Sugar chains are biopolymers that play various important roles for organisms, and their structures are complex and diverse. Enzymes acting on sugar chains have undergone a wide variety of molecular evolutions. Nevertheless, the limited availability of sugar chains often prevents the investigation of related enzymes, even among enzymes that act on sugar chains comprising only glucose, an essential monosaccharide in nature. Glucans such as starch and cellulose represent a large amount of biomass, and enzymes acting on these glucans have been investigated extensively. In contrast, there is much less known about enzymes acting on glucans with β-1,2-glucosidic linkages (β-1,2-glucans), especially those enzymes involved in degrading β-1,2-glucans. Research on such degrading enzymes has only been undertaken for approximately a decade. In this review, β-1,2-glucan-associated enzymes will be introduced, especially β-1,2-glucan-degrading enzymes such as a glycoside phosphorylase acting on β-1,2-glucooligosaccharides and the identification of two novel β-1,2-glucanases and related enzymes, along with the distribution and physiological role of β-1,2-glucans in nature. [ABSTRACT FROM AUTHOR]