Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.2.1.23 (beta-galactosidase)
 14,648 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Alcoholysis and reverse hydrolysis reactions were performed enzymatically in one-phase water-saturated 1-heptanol systems. Lactose or glucose was used as substrate to produce heptyl-beta-galactoside and/or heptyl-beta-glucoside, respectively. When alcoholysis of lactose was performed at 37 degrees C with beta-galactosidase from Escherichia coli, the initial rate was 14 nmol/mL min, and the limiting factors were the poor solubility of the substrate in 1-heptanol and low thermal stability of the enzyme. When a hyperthermophilic beta-glycosidase was used at 90 degrees C, the rate was 3.14-fold higher; in this case a higher concentration of soluble lactose in the water-saturated heptanol was available to the enzyme due to the higher temperature. The hyperthermophilic beta-glycosidase was also able to use glucose and galactose as substrates to achieve the reverse hydrolysis reaction. As a consequence, when lactose was used as substrate, heptyl-beta-galactoside was formed by alcoholysis, while the released glucose moiety was used in a secondary reverse hydrolysis reaction to produce heptyl-beta-glucoside. Both reactions followed Michaelis-Menten kinetics behavior. Neither lactose nor heptyl glycosides were hydrolyzed by this enzyme in water-saturated heptanol. However, the conversion was limited by a strong product inhibition and the formation of oligosaccharides, especially at high substrate concentrations, reducing the final glycoside yield.
 ...
PMID:Alcoholysis and reverse hydrolysis reactions in organic one-phase system with a hyperthermophilic beta-glycosidase. 1091 37

Alcoholysis reactions were performed in organic one-phase liquid systems with E. coli beta-galactosidase to produce heptyl-beta-galactoside from lactose and 1-heptanol. The reaction rate was highly dependent on the amount of water solubilized in the alcohol. A larger amount of water led to a system of two liquid phases in which the alcoholysis rate was 73% faster than in the one-phase system. No hydrolysis reaction of either lactose or product was observed in one-phase liquid systems up to 20 h, independent of the water content. Solubility of lactose in the organic phase increased with the water content in the system and the reaction followed the Michaelis-Menten model. Water activity was calculated for heptanol containing different amounts of water and the obtained values were used to estimate the hydration of beta-galactosidase from known models. Enzyme activity correlated with sorbed water, similar to the behavior reported for lysozyme in low water environments. It is concluded that water contribution to enzyme hydration dominates the rate of reaction compared to its effect on lactose solubilization.
 ...
PMID:Effect of beta-galactosidase hydration on alcoholysis reaction in organic one-phase liquid systems. 1106 33