PMC:3395577 / 11097-13040
Annnotations
{"target":"https://pubannotation.org/docs/sourcedb/PMC/sourceid/3395577","sourcedb":"PMC","sourceid":"3395577","source_url":"http://www.ncbi.nlm.nih.gov/pmc/3395577","text":"Effect of glucose on BGL activity and substrate specificity\nThe enzyme was able to hydrolyze p-nitrophenyl-β-D-glucopyranoside, cellobiose, and p-nitrophenyl-β-D-galactopyranoside, while no activity was detected upon p-nitrophenyl-α-L-arabinofuranoside, p-nitrophenyl-β-D-xylopyranoside, maltose, CMC, and sucrose. p-nitrophenyl-β-D-Galactopyranoside was hydrolyzed at 40% of that of p-nitrophenyl-β-D-glucopyranoside. The dependence of the rate of the enzymatic reaction on the substrates concentration followed Michaelis-Menten kinetics, with Km and Vmax values of 0.62 mM and 64 U/mg for p-nitrophenyl-β-D-glucopyranoside, and for cellobiose 7.9 mM and 120 U/mg under optimal conditions. The effects of the substrate, cellobiose (290 mM), on the enzyme activity were not significant. The Kcat/Km value for cellobiose 13.3 mM-1 s-1 was less than the β-glucosidase from A. oryzae, but the activity of β-glucosidase from A. oryzae was inhibited by cellobiose, and rapidly decreased above 50°C (Table 2). Furthermore, the enzyme activity was enhanced by the concentrations of glucose below 200 mM, and the enzyme activity was increased 110% when adding 100 mM glucose into reaction mixtures (Figure 5). When glucose was increased, the enzyme activity of BGL was gradually inhibited, with a Ki of 600 mM glucose (Figure 5). The properties of the glucose-tolerant β-glucosidase from other microorganisms are summarized in Table 2. As Table 2 shows, these enzymes have many distinct features, especially in their catalytic properties [12,13,18-21].\nTable 2 Characteristics of glucose-tolerant β-glucosidases from T. thermosaccharolyticum DSM 571 and other microorganisms a pNPG: p-nitrophenyl-β-D-glucopyranoside.\nb ND: not determined.\nc It was calculated by the data based on the reference.\nFigure 5 The effects of glucose on BGL activity. Influence of glucose on enzyme activity with p-nitrophenyl-β-D-glucopyranoside as the substrate.\n\nA","divisions":[{"label":"Title","span":{"begin":0,"end":59}},{"label":"Table caption","span":{"begin":1545,"end":1794}},{"label":"Figure caption","span":{"begin":1794,"end":1942}}],"tracks":[{"project":"MicrobeTaxon","denotations":[{"id":"T25","span":{"begin":871,"end":880},"obj":"5062"},{"id":"T26","span":{"begin":921,"end":930},"obj":"5062"}],"namespaces":[{"prefix":"_base","uri":"http://purl.bioontology.org/ontology/NCBITAXON/"}],"attributes":[{"subj":"T25","pred":"source","obj":"MicrobeTaxon"},{"subj":"T26","pred":"source","obj":"MicrobeTaxon"}]},{"project":"2_test","denotations":[{"id":"22571470-20890102-7770694","span":{"begin":1534,"end":1536},"obj":"20890102"},{"id":"22571470-12590497-7770695","span":{"begin":1537,"end":1539},"obj":"12590497"},{"id":"22571470-9758774-7770695","span":{"begin":1537,"end":1539},"obj":"9758774"},{"id":"22571470-15522500-7770695","span":{"begin":1537,"end":1539},"obj":"15522500"},{"id":"22571470-8795205-7770695","span":{"begin":1537,"end":1539},"obj":"8795205"}],"attributes":[{"subj":"22571470-20890102-7770694","pred":"source","obj":"2_test"},{"subj":"22571470-12590497-7770695","pred":"source","obj":"2_test"},{"subj":"22571470-9758774-7770695","pred":"source","obj":"2_test"},{"subj":"22571470-15522500-7770695","pred":"source","obj":"2_test"},{"subj":"22571470-8795205-7770695","pred":"source","obj":"2_test"}]}],"config":{"attribute types":[{"pred":"source","value type":"selection","values":[{"id":"MicrobeTaxon","color":"#95ec93","default":true},{"id":"2_test","color":"#ec93af"}]}]}}