Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.2.1.21 (beta-glucosidase)
 3,280 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The enzymatic catalysis of the decomposition of Salicaceae phenolic glucosides was tested using almond beta-glucosidase and rabbit and porcine liver esterases. The beta-glucosidase catalyzed the complete hydrolysis of salicin and salicortin, yielding saligenin and glucose. Salicortin also produced (+)-6-hydroxycyclohexen-2-one (6-HCH). The acylglucosides were not decomposed by the beta-glucosidase. Both esterases catalyzed the decomposition of tremulacin, salicortin, and 2'-O-acetylsalicortin, releasing tremuloidin, salicin, and 2'-O-acetylsalicin as the main products, accompanied by 6-HCH and catechol. Tremuloidin and 2'-O-acetylsalicin were quite stable under the esterase hydrolysis, and salicin was not decomposed at all.
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PMID:The enzymatic decomposition of salicin and its derivatives obtained from Salicaceae species. 143 41

Salicylates are defensive compounds against a great variety of generalist herbivores. Salicortin and its derivatives are labile compounds that degrade immediately when cell compartmentalization is ruptured, producing a 6-hydroxy-2-cyclohexenone (6-HCH) moiety that is a strong antifeeding cue. We studied the in vitro degradation of willow salicylates in the presence and absence of foliar enzymes at acidic, neutral, and alkaline pHs. Higher substituted salicylates were degraded in the absence of foliar enzymes at alkaline pH and in the presence of foliar enzymes at all three pHs. Salicin and its diglucoside, on the other hand, were degraded only in the presence of foliar enzymes at acidic pH, probably by beta-glucosidase activity. The main degradation products of higher substituted salicylates were salicin, 6-HCH, and catechol in both the absence and presence of enzymes, suggesting that the production of 6-HCH and catechol do not necessarily demand enzymatic activity. We propose that the degradation of salicylates begins with the cleavage of a 1-hydroxy-6-oxo-2-cyclohexen-1-carbonyl moiety by foliar esterases and/or alkaline condition. This moiety is decarboxylated in nonenzymatic reaction to an anion of 2-hydroxy-3-cyclohexenone, which is tautomerized to the enol form and further to the keto form, 6-HCH. Hydroxyketone can be also oxidized to catechol, a substrate of polyphenol oxidases.
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PMID:In vitro degradation of willow salicylates. 1285 23

The inhibition pattern was identified for a reaction system composed of Trichoderma reesei cellulase enzyme complex and lime-pretreated corn stover. Also, the glucose inhibition effect was quantified for the aforementioned reaction system over a range of enzyme loadings and substrate concentrations. Lastly, the range of substrate concentrations and enzyme loadings were identified in which the linear form of the simplified HCH-1 Model is valid. The HCH-1 Model is a modified Michaelis-Menton Model with non-competitive inhibition and the fraction of insoluble substrate available to bind with enzyme. With a high enzyme loading, the HCH-1 Model can be integrated and simplified in such a way that sugar conversion is linearly proportional to the logarithm of enzyme loading. A wide range of enzyme loadings (0.25-50 FPU/g dry biomass) and substrate concentrations (10-100g/L) were investigated. All experiments were conducted with an excess cellobiase loading to ensure the experimental results were not influenced by cellobiose inhibition. A non-competitive inhibition pattern was identified for the corn stover-cellulase reaction system, thereby validating the assumptions of the HCH-1 Model. At a substrate concentration of 10 g/L, glucose inhibition parameters of 0.986 and 0.979 were measured for enzyme loadings of 2 FPU/g dry biomass and 50 FPU/g dry biomass, respectively. At 5 FPU/g dry biomass, glucose inhibition parameters of 0.985 and 0.853 were measured for substrate concentrations of 10 and 100g/L, respectively. The linear form of the HCH-1 Model predicted biomass digestibility for lime-pretreated corn stover over an enzyme loading range of 0.25-50 FPU/g dry biomass and substrate concentration range of 10-100g/L.
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PMID:Enzymatic hydrolysis of lime-pretreated corn stover and investigation of the HCH-1 Model: inhibition pattern, degree of inhibition, validity of simplified HCH-1 Model. 1714 Jul 90

Coastal bermudagrass was pretreated by a low-temperature ammonia fiber explosion (AFEX) process, which soaked the grass in liquid ammonia and then explosively released the pressure. Saccharifying enzymes were systematically applied to the AFEX-treated grass corresponding to low, medium, and high loadings of cellulase/hemicellulase (from Trichoderma reesei), cellobiase, glucoamylase, and pectinase. Three-day sugar yields linearly correlated with the logarithm of the cellulase loading. Supplemental enzymes (cellobiase, pectinase) caused upward shifts in the lines. The linearity and upward shifts are consistent with the HCH-1 model of cellulose hydrolysis. The hydrolysis sugars were converted to ethanol using yeast (Saccharomyces cerevisiae). The solid residues were treated with proteases to attempt recovery of valuable proteins. The low-temperature AFEX pretreatment was able o nearly double sugar yields. At the highest cellulase loadings (30 IU/g), the best reducing sugar and ethanol yields were 53% and 44% of the maximum potential, respectively. Protein recovery was, at most, 59%.
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PMID:Saccharification, fermentation, and protein recovery from low-temperature AFEX-treated coastal bermudagrass. 1862 30