Enzyme p-glucuronidase

Marshall, T., Shult, P., and Busse, W.W., Release of lysosomal enzyme p-glucuronidase from isolated human eosinophils, J. Allergy Clin. Immunol, 82, 550, 1988. 

Enzyme P-glucuronidase suspension from E. coli K 12 source (EC 3.2.1.31). At 37°C the solution should have at least 140 U/mL of activity. 

Bossart and Bienz (1979) showed that poliovirus-infected enucleated HEp-2 cells exhibited the same cytopathic effect as poliovirus-infected nucleated cells. However, enucleated cells did not show the same redistribution of lysosomal enzymes (p-glucuronidase and p-glucosaminidase) into the cytoplasm as do infected nucleate cells however, it should be noted that enucleated cells do not support the replication of poliovirus as well as do nucleated cells. A temporal analysis of the events occuring in poliovirus-infected cells, as well as their cellular location, was made by Bienz et al. (1980). By kinetic analysis, viral protein synthesis was found to reach a maximum at 2.5 hr before cell alterations can even be detected. Poliovirus RNA synthesis reached a peak later (at 3.0-3.5 hr postinfection) when new vacuoles can be seen, although viral RNA synthesis continues as vacuoles coalesce to form the typical poliovirus cytopathic effect. Therefore, these authors consider that viral RNA synthesis and not protein synthesis is more closely related to structural changes possibly this could also include lysosomal structural changes. 

Figure 4. Effect of hyperosmolality on lysosomal enzyme release from rabbit neutrophils. Cells were preincubated 10 min at 37 C in either regular HEPES buffer at 320 mosmol/kg ( ) or in HEPES buffer with 0.3-M sucrose at 680 mosmol/kg ( ), 5 Mg/mL cyto-chalasin B was added, cells were stimulated with FMLP, and p-glucuronidase was released into the medium during a 6-min period measured.

Figure 5. Inhibition of lysosomal enzyme release from neutrophils by increased osmotic strength. Cells were preincubated for 10 min at 37°C in regular buffer containing no additions (o), or containing sodium sulfate ( ), sodium HEPES ( ), or sucrose ( ) to increase the osmotic strength. Cells were treated with cyto-chalasin B (5 arid FMLP (10" M) and p-glucuronidase was...

Groves and Teng (1992) investigated the effect of compactional pressure on biologically active proteinaceous enzymes such as a-amylase, P-glucuronidase, lipase, and urease. Assaying the activity of these enzymes before and after the compaction... 

Coumarins also have a C6-C3 skeleton, but they possess an oxygen heterocycle as part of the C3-unit. There are numerous coumarins, many of which play a role in disease and pest resistance, as well as UV-tolerance. The coumarin umbelliferone (1.21) is popular in enzyme assays. Umbelliferone esters can be used as a substrate for non-specific esterase enzyme assays and in fluorescent immunoassays (Jacks and Kircher, 1967). In order to quantify the enzyme activity of the popular reporter gene P-glucuronidase (GUS), plant extracts can be incubated with 4-methylumbelliferyl P-D-glucuronide (4-MUG 1.22), which upon hydrolysis... 

A novel l yR]uzt n in-degradmg enzyme hns been isolated, purified, and characterized from Antarctic krill (Euphausia superba) [28]. Preliminary investigations show that the enzyme acts as an endo-p-glucuronidase. 

Secondary metabolites can accumulate in the same cell and tissue in which they are formed, but intermediates and end-products can also be transported to other locations for further elaboration or accumulation. For example, TAs and nicotine are typically produced near the root apex, but mostly accumulate within leaf cell vacuoles. Even TA biosynthesis itself involves intercellular transport of several pathway intermediates (Fig.7.9A). P-Glucuronidase (GUS) localization in A. belladonna roots transformed with a PMT promoter-GUS fusion showed that PMT expression is restricted to the pericycle.144 Immunolocalization and in situ RNA hybridization also demonstrated the pericycle-specific expression of H6H.145,146 In contrast, TR-I was immunolocalized to the endodermis and outer root cortex, whereas TR-II was found in the pericycle, endodermis, and outer cortex.85 The localization of TR-I to a different cell type than PMT and H6H implies that an intermediate between PMT and TR-I moves from the pericycle to the endodermis (Fig.7.9A). Similarly, an intermediate between TR-I and H6H must move back to the pericycle. The occurrence of PMT in the pericycle provides the enzyme with efficient access to putrescine, ornithine, and arginine unloaded from the phloem. In the same way, scopolamine produced in the pericycle can be readily translocated to the leaves via the adjacent xylem. 

Fig. 4 Formation of uridine diphosphate glucuronic acid (UDP-GA) and its conjugation with clofibric acid. Inversion takes place during conjugation, the a-D-glucuronic acid forming a P-D-glucuronide. At a more alkaline pH, such glu-curonides may undergo intramolecular rearrangement to forms resistant to enzymic hydrolysis by P-glucuronidase.

---