Linamarase, or beta-D-glucosidase (), is an enzyme found in many plants including cassava and the

butter bean Butterbean may refer to: * Lima bean ''Phaseolus lunatus'', an edible legume * Runner bean ''Phaseolus coccineus'', grown both as an edible bean and as an ornamental plant *''Lablab'' known as butter bean in the Caribbean People * Butterbean Lo ...

. In cassava it is found in the

cell wall A cell wall is a structural layer surrounding some types of cells, just outside the cell membrane. It can be tough, flexible, and sometimes rigid. It provides the cell with both structural support and protection, and also acts as a filtering mech ...

s. When the plant is chewed or ground, it exposes the enzyme to compounds like linamarin and

lotaustralin Lotaustralin is a cyanogenic glucoside found in small amounts in Fabaceae austral trefoil (''Lotus australis''), cassava (''Manihot esculenta''), lima bean (''Phaseolus lunatus''), roseroot (''Rhodiola rosea'') and white clover (''Trifolium repe ...

which release

cyanide Cyanide is a naturally occurring, rapidly acting, toxic chemical that can exist in many different forms. In chemistry, a cyanide () is a chemical compound that contains a functional group. This group, known as the cyano group, consists of a ...

compounds that can be lethal to the eater. In humans, chronic toxicity is more likely than death. This action of the enzyme is used by many cultures to process cassava into an edible substance. The enzyme converts the cyanide containing compounds into acetone cyanohydrin, which spontaneously decomposes to

hydrogen cyanide Hydrogen cyanide, sometimes called prussic acid, is a chemical compound with the formula HCN and structure . It is a colorless, extremely poisonous, and flammable liquid that boils slightly above room temperature, at . HCN is produced on an ...

(HCN). The HCN then either dissolves readily in water or is released into the air. Not all cyanide can be removed during processing. Linamarase can be inhibited by low pH via a dilute

acid In computer science, ACID ( atomicity, consistency, isolation, durability) is a set of properties of database transactions intended to guarantee data validity despite errors, power failures, and other mishaps. In the context of databases, a sequ ...

References

T. Itoh-Nashida, M. Hiraiwa and Y. Uda 1987. "Purification and properties of beta-D-glucosidase (linamarase) from the butter bean, Phaseolus lunatus".
Last accessed 13 November 2005.
Heuberger, Christoph. 10 May 2005. "Physicochemical properties of cassava tubers with focus on cyanide content in fermented products".
Last accessed 13 November 2005. EC 3.2.1 Enzymes {{3.2-enzyme-stub