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Alcoholysis and reverse hydrolysis reactions in organic one‐phase system with a hyperthermophilic β‐glycosidase
Author(s) -
GarcíaGaribay Mariano,
LópezMunguía Agustín,
Barzana Eduardo
Publication year - 2000
Publication title -
biotechnology and bioengineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.136
H-Index - 189
eISSN - 1097-0290
pISSN - 0006-3592
DOI - 10.1002/1097-0290(20000920)69:6<627::aid-bit6>3.0.co;2-7
Subject(s) - chemistry , hydrolysis , lactose , substrate (aquarium) , glycoside , glycoside hydrolase , organic chemistry , chromatography , yield (engineering) , glucoside , solubility , medicine , oceanography , materials science , alternative medicine , pathology , metallurgy , geology
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‐β‐galactoside and/or heptyl‐β‐glucoside, respectively. When alcoholysis of lactose was performed at 37°C with β‐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 β‐glycosidase was used at 90°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 β‐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‐β‐galactoside was formed by alcoholysis, while the released glucose moiety was used in a secondary reverse hydrolysis reaction to produce heptyl‐β‐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. © 2000 John Wiley & Sons, Inc. Biotechnol Bioeng 69: 627–632, 2000.