Linoleate oxidation induced by lipoxygenase and heme proteins: A direct spectrophotometric assay
TL;DR: The catalytic effects of lipoxygenase and heme proteins on linoleate oxidation were studied, using a Tween-solubilized linoleic acid substrate which remained clear over a broad range of pH and permitted the direct spectrophotometric recording of initial rates of conjugated diene formation in the reaction mixture.
About: This article is published in Analytical Biochemistry.The article was published on 1970-03-01. It has received 127 citations till now. The article focuses on the topics: Hemeprotein & Lipoxygenase.
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TL;DR: Results indicate that excess Fe(II), Cu( II) or Cd(II) ions produce oxidative damage in plant leaves.
699 citations
TL;DR: The volatile components of cured and uncured pork are compared and the field of meat flavor is assessed in terms of what has been accomplished and the direction in which it may proceed.
Abstract: Flavor is an important quality attribute which relates to the organoleptic characteristics of meat. Although perception of flavor is a complex phenomenon, odor is the most important single factor contributing to the overall characteristics of flavor. A large number of compounds have been identified in the volatile fraction of red meats and poultry. An overview of the chemical constituents present in the volatiles of beef, pork, mutton, and chicken is presented according to species and arranged by chemical class--hydrocarbons, alcohols, acids, aldehydes, ketones, sulfides, heterocyclic compounds, etc. The volatile components of cured and uncured pork are compared. The field of meat flavor is assessed in terms of what has been accomplished and the direction in which it may proceed. Techniques for analysis of these volatiles are briefly described.
340 citations
TL;DR: In this paper, the antioxidant effect of seaweed extracts was evaluated by determination of lipoxygenase activity and by α, α-diphenyl-β-picrylhydrazyl (DPPH) decolorization.
Abstract: The inhibition of lipid peroxidation and radical scavenging effects were studied to evaluate the antioxidant activity for extracts of 17 species of seaweed The antioxidant effect was evaluated by determination of lipoxygenase activity and by α, α-diphenyl-β-picrylhydrazyl (DPPH) decolorization Lipoxygenase activity was depressed in the presence of aqueous and ethanol extracts of 4 algal species; Sargassum species had the highest antioxidant activity of all the species examined The ethanol extracts of one Sargassum species showed competitive inhibition with the substrate The same species also showed radical scavenging activity in the DPPH decolorization test Comparison of these results shows no relationship between enzyme inhibition and radical scavenging activity
273 citations
Cites methods from "Linoleate oxidation induced by lipo..."
...The assay for lipoxygenase activity was carried out according to the method of Ben-Aziz et al. (1970)....
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TL;DR: Nitric oxide may act as a modulator of the arachidonic acid cascade and in the generation of oxygen-active species and the radical scavenging ability of the nitroxide radical.
Abstract: The present study demonstrated that nitric oxide, which is an important mammalian metabolite, can inhibit oxidation by lipoxygenase, cyclooxygenase and hemoglobin. The inhibition is manifested as a lag-phase that is reversible. The inhibitory effect of nitric oxide on lipoxygenase and cyclooxygenase seems to derive from i) the capability of ·NO to reduce the ferric enzyme to the ferrous form, which is inactive; ii) competition for the iron site available for exogenous ligands; and iii) the radical scavenging ability of the nitroxide radical. Nitric oxide may act as a modulator of the arachidonic acid cascade and in the generation of oxygen-active species.
248 citations
01 Jan 1997
TL;DR: The chemical components of soybeans are discussed with respect to their occurrences, properties, nutritional value, physiological roles, and assay methodology in this paper, where the soybean is one of the most economical and valuable agricultural commodities because of its unique chemical composition.
Abstract: The soybean is one of the most economical and valuable agricultural commodities because of its unique chemical composition. Among cereal and other legume species, it has the highest protein content (around 40%); other legumes have a protein content between 20% and 30%, whereas cereals have a protein content in the range of 8-15%. The soybean also contains about 20% oil, the second highest content among all food legumes. (The highest oil content is found in peanut, which is about 48% on dry matter basis. The third highest oil content is chickpea, which is about 5%. The remaining food legume species have oil contents in the range of 1-3.6%) (Salunkhe et al. 1983). Other valuable components found in soybeans include phospholipids, vitamins, and minerals. Furthermore, soybeans contain many minor substances, some of which, such as trypsin inhibitors, phytates, and oligosaccharides, are known to be biologically active. Others, such as isoflavones, are just being recognized for their powerful ability to prevent human cancers and other diseases (Messina et al. 1994, Chapter 10 of this book). In this chapter the chemical components of soybeans are discussed with respect to their occurrences, properties, nutritional value, physiological roles, and assay methodology.
222 citations
References
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15 Jan 1968
TL;DR: The Radiation Inactivation Method as a Tool to Study Structure-Function Relationships in Proteins Immunoassay with Electrochemical Detection and Theory and Newer Technology Assays for Superoxide Dismutase are studied.
Abstract: Activator Proteins for Lysosomal Glycolipid Hydrolases Isolation and Analysis of Cell Walls from Plant Material Electro-Optical Reflection Methods for Studying Bioactive Substances at Electrode-Solution Interfaces - An Approach to Biosurface Behaviour Isoelectric Focusing in Immobilized pH Gradients: Theory and Newer Technology Assays for Superoxide Dismutase The Radiation Inactivation Method as a Tool to Study Structure-Function Relationships in Proteins Immunoassay with Electrochemical Detection.
4,558 citations
TL;DR: The question of the effect of pH on the inherent activity of the enzyme could not be solved until a water-soluble substrate could be found, and the spectrophotometric method described here is essentially a modification of the methods of Theorell et al. (8) and Tappel (7).
Abstract: Lipoxidase specifically catalyzes the oxidation of methylene-interrupted unsaturated fatty acids such as linoleic, linolenic, and arachidonic acids and their esters, to their res(pective peroxides (3). Various techniques have been devised for the determination of lipoxidase activity, including a colorimetric method based upon coupled oxidation, a manometric method, and spectrophotometric methods (6). The spectro,photometric method was developed after Holman and Burr (4) and Bergstr6m (1) independently observed an increase in ultraviolet light absorption, at 234 m>, when lipoxidase acted upon essential fatty acids. The increase in UV-peak absorption was then related to the amount of peroxide formation which was found to be proportional to time and to enzyme concentration (7, 8). According to Holman and Bergstrom (3), both the manometric and the coupled oxidation methods give aberrant indices of lipoxidase activity because of variations in the degree of dispersion of fatty substrates. The spectrophotometric method, on the other hand, does not have these disadvantages because it employs more homogeneous substrates. Although satisfactory results are obtained when the method is operated at pH 9.0 or above, where the unsaturated fatty acids are present in a solu;ble form, nevertheless, this nonphysiological pH presents a major disadvantage of the spectrophotometric method. It was therefore concluded by Holman and Bergstr6m (3) that the question of the effect of pH on the inherent activity of the enzyme could not be solved until a water-soluble substrate could be found. The method described here is essentially a modification of the methods of Theorell et al. (8) and Tappel (7). The polyunsaturated fatty acid is solubilized by the addition of a detergent, and with this soluble substrate the activities of purified and crude lipoxidase are demionstrated over a wide range of pH. Also, lipoxidase activities in germinating mung beans, over a period of 80 hours, are presented.
386 citations
TL;DR: An understanding of lipoxidase catalysis is of interest in relation to proposals that some enzyme reactions may proceed by chain reactions (g-12) and speculations on possible chain mechanisms are largely without experimental support.
113 citations
TL;DR: Evidence has been presented that each of the fractions contains a different type of fat-peroxidizing enzyme, and experimental results indicate that lipoxidases may occur as two groups, i.e., those active on triglycerides and thoseactive on fatty acids.
106 citations
55 citations