Nutrient cycling in soils involves biochemical, chemical, and physiochemical reactions, with the biochemical processes being mediated by microorganisms, plant roots, and soil animals. Enzymes are denatured by elevated temperature and extreme pH. The two most remarkable properties of enzymes are their specificity and catalytic efficiency, and it is in these properties that enzymes differ most strikingly from simple catalysts. Temperature affects enzyme activity in various ways; the number of factors controlling the effect of pH on an enzyme‐catalyzed reaction is even greater. The subject of enzyme inhibition requires special consideration, because soils receive a variety of organic and inorganic chemicals. Soil is a living system where all biochemical activities proceed through enzymatic processes. The solutions of the substrates used for assay of phosphomonoesterases and phosphodiesterase are stable for several days if stored in a refrigerator. The activities of several other enzymes have been detected in soils and methods have been developed for their assays. 
A major group of lipolytic enzymes typified by pancreatic lipase consists of nonspecific esterases probably of the serinehistidine type. Another group, the phospholipases 2 of exocrine glands, are calcium activated and have exacting stereo-specific substrate requirements. The enzymes of both groups hydrolyze water-insoluble esters. They must not only adsorb to oil—water or micelle—water interfaces but also must position their active sites toward the matrix (oil droplet, micelle, or membrane) in which the substrate molecules are imbedded, the “supersubstrate” It is postulated that lipolytic enzymes are hydrolases that have developed supersubstrate binding sites for attachment and orientation toward lipids. Such a binding site, which is topographically distinct from the substrate binding sites of the reactive center, may have hydrophobic or electrostatic character. 
Antioxidant enzymes and human diseases
Objectives: To describe the importance of the antioxidant enzymes superoxide dismutase, glutathione peroxidase, and catalase working together in human cells against toxic reactive oxygen species, their relationship with several pathophysiologic processes and their possible therapeutic implications.
Conclusions: Reactive oxygen species (ROS) are involved in the cell growth, differentiation, progression, and death. Low concentrations of ROS may be beneficial or even indispensable in processes such as intracellular signaling and defense against micro-organisms. Nevertheless, higher amounts of ROS play a role in the aging process as well as in a number of human disease states, including cancer, ischemia, and failures in immunity and endocrine functions. As a safeguard against the accumulation of ROS, several non-enzymatic and enzymatic antioxidant activities exist. Therefore, when oxidative stress arises as a consequence of a pathologic event, a defense system promotes the regulation and expression of these enzymes. 
Determination of SOD, POD, PPO and CAT Enzyme Activities in Rumex obtusifolius L.
Aims: The purpose of this study was to measure antioxidant enzyme (polyphenol oxidase, peroxidase, catalase and superoxide dismutase) activities of crude extract of Rumex obtusifolius L. in order to gain insight about this plant’s antioxidant potential.
Study Design: The study was composed of the collection of plant material, extractions of the antioxidant enzymes, activity measurements of the enzymes and finally evaluation of the experimental results.
Place and Duration of Study: Department of Chemistry (biochemistry laboratories), Faculty of Science and Arts of Sakarya University, between June 2015 and July 2015.
Methodology: Enzymatic antioxidant activity of this plant was investigated by carrying out catalase, superoxide dismutase, peroxidase and polyphenol oxidase enzyme activity assays. Enzyme activities of the crude extract were measured by using spectrophotometric method. Optimum pH and temperature values of each enzyme were also determined for measurement of enzyme activities in ideal conditions.
Results: Finally, our results showed that Rumex obtusifolius L. crude extract had good activity for all the enzymatic procedures tested. The activity levels of enzymatic antioxidants polyphenol oxidase, peroxidase, catalase and superoxide dismutase of the plant were found to be 12.8; 195.2; 38.7; 11.6 EU/mL, respectively. Optimum pH and temperature values of all the enzymes (except PPO: optimum temperature 30°C) tested were also found to be 7.0 and 25°C, respectively.
Conclusion: Our results demonstrate that this edible plant, Rumex obtusifolius L., might be a potential source of natural antioxidants with good antioxidant enzyme capacity. 
Influence of Soil Ameliorants, Manures and Fertilizers on Bacterial Populations, Enzyme Activities, N Fixation and P Solubilization in Peanut Rhizosphere under Lateritic Soil
The aim of this study was to investigate relative efficacy of different organic wastes like farmyard manure (FYM) and water hyacinth (WH) and industrial wastes like paper factory sludge (PFS) on balancing with chemical fertilizers (CF) along with soil ameliorants viz., lime (L) or rice husk ash (RHA), another industrial waste, on dry matter production and biological properties of the rhizosphere soil of peanut (Arachis hypogaea), grown as intercrop with sabai grass (Eulaliopsis binata) in acid lateritic soil. Population of symbiotic nitrogen fixing and phosphorus solubilizing bacteria, activity of dehydrogenase and phosphatase enzymes (i.e. acid and alkaline phosphomonoesterases), nitrogen accumulation in nodules and phosphorus solubilizing power of rhizosphere soil were measured after 25, 50, 75 and 100 days after sowing (DAS) of peanut for two years. Results showed significant effects of nutrient sources and growth stages of the crop on the microbial activities. Higher values of all the biological properties and plant growth parameters were recorded significantly under the integrated application of CF and any of the organic or industrial wastes over sole application of CF. Among three organic or industrial wastes WH was superior to others regarding microbial activities at 25 DAS, whereas PFS became superior at 50, 75 and 100 DAS. Application of lime or RHA improved the activity of dehydrogenase and alkaline phosphomonoesterase enzymes, while decreased acid phosphomonoesterase activity. This study revealed that integrated application of organic or industrial wastes, soil ameliorants and inorganic fertilizer, could improve the biological properties of an acid lateritic soil as well as the dry matter production of peanut, intercropped with sabai grass under lateritic soil. 
 Tabatabai, M.A., 1994. Soil enzymes. Methods of Soil Analysis: Part 2 Microbiological and Biochemical Properties, 5, pp.775-833.
 Brockerhoff, H., 1974. Lipolytic enzymes.
 Matés, J.M., Pérez-Gómez, C. and De Castro, I.N., 1999. Antioxidant enzymes and human diseases. Clinical biochemistry, 32(8), pp.595-603.
 Alici, E. and Arabaci, G. (2016) “Determination of SOD, POD, PPO and CAT Enzyme Activities in Rumex obtusifolius L.”, Annual Research & Review in Biology, 11(3), pp. 1-7. doi: 10.9734/ARRB/2016/29809.
 Basu, M., Bhadoria, P. B. S. and Mahapatra, S. C. (2011) “Influence of Soil Ameliorants, Manures and Fertilizers on Bacterial Populations, Enzyme Activities, N Fixation and P Solubilization in Peanut Rhizosphere under Lateritic Soil”, Microbiology Research Journal International, 1(1), pp. 11-25. Available at: https://www.journalmrji.com/index.php/MRJI/article/view/5983 (Accessed: 30November2020).