PHYSICOCHEMICAL PROPERTIES AND FUNCTION OF PLANT POLYPHENOL OXIDASE: A REVIEW

2003 ◽  
Vol 27 (5) ◽  
pp. 361-422 ◽  
Author(s):  
RUHIYE YORUK ◽  
MAURICE R. MARSHALL
Keyword(s):  
Physicochemical Properties ◽  
Polyphenol Oxidase ◽  
Plant Polyphenol ◽  
And Function

scholarly journals Bioelectrocatalytic hydrogels from electron-conducting metallopolypeptides coassembled with bifunctional enzymatic building blocks

2008 ◽  
Vol 105 (40) ◽  
pp. 15275-15280 ◽  
Author(s):  
Ian R. Wheeldon ◽  
Joshua W. Gallaway ◽  
Scott Calabrese Barton ◽  
Scott Banta
Keyword(s):  
Polyphenol Oxidase ◽  
Building Block ◽  
Leucine Zipper ◽  
Electrical Contact ◽  
Building Blocks ◽  
Coiled Coils ◽  
Biofuel Cell ◽  
Random Coil ◽  
Catalytic Current ◽  
And Function

Here, we present two bifunctional protein building blocks that coassemble to form a bioelectrocatalytic hydrogel that catalyzes the reduction of dioxygen to water. One building block, a metallopolypeptide based on a previously designed triblock polypeptide, is electron-conducting. A second building block is a chimera of artificial α-helical leucine zipper and random coil domains fused to a polyphenol oxidase, small laccase (SLAC). The metallopolypeptide has a helix–random-helix secondary structure and forms a hydrogel via tetrameric coiled coils. The helical and random domains are identical to those fused to the polyphenol oxidase. Electron-conducting functionality is derived from the divalent attachment of an osmium bis-bipyrdine complex to histidine residues within the peptide. Attachment of the osmium moiety is demonstrated by mass spectroscopy (MS-MALDI-TOF) and cyclic voltammetry. The structure and function of the α-helical domains are confirmed by circular dichroism spectroscopy and by rheological measurements. The metallopolypeptide shows the ability to make electrical contact to a solid-state electrode and to the redox centers of modified SLAC. Neat samples of the modified SLAC form hydrogels, indicating that the fused α-helical domain functions as a physical cross-linker. The fusion does not disrupt dimer formation, a necessity for catalytic activity. Mixtures of the two building blocks coassemble to form a continuous supramolecular hydrogel that, when polarized, generates a catalytic current in the presence of oxygen. The specific application of the system is a biofuel cell cathode, but this protein-engineering approach to advanced functional hydrogel design is general and broadly applicable to biocatalytic, biosensing, and tissue-engineering applications.

scholarly journals Impact of Biochar on Physicochemical Properties of Haplic Luvisol Soil under Different Land Use: A Plot Experiment

Agronomy ◽  
2019 ◽  
Vol 9 (9) ◽  
pp. 531 ◽  
Author(s):  
Marta Cybulak ◽  
Zofia Sokołowska ◽  
Patrycja Boguta
Keyword(s):  
Physicochemical Properties ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Physicochemical Characterization ◽  
Organic Carbon Content ◽  
Limited Information ◽  
Opposite Trend ◽  
And Function ◽  
Positive Effect

There is limited information regarding the effect of biochar (BioC) on improving the fertility of degraded soils (fallow and grassland), particularly with respect to changes with time. The objective of the study was to evaluate, in a three-year field experiment, the influence of BioC on the physicochemical properties of Haplic Luvisol. BioC, obtained via wood waste pyrolysis at 650 °C, was applied to the soil of subplots under fallow and grassland at rates of 0, 1, 2, and 3 kg·m−2. Soil samples were collected eight times, from 2013 to 2015. Physicochemical characterization was performed for soil and BioC by analyzing density, pH, surface charge, as well as ash and organic carbon content. BioC’s influence on the physicochemical properties of degraded soils was determined by analyzing the changes in pH, specific surface area, radius, and volume of the micropore. The addition of BioC affected analyzed soils to varying degrees. In the case of the fallow, a positive effect on changes in these parameters was observed, particularly at the highest biochar dose and for the last year of the experiment. However, for the grassland, in most cases we observed the opposite trend—for example, pH and specific surface area values decreased with increasing biochar dose. We believe that it is necessary to examine how BioC affects sorption properties of organic matter of fallow and grassland soils, as well as the BioC’s influence on humic acids of these soils as a function on BioC dose and function of time.

The effect of elongation of a peptide substituent with ArgSer motif on the antimicrobial properties of hemin derivatives

2018 ◽  
Vol 22 (12) ◽  
pp. 1060-1071
Author(s):  
Sergey V. Blagodarov ◽  
Galina A. Zheltukhina ◽  
Sergey V. Yeremin ◽  
Ekaterina S. Babicheva ◽  
Elena P. Mirchink ◽  
...  
Keyword(s):  
Physicochemical Properties ◽  
Aqueous Solutions ◽  
Water Solubility ◽  
Antimicrobial Properties ◽  
Correlation Spectroscopy ◽  
Nonmonotonic Dependence ◽  
Biological Potency ◽  
And Function ◽  
Antibacterial And Antifungal ◽  
The Relationship

The natural metalloporphyrin hemin possesses a number of properties that determine its attractiveness as a basis for creating potential medicines. The development of research in this area is restrained by hemin’s pronounced toxicity, mainly in relation to normal red blood cells, and also by its water insolubility. We previously synthesized amino acid and peptide hemin derivatives with sufficient water solubility and in some cases high antimicrobial (antibacterial and antifungal) potency [1, 2]. In order to establish the relationship between structure and function, this paper studies the peptide substituent in hemin derivatives (HD) elongated by multiplying the -ArgSer- motif and its effect on the biological and physicochemical properties of their aqueous solutions. A nonlinear nonmonotonic dependence of their physicochemical properties and biological potency on the HD concentration and the length of peptide substituent was revealed based on calculations of hydrophilic properties of substituents in HD and a study by electron and laser correlation spectroscopy of their properties in aqueous solutions.

Correlations among sequence, physicochemical properties and function in peptide toxins

Toxicon ◽  
2020 ◽  
Vol 177 ◽  
pp. S17
Author(s):  
Raymond S. Norton ◽  
Michela L. Mitchell ◽  
Thomas Shafee
Keyword(s):  
Physicochemical Properties ◽  
Peptide Toxins ◽  
And Function

scholarly journals PEG-Mediated Synthesis of Highly Dispersive Multifunctional Superparamagnetic Nanoparticles: Their Physicochemical Properties and Function In Vivo

ACS Nano ◽  
2010 ◽  
Vol 4 (4) ◽  
pp. 2402-2410 ◽  
Author(s):  
Conroy Sun ◽  
Kim Du ◽  
Chen Fang ◽  
Narayan Bhattarai ◽  
Omid Veiseh ◽  
...  
Keyword(s):  
Physicochemical Properties ◽  
Superparamagnetic Nanoparticles ◽  
And Function

scholarly journals Soil Bacterial Community Responds to Land-Use Change in Riparian Ecosystems

Forests ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 157
Author(s):  
Vicky Waymouth ◽  
Rebecca E. Miller ◽  
Sabine Kasel ◽  
Fiona Ede ◽  
Andrew Bissett ◽  
...  
Keyword(s):  
Land Use ◽  
Bacterial Community ◽  
Physicochemical Properties ◽  
Riparian Forest ◽  
Soil Depth ◽  
Riparian Forests ◽  
Functional Composition ◽  
Bacterial Taxonomy ◽  
Soil Bacterial ◽  
And Function

Riparian forests were frequently cleared and converted to agricultural pastures, but in recent times these pastures are often revegetated in an effort to return riparian forest structure and function. We tested if there is a change in the soil bacterial taxonomy and function in areas of riparian forest cleared for agricultural pasture then revegetated, and if soil bacterial taxonomy and function is related to vegetation and soil physicochemical properties. The study was conducted in six riparian areas in south-eastern Australia, each comprising of three land-use types: remnant riparian forest, cleared forest converted to pasture, and revegetated pastures. We surveyed three strata of vegetation and sampled surface soil and subsoil to characterize physicochemical properties. Taxonomic and functional composition of soil bacterial communities were assessed using 16S rRNA gene sequences and community level physiological profiles, respectively. Few soil physiochemical properties differed with land use despite distinct vegetation in pasture relative to remnant and revegetated areas. Overall bacterial taxonomic and functional composition of remnant forest and revegetated soils were distinct from pasture soil. Land-use differences were not consistent for all bacterial phyla, as Acidobacteria were more abundant in remnant soils; conversely, Actinobacteria were more abundant in pasture soils. Overall, bacterial metabolic activity and soil carbon and nitrogen content decreased with soil depth, while bacterial metabolic diversity and evenness increased with soil depth. Soil bacterial taxonomic composition was related to soil texture and soil fertility, but functional composition was only related to soil texture. Our results suggest that the conversion of riparian forests to pasture is associated with significant changes in the soil bacterial community, and that revegetation contributes to reversing such changes. Nevertheless, the observed changes in bacterial community composition (taxonomic and functional) were not directly related to changes in vegetation but were more closely related to soil attributes.

scholarly journals Mutants libraries reveal negative design shielding proteins from mis-assembly and re-localization in cells

2021 ◽  
Author(s):  
Hector Garcia Seisdedos ◽  
Tal Levin ◽  
Gal Shapira ◽  
Saskia Freud ◽  
Emmanuel Levy
Keyword(s):  
Physicochemical Properties ◽  
Protein Complexes ◽  
Internal Symmetry ◽  
Yeast Cells ◽  
Net Charge ◽  
Protein Surfaces ◽  
Oligomeric Protein ◽  
Cellular Context ◽  
And Function ◽  
The Impact

ABSTRACTUnderstanding the molecular consequences of mutations in proteins is essential to map genotypes to phenotypes and interpret the increasing wealth of genomic data. While mutations are known to disrupt protein structure and function, their potential to create new structures and localization phenotypes has not yet been mapped to a sequence space. To map this relationship, we employed two homo-oligomeric protein complexes where the internal symmetry exacerbates the impact of mutations. We mutagenized three surface residues of each complex and monitored the mutations’ effect on localization and assembly phenotypes in yeast cells. While surface mutations are classically viewed as benign, our analysis of several hundred mutants revealed they often trigger three main phenotypes in these proteins: nuclear localization, the formation of puncta, and fibers. Strikingly, more than 50% of random mutants induced one of these phenotypes in both complexes. Analyzing the mutant’s sequences showed that surface stickiness and net charge are two key physicochemical properties associated with these changes. In one complex, more than 60% of mutants self-assembled into fibers. Such a high frequency is explained by negative design: charged residues shield the complex from misassembly, and the sole removal of the charges induces its assembly. A subsequent analysis of several other complexes targeted with alanine mutations suggested that negative design against mis-assembly and mislocalization is common. These results highlight that minimal perturbations in protein surfaces’ physicochemical properties can frequently drive assembly and localization changes in a cellular context.

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