Isoenzymes of peroxidase

Another technique that will be of increasing help in our understanding of extractives biosynthesis are detailed studies of the location of various enzymes within the tree. A recent example of such work is that of Stich and Ebermann (55) who showed that isoenzymes of peroxidase and polyphenol oxidase were identical in the sapwood and heartwood of oak. This work shows that there is a potential for polymerization of monomers to lignin in unlignified parenchyma cells at the sapwood/heartwood boundary as well as in the zone of active lignification close to the cambium. It could also help to explain the formation of the heartwood lignin-like polymers mentioned in Section 11.6.5. 

And now a word about the function of the isoenzymes. It has been established that the individual isoenzymes adapt to the physiological circumstances in the different tissues. For example, after infection new isoenzymes of peroxidase can be formed, which appear to assume a protective function. Perhaps, though, another aspect is more important ... 

Galston was able to demonstrate a lowering of enzymatic activity in tissue cultures of the tobacco plant. In medullary tissue of the tobacco plant two isoenzymes of peroxidases are detectable. If such tissue is now grown in culture two additional isoenzymes of peroxidase are found. After addition of lAA these new activities can no longer be detected. 

Escribano, J. et al., SubceUular localization and isoenzyme pattern of peroxidase and polyphenol oxidase in beetroot Beta vulgaris L), J. Agric. Food Chem., 50, 6123,2002. 

APX, ascorbate peroxidase PJiP, Arthromyces ramosus peroxidase BPl, barley grain peroxidase CCP, C3dochrome c peroxidase CIP, Coprinus cinereus peroxidase EXAFS, extended X-ray absorption fine structure HRP, horseradish peroxidase HRP Z (where Z = A1-A3, B1-B3, Cl, C2, D, E1-E6, or N), a specific isoenzyme of horseradish peroxidase HS, high-spin lAA, indole-3-acetic acid LIP, hgnin peroxidase LS, low-spin PNP, the major cationic isoenzyme of peanut peroxidase WT, wild-type 5-c, five-coordinate 6-c, six-coordinate. 

Expression of peroxidases that catalyze crosslinking reactions can he induced by wounding or infection. Well-documented examples include the production of acidic peroxidase isoenzymes in woimded tissue of tobacco (132), potato (133), and tomato (134), and also in wheat plants infected with the powdery mildew fungus, Erysiphe graminis (135). It is known that peroxidase activity can be induced on wounding of horseradish leaves (56), but other mechanisms of defense in horseradish remain to be demonstrated. 

Different tissues contain different isoenzymes of alkaline phosphatase, and the intestinal isoenzyme is not inhibited by levamisole The enzyme used in immu-nohistochemistry is extracted from calf intestine, so that levamisole can be used as an inhibitor without affecting the desired reaction. For labile antigens in the intestine, it is better to switch to the peroxidase method. 

Although HRP is commercially available, it is not currently available in bulk quantities or at a cost that that is sufficiently low to make full-scale applications of enzymatic treatment feasible. It has been suggested that the use of a less expensive and more ubiquitous source of peroxidase could circumvent the problem of enzyme cost. For example, in 1991, the seed coat of the soybean was identified as a rich source of a single peroxidase isoenzyme [84]. Because the seed coat of the soybean is a waste product of the soybean industry, soybean shells could provide an inexpensive and abundant source of peroxidase. Thus, soybean peroxidase (SBP) has the potential of being a cost-effective alternative to HRP for wastewater treatment. 

Aibara S, Yamashita H, Mori E et al (1982) Isolation and characterization of five neutral isoenzymes of horseradish peroxidase. J Biochem 92 531-539... 

Aibara S, Kobayashi T, Morita Y (1981) Isolation and properties of basic isoenzymes of horseradish peroxidase. J Biochem 90 489-496... 

By reaction with glutathione, catalyzed by a membrane-specific isoenzyme of glutathione peroxidase, which is a selenoenzyme. Thus, in... 

Yamaguchi, K., Hori, H., and Nishimura, M., 1995, A novel isoenzyme of ascorbate peroxidase localized on glyoxysomal and leaf peroxisomal membranes in pumpkin. Plant Cell Physiol. 36 1157nll62. 

S Lobos, J Larram, L Salas, D Cullen, R Vicuna. Isoenzymes of manganese-dependent peroxidase and laccase produced by the lignin-degrading basidiomycete Ceriporiopsis subvermispora. Microbiology-UK 140 2691-2698, 1994. 

The plant peroxidase superfamily consists of evolutionarily related heme peroxidases from bacteria, fungi, and plants (28). The superfamily can be divided into three classes based on amino acid sequence (28). CCP and plant cytosolic ascorbate peroxidase fall into class I, and the main role of peroxidases in this class appears to be the removal of H2O2. Class II comprises the extracellular peroxidases such as lignindegrading LIP and MnP CIP and ARP also belong to class II, but their function is unknown. Class III peroxidases include the classical plant secretory peroxidases such as HRP and its isoenzymes, and barley peroxidase. 

Gomez, J.M., A. Jimenez, E. Olmos, and F. Sevilla. 2004. Location and effects of long-term NaCl stress on superoxide dismutase and ascorbate peroxidase isoenzymes of pea Pisum sativum cv. Puget) chloroplasts. J. Exp. Bot. 55 119-130. 

Mader M, Ungemach J, Schloss P 1980 The role of peroxidase isoenzyme groups of Nicotiana tabacum in hydrogen peroxide formation. Planta 174 467-470... 

Isoenzymes of enzymes involved in the first step of a branched biosynthetic pathway may differ in their sensitivity to inhibitors. Thus the enzyme aspartate kinase catalyses in Escherichia coli the first step in the synthesis of lysine, methionine and threonine. Three isoenzymes occur, the synthesis and activity of one is suppressed by L-lysine, the activity of the second is depressed by L-threonine and the activity of the third by homoserine (an intermediate in methionine biosynthesis). Thus accumulation of L-lysine or L-threonine suppresses their own further S3mthesis but does not prevent the activity of the aspartokinase isoenzyme involved in methionine synthesis. Again peroxidase isoenzymes differ in their activity in destroying indol-3yl-acetic acid (lAA) and the pattern of peroxidase isoenzymes can be altered by feeding lAA or gibberellic acid (GA) to plant tissues. 

Maksimov I. V. Gherepanova E. A. Surina O. B. (2010) Effect of chitooligosaccharides on peroxidase isoenzyme composition in wheat calli co cultured with bunt causal agent / / Rus. J. of Plant Physiol. V. 57. P. 131-138. 

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