Wood bioadhesives for biocomposites by nonvolatile bioaldehydes generation by specific oxidation of different biomaterials

2021 ◽  
pp. 449-466
Author(s):  
Antonio Pizzi ◽  
Anish Khan ◽  
Abdullah M. Asiri
Keyword(s):  
Specific Oxidation

The Binding and Viscometric Studies of Ni+2, Co+2 and Mn+2 Ions with Protein by Spectrometric and pH Metric Techniques

2019 ◽  
Vol 9 (2) ◽  
pp. 151-162
Author(s):  
Shveta Acharya ◽  
Arun Kumar Sharma
Keyword(s):  
Metal Ions ◽  
Metal Ion ◽  
Protein Molecule ◽  
Vital Role ◽  
Sufficient Evidence ◽  
Structural Requirement ◽  
Nickel Ions ◽  
Cobalt Ions ◽  
Lower Temperature ◽  
Specific Oxidation

Background: The metal ions play a vital role in a large number of widely differing biological processes. Some of these processes are quite specific in their metal ion requirements. In that only certain metal ions, in specific oxidation states, can full fill the necessary catalytic or structural requirement, while other processes are much less specific. Objective: In this paper we report the binding of Mn (II), Ni (II) and Co (II) with albumin are reported employing spectrophotometric and pH metric method. In order to distinguish between ionic and colloidal linking, the binding of metal by using pH metric and viscometric methods and the result are discussed in terms of electrovalent and coordinate bonding. Methods: The binding of Ni+2, Co+2 and Mn+2 ions have been studied with egg protein at different pH values and temperatures by the spectrometric technique. Results: The binding data were found to be pH and temperature dependent. The intrinsic association constants (k) and the number of binding sites (n) were calculated from Scatchard plots and found to be at the maximum at lower pH and at lower temperatures. Therefore, a lower temperature and lower pH offered more sites in the protein molecule for interaction with these metal ions. Statistical effects seem to be more significant at lower Ni+2, Co+2 and Mn+2 ions concentrations, while at higher concentrations electrostatic effects and heterogeneity of sites are more significant. Conclusion: The pH metric as well as viscometric data provided sufficient evidence about the linking of cobalt, nickel and manganese ions with the nitrogen groups of albumin. From the nature and height of curves in the three cases it may be concluded that nickel ions bound strongly while the cobalt ions bound weakly.

scholarly journals Laccases: Versatile Biocatalysts for the Synthesis of Heterocyclic Cores

Molecules ◽  
2021 ◽  
Vol 26 (12) ◽  
pp. 3719
Author(s):  
Ana Catarina Sousa ◽  
Lígia O. Martins ◽  
M. Paula Robalo
Keyword(s):  
Membered Ring ◽  
Low Molecular Weight ◽  
Redox Potentials ◽  
Redox Mediators ◽  
Multicopper Oxidases ◽  
Phenothiazine Derivatives ◽  
Ph Values ◽  
Electron Shuttles ◽  
Specific Oxidation ◽  
Optimal Ph

Laccases are multicopper oxidases that have shown a great potential in various biotechnological and green chemistry processes mainly due to their high relative non-specific oxidation of phenols, arylamines and some inorganic metals, and their high redox potentials that can span from 500 to 800 mV vs. SHE. Other advantages of laccases include the use of readily available oxygen as a second substrate, the formation of water as a side-product and no requirement for cofactors. Importantly, addition of low-molecular-weight redox mediators that act as electron shuttles, promoting the oxidation of complex bulky substrates and/or of higher redox potential than the enzymes themselves, can further expand their substrate scope, in the so-called laccase-mediated systems (LMS). Laccase bioprocesses can be designed for efficiency at both acidic and basic conditions since it is known that fungal and bacterial laccases exhibit distinct optimal pH values for the similar phenolic and aromatic amines. This review covers studies on the synthesis of five- and six-membered ring heterocyclic cores, such as benzimidazoles, benzofurans, benzothiazoles, quinazoline and quinazolinone, phenazine, phenoxazine, phenoxazinone and phenothiazine derivatives. The enzymes used and the reaction protocols are briefly outlined, and the mechanistic pathways described.

scholarly journals Inhibition of cysteine proteinases and dipeptidyl peptidase I by egg-white cystatin

1984 ◽  
Vol 223 (1) ◽  
pp. 245-253 ◽  
Author(s):  
M J H Nicklin ◽  
A J Barrett
Keyword(s):  
Cathepsin B ◽  
Bond Cleavage ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
Dipeptidyl Peptidase ◽  
Egg White ◽  
Reversible Inhibitor ◽  
Cysteine Proteinases ◽  
Peptide Bond Cleavage ◽  
Specific Oxidation

The interactions between egg-white cystatin and the cysteine proteinases papain, human cathepsin B and bovine dipeptidyl peptidase I were studied. Cystatin was shown to be a competitive reversible inhibitor of cathepsin B (Ki 1.7 nM, k-1 about 2.3×10(-3) s-1). The inhibition of dipeptidyl peptidase I was shown to be reversible (Ki(app.) 0.22 nM, k-1 about 2.2×10(-3) s-1). Cystatin bound papain too tightly for Ki to be determined, but an upper limit of 5 pM was estimated. The association was a second-order process, with k+1 1.0×10(7) M-1×s-1. Papain was shown to form equimolar complexes with cystatin. Sodium dodecyl sulphate/polyacrylamide-gel electrophoresis of complexes formed between papain or cathepsin B and an excess of cystatin showed no peptide bond cleavage after incubation for 72 h. The reaction of the active-site thiol group of papain with 5,5′-dithiobis-(2-nitrobenzoic acid) at pH 8 and 2,2′-dithiobispyridine at pH 4 was blocked by complex-formation. Dipeptidyl peptidase I and papain were found to compete for binding to cystatin, contrary to a previous report. The two major isoelectric forms of cystatin were found to have similar specific inhibitory activities for papain, and similar affinities for papain, cathepsin B and dipeptidyl peptidase I. This, together with specific oxidation of the N-terminal serine residue with periodate, showed the N-terminal amino group of cystatin 1 to be unimportant for inhibition. General citraconylation of amino groups resulted in a large decrease in the affinity of cystatin for dipeptidyl peptidase I. It is concluded that the interaction of cystatin with cysteine proteinases has many characteristics similar to those of an inhibitor such as aprotinin with serine proteinases.

New blood culture medium

1977 ◽  
Vol 6 (3) ◽  
pp. 249-256
Author(s):  
C N Shih ◽  
E Balish
Keyword(s):  
Blood Culture ◽  
Growth Medium ◽  
Color Change ◽  
Sodium Succinate ◽  
Blue Color ◽  
Contamination Control ◽  
Oxidation Reduction ◽  
Oxidation Reduction Potential ◽  
Unique System ◽  
Specific Oxidation

A growth medium with a specific oxidation-reduction potential containing peptone, dextrose, sodium succinate, sodium lactate, gelatin, sodium bicarbonate and blue tetrazolium, an indicator dye, in a tris(hydroxymethyl)aminomethane buffer was used to detect the presence of microorganisms in blood. The procedure involved the introduction of blood (and bacteria) into the growth medium with the dye in its colorless state. As the bacteria grew, they converted the dye to a visible blue color (formazan) with their reductases. The growth medium served as its own contamination control, since microbial growth and be detected by a color change before it was used for blood culture. The experiments described herein demonstrate that the composition of this medium (with the dye) provides a unique system that is able to make a reliable and rapid detection of both gram-positive and gram-negative microorganisms and yeasts (Candida albicans) commonly associated with bacteremia.

scholarly journals Cytochemical Demonstration of Oxidative Damage in Alzheimer Disease by Immunochemical Enhancement of the Carbonyl Reaction with 2,4-Dinitrophenylhydrazine

1998 ◽  
Vol 46 (6) ◽  
pp. 731-735 ◽  
Author(s):  
Mark A. Smith ◽  
Lawrence M. Sayre ◽  
Vernon E. Anderson ◽  
Peggy L.R. Harris ◽  
M. Flint Beal ◽  
...  
Keyword(s):  
Alzheimer Disease ◽  
Oxidative Damage ◽  
Peroxidation Of Lipids ◽  
Bulk Analysis ◽  
Age Related ◽  
Cytochemical Demonstration ◽  
Highly Sensitive ◽  
Metal Catalyzed ◽  
Specific Oxidation ◽  
Cytochemical Technique

Formation of carbonyls derived from lipids, proteins, carbohydrates, and nucleic acids is common during oxidative stress. For example, metal-catalyzed, “site-specific” oxidation of several amino acid side-chains produces aldehydes or ketones, and peroxidation of lipids generates reactive aldehydes such as malondialdehyde and hydroxynonenal. Here, using in situ 2,4-dinitrophenylhydrazine labeling linked to an antibody system, we describe a highly sensitive and specific cytochemical technique to specifically localize biomacromolecule-bound carbonyl reactivity. When this technique was applied to tissues from cases of Alzheimer disease, in which oxidative events including lipoperoxidative, glycoxidative, and other oxidative protein modifications have been reported, we detected free carbonyls not only in the disease-related intraneuronal lesions but also in other neurons. In marked contrast, free carbonyls were not found in neurons or glia in age-matched control cases. Importantly, this assay was highly specific for detecting disease-related oxidative damage because the site of oxidative damage can be assessed in the midst of concurrent age-related increases in free carbonyls in vascular basement membrane that would contaminate biochemical samples subjected to bulk analysis. These findings demonstrate that oxidative imbalance and stress are key elements in the pathogenesis of Alzheimer disease.

Chemical Stability of Proteins in Foods: Oxidation and the Maillard Reaction

2021 ◽  
Vol 13 (1) ◽  
Author(s):  
Mahesha M. Poojary ◽  
Marianne N. Lund
Keyword(s):  
Maillard Reaction ◽  
Protein Oxidation ◽  
Oxidation Products ◽  
Protein Carbonyls ◽  
Annual Review ◽  
Publication Date ◽  
Food Protein ◽  
Food Proteins ◽  
Wide Range ◽  
Specific Oxidation

Protein is a major nutrient present in foods along with carbohydrates and lipids. Food proteins undergo a wide range of modifications during food production, processing, and storage. In this review, we discuss two major reactions, oxidation and the Maillard reaction, involved in chemical modifications of food proteins. Protein oxidation in foods is initiated by metal-, enzyme-, or light-induced processes. Food protein oxidation results in the loss of thiol groups and the formation of protein carbonyls and specific oxidation products of cysteine, tyrosine, tryptophan, phenylalanine, and methionine residues, such as disulfides, dityrosine, kynurenine, m-tyrosine, and methionine sulfoxide. The Maillard reaction involves the reaction of nucleophilic amino acid residues with reducing sugars, which yields numerous heterogeneous compounds such as α-dicarbonyls, furans, Strecker aldehydes, advanced glycation end-products, and melanoidins. Both protein oxidation and the Maillard reaction result in the loss of essential amino acids but may positively or negatively impact food structure and flavor. Expected final online publication date for the Annual Review of Food Science and Technology, Volume 13 is March 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

scholarly journals CD1d Selectively Down Regulates the Expression of the Oxidized Phospholipid-Specific E06 IgM Natural Antibody in Ldlr−/− Mice

Antibodies ◽  
2020 ◽  
Vol 9 (3) ◽  
pp. 30
Author(s):  
Tapan K. Biswas ◽  
Paul A. VanderLaan ◽  
Xuchu Que ◽  
Ayelet Gonen ◽  
Paulette Krishack ◽  
...  
Keyword(s):  
Cell Wall ◽  
Streptococcus Pneumoniae ◽  
Oxidized Ldl ◽  
Tissue Homeostasis ◽  
Head Group ◽  
Oxidized Phospholipids ◽  
Global Increase ◽  
Specific Oxidation ◽  
Deficient Mice ◽  
Oxidized Phospholipid

Natural antibodies (NAbs) are important regulators of tissue homeostasis and inflammation and are thought to have diverse protective roles in a variety of pathological states. E06 is a T15 idiotype IgM NAb exclusively produced by B-1 cells, which recognizes the phosphocholine (PC) head group in oxidized phospholipids on the surface of apoptotic cells and in oxidized LDL (OxLDL), and the PC present on the cell wall of Streptococcus pneumoniae. Here we report that titers of the E06 NAb are selectively increased several-fold in Cd1d-deficient mice, whereas total IgM and IgM antibodies recognizing other oxidation specific epitopes such as in malondialdehyde-modified LDL (MDA-LDL) and OxLDL were not increased. The high titers of E06 in Cd1d-deficient mice are not due to a global increase in IgM-secreting B-1 cells, but they are specifically due to an expansion of E06-secreting splenic B-1 cells. Thus, CD1d-mediated regulation appeared to be suppressive in nature and specific for E06 IgM-secreting cells. The CD1d-mediated regulation of the E06 NAb generation is a novel mechanism that regulates the production of this specific oxidation epitope recognizing NAb.

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