The stability of structures containing endocytosed horseradish peroxidase in the presence of glycyl-phenylalanine-2-naphthylamide

1984 ◽  
Vol 12 (6) ◽  
pp. 1060-1061 ◽  
Author(s):  
MICHEL JADOT ◽  
SIMONE WATTIAUX-DE CONINCK ◽  
ROBERT WATTIAUX
1967 ◽  
Vol 15 (7) ◽  
pp. 375-380 ◽  
Author(s):  
WERNER STRAUS

Small phagosomes (micropinocytic vesicles and vacuoles) which had taken up injected horseradish peroxidase were identified by staining for peroxidase with benzidine and H2O2. Because of the small size of the granules and the possibility of artifacts, previously described procedures had to be modified in several respects. Prefixation of the tissue by perfusion at 37°C prevented artifacts of diffusion and adsorption of peroxidase. The blue product of the reaction of peroxidase with benzidine in the small phagosomes was preserved and fading to brown was prevented by cooling the tissue section to –10° to –15°C during its processing through polar media. The blue reaction product was stable as soon as the section was transferred to an apolar medium. Small phagosomes were visualized together with lysosomes and phago-lysosomes in the same cells by double staining for acid phosphatase and peroxidase in contrasting colors. The incubation for acid phosphatase was performed at 4°C since low temperature increased the stability of peroxidase in the acid medium. Factors which form the basis for other improvements of the procedure are discussed.


1992 ◽  
Vol 7 (4) ◽  
pp. 299-319 ◽  
Author(s):  
Heinrich Rothert ◽  
Norbert Gebbeken

This paper is mainly focused on the numerical methods which are used to calculate realistically the load-carrying behaviour of reticulated shell structures. It is generally assumed that for an economical analysis, aimed at the saving of material, the material non-linearity has to be taken into consideration if dead loads prevail. For this in the context of finite element analysis the stiffness matrices of elastic and elastic-plastic rod elements are presented. In order to ensure the stability of structures it is indispensable to detect limit loads such as snap-through loads and bifurcation loads. Assuming that snap-through phenomena are quasi static, path-following algorithms can be implemented to trace the load-deflection curves in the postbuckling domain. The testing of the reliability and stability of the algorithms requires a sufficient number of numerical examples. Few will be presented.


Catalysts ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1503
Author(s):  
Qiuyang Wu ◽  
Dong Lu ◽  
Shuming Jin ◽  
Jie Lu ◽  
Fang Wang ◽  
...  

What is known as Furan-2,5-dicarboxylic acid (FDCA) is an attractive compound since it has similar properties to terephthalic acid. Further, 5-hydroxymethylfurfural oxidase (HMFO) is an enzyme, which could convert HMF to FDCA directly. Most wild types of HMFO have low activity on the oxidation of HMF to FDCA. The variant of 8BxHFMO from Methylovorus sp. MP688 was the only reported enzyme that was able to perform FDCA production. However, the stabilization of 8BxHMFO is still not that satisfactory, and further improvement is necessary for the industrial application of the enzyme. In this work, stability-enhanced HMFO from 8BxHFMO was engineered through employing B-factor analysis. The mutation libraries were created based on the NNK degeneracy of residues with the top ten highest B-factor value, and two of the effective mutants were screened out through the high throughput selection with the horseradish peroxidase (HRP)-Tyr assay. The mutants Q319K and N44G show a significantly increased yield of FDCA in the reaction temperature range of 30 to 40 °C. The mutant Q319K shows the best performance at 35 °C with a FDCA yield of 98% (the original 8BxHMFO was only 85%), and a half-life exceeding 72 h. Moreover, molecular dynamic simulation indicates that more hydrogen bonds are formed in the mutants, which improves the stability of the protein structure. The method could enhance the design of more stable biocatalysts; and provides potential for the further optimization and utilization of HMFO in biotechnological processes.


2020 ◽  
Vol 81 (12) ◽  
pp. 2664-2673 ◽  
Author(s):  
Melda Altikatoglu Yapaoz ◽  
Azade Attar

Abstract Horseradish peroxidase (HRP) characteristics were improved by two techniques, Na-alginate entrapment and glutaraldehyde crosslinking prior to alginate entrapment, in order to enhance the stability, functionality and removal of dyes in waste water. Free, entrapped and crosslinked-entrapped enzymes were compared by activity assays, which indicated the optimum temperature is 25 °C and pH 4.0–5.0. Kinetics results showed that alginate entrapment and crosslinking prior to entrapment increased Vmax and did not cause any significant decrease in Km. The thermal resistance of the free enzyme was short-term, zero residual activity after 250 min, while the immobilized enzymes preserved more than 50% of their activity for 5 h at 60 °C. Immobilized HRP was resistant to methanol, ethanol, DMSO and THF. The storage stability of free HRP ended in 35 days whereas entrapped and crosslinked-entrapped HRPs had 87 and 92% residual activity at the 60th day, respectively. HRP was used in the decolorization of azo dye Acid yellow 11 and total decolorization (>99%) was obtained using crosslinked-entrapped HRP. Reusability studies presented the improvement that crosslinked-entrapped HRP reached 74% decolorization after 10 batches. The results demonstrated that the novel immobilized HRP can be used as an effective catalyst for dye degradation of industrial waste effluents.


2015 ◽  
Vol 854 ◽  
pp. 129-139 ◽  
Author(s):  
Griselle Hernández-Cancel ◽  
Damaris Suazo-Dávila ◽  
Johnsue Medina-Guzmán ◽  
María Rosado-González ◽  
Liz M. Díaz-Vázquez ◽  
...  

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