermal stability and water vapor permeability were studied. The addition of GPOE improved melt rheological properties. Results of DSC showed that addition of GPOE encouraged the mobility of PLA molecular chains and enhanced crystalline ability. POM observations revealed that the addition of GPOE made the density of spherulite nucleation increase and the size of crystalline particles decrease. From DMA and SEM analysis, it was demonstrated that PLA/PBAT blend was an immiscible system and GPOE in the blend could improve compatibility between PLA and PBAT. Results of mechanical test showed that the PLA/PBAT/GPOE blends and films obtained had excellent mechanical properties. The elongation at break of 50/30/ 20 w/w/w PLA/PBAT/GPOE blend (477%) was higher by about 2.2 times than that of 70/30/0 w/w/w PLA/PBAT/ GPOE blend (220%). The tensile strength of all the PLA/PBAT/GPOE blends exceeded 31 MPa. The tensile strength reached 32.9MPa (MD) and 22.5MPa (TD), the elongation at break exceeded 210% and tear strength exceeded 140 kN/m for 50/30/20 w/w/w PLA/PBAT/GPOE film. With increasing GPOE content, thermal stability and water vapor barrier property also improved.

Construction of g/C3N4-ZnO composites with enhanced visible-light photocatalytic activity for degradation of amoxicillin

Shuhan Sun,Shiling Li,Yibing Hao,Xiao Yang,Xiaomin Dou 한국화학공학회 2022 Korean Journal of Chemical Engineering Vol.39 No.12

g/C3N4-ZnO composite catalysts were synthesized through surface hybridization of the delocalized conjugated- structure of g/C3N4 with the closely contacted surface of ZnO via a successive and simultaneous calcinationprocedure, and two kinds of photocatalysts, g/C3N4-ZnO1 and g/C3N4-ZnO2, were obtained. Heterojunctions wereformed between the two components, which promote the separation of photogenerated carriers efficiently, and thenenhanced the degradation of 100mg/L of AMX. The degradation rate of g/C3N4-ZnO1 was 1.54, 11.33, and 2.52-foldthat of g/C3N4-ZnO2, g/C3N4, and ZnO, respectively, at a 3.5-h reaction period, with the dosage of 0.3 g/L, and solutionpH at 7.0±0.2. The recycle and reuse ability was excellent and 90.5% of AMX mitigation was achieved in the fifthcycle. For g/C3N4-ZnO1, electrons migrated from the conduction band of g/C3N4 to that of ZnO via the heterojunction. ·OH and h+ were the main active species for AMX degradation, compared to ·O2 dominated for g/C3N4. Twelveintermediate products were identified, and two degradation pathways were inferred for g/C3N4-ZnO1 and g/C3N4-ZnO2, respectively. Finally, transformation products without lactam rings were achieved, which lost most of the antibacterialpotencies, and the ecotoxicity was also dramatically decreased as indicated by the ECOSAR program.

Constructing foldable cylindrical surfaces via unfolded waterbomb origami units

Zhao Yan,Wei Yinglei,Jia Yiyang,Li Shiling,Zhang Mingyue,Zeng Lanling,Yang Yang,Mitani Jun 한국CDE학회 2022 Journal of computational design and engineering Vol.9 No.4

Origami tessellations have shown the potential to be utilized for approximating curved target surfaces by folding a set of elemental units. As those units are in partially folded states, the origami approximation captures the outline of the target while demonstrating a corrugated surface. In this paper, we focus on the cylindrical surface and propose a method for constructing its discrete version via square or rectangular units with crease patterns inspired by the waterbomb tessellation. We unify the unit size through optimization to realize cost-efficient constructions. Three-dimensional curved structures are deployed by folding collinear creases between adjacent rows of units and the other creases in each row are remained unfolded. The deployed structure can still be folded to a compact state by folding all creases. To flexibly approximate the outline of the target surface, we analyse relationships between the width and height of the rectangular unit and utilize variations of the waterbomb tessellation to control the region of the origami structure when fully folded. The proposed method provides a novel solution to the so-called inverse-origami-design problem for generating foldable cylindrical surfaces using unfolded waterbomb origami units.

Craze density based fatigue-damage analysis in polyethylene methacrylate

Zongzhan Gao,Wei Liu,Qinghai Li,Shiling Liu,Zhufeng Yue,Baoxing Xu 대한기계학회 2019 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.33 No.1

The S-N curve, also known as the Wöhler curve, is well acknowledged and widely used in the prediction of fatigue life of engineering materials. In this study, we present a craze density model, as an alternative approach, to predict the fatigue life of polymer materialpolyethylene methacrylate (PMMA). Our experiments show that craze grows rapidly with the increase of fatigue loadings after their initiation on the surface of PMMA till to the failure of specimens. Dynamic measurements indicate that the growth rate of craze density reaches a stable stage after a rapid accumulation at the beginning, and dominates the fatigue life of PMMA. Both initiation time of crazing and deformation energy of PMMA are probed through the recorded fatigue stress-strain curves and the optical microscope (OM) observations on crazing evolutions. The critical growth rate of the craze density is correlated with the yield stress and strain of PMMA at quasi-static loadings. On the basis of the craze density, an experimental model is established to predict the fatigue damage and life of PMMA. The predication shows good agreement with that from both experiments and traditional S-N curves in a broad range of fatigue loadings.