Nomura Koji, Sugimoto Kazuhisa, Nishiura Hiromi, Ohdan Kohji, Nishimura Takahisa, Hayashi Hideo, Kuriki Takashi
Biochemical Research Laboratory, Ezaki Glico Co., Ltd., Osaka, Japan.
Biosci Biotechnol Biochem. 2008 Jan;72(1):82-7. doi: 10.1271/bbb.70429. Epub 2008 Jan 7.
Transglucosylation from sucrose to acetic acid by sucrose phosphorylase (EC 2.4.1.7) was studied. 1-O-Acetyl-alpha-D-glucopyranose was isolated as the main product of the enzyme reaction. We also compared the pH-dependence of transglycosylation catalyzed by sucrose phosphorylase toward carboxyl and hydroxyl groups. With hydroquinone as an acceptor molecule, the transfer ratio of glucose residue was higher at neutral pH. This pH-activity profile was similar to that of the phosphorolysis of sucrose by sucrose phosphorylase, but with acetic acid as an acceptor molecule, the transfer ratio of glucose residue was higher at low pH. These findings suggest that the undissociated carboxyl group is essential to the acceptor molecule for the transglycosylation reaction of sucrose phosphorylase. In a sensory test, the sour taste of acetic acid was markedly reduced by glucosylation. The threshold value of the sour taste of acetic acid glucosides was approximately 100 times greater than that of acetic acid.
研究了蔗糖磷酸化酶（EC 2.4.1.7）催化的从蔗糖到乙酸的转葡糖基化反应。分离得到1-O-乙酰-α-D-吡喃葡萄糖作为酶反应的主要产物。我们还比较了蔗糖磷酸化酶催化的转糖基化反应对羧基和羟基的pH依赖性。以对苯二酚作为受体分子时，在中性pH下葡萄糖残基的转移率更高。这种pH-活性曲线与蔗糖磷酸化酶催化的蔗糖磷酸解反应相似，但以乙酸作为受体分子时，在低pH下葡萄糖残基的转移率更高。这些发现表明，未离解的羧基对于蔗糖磷酸化酶的转糖基化反应的受体分子至关重要。在感官测试中，乙酸的酸味通过糖基化显著降低。乙酸糖苷的酸味阈值比乙酸的酸味阈值大约高100倍。
