Autolysis (biology)

In biology, autolysis, more commonly known as self-digestion, refers to the destruction of a cell through the action of its own enzymes. It may also refer to the digestion of an enzyme by another molecule of the same enzyme.

The term derives from the Greek αὐτο- ("self") and λύσις ("splitting").

Cell destruction

Autolytic cell destruction is uncommon in living adult organisms and usually occurs in injured cells and dying tissue. Autolysis is initiated by the cells' lysosomes releasing digestive enzymes into the cytoplasm. These enzymes are released due to the cessation of active processes in the cell, not as an active process. In other words, though autolysis resembles the active process of digestion of nutrients by live cells, the dead cells are not actively digesting themselves as is often claimed and as the synonym self-digestion of autolysis seems to imply. Autolysis of individual cell organelles can be lessened if the organelle is stored in warm isotonic buffer after cell fractionation.

Use

In the healing of wounds, autolytic debridement can be a helpful process, where the body breaks down and liquifies dead tissue so that it can be washed or carried away. Modern wound dressings that help keep the wound moist can assist in this process.

In the food industry, autolysis involves killing yeast and encouraging breakdown of its cells by various enzymes. The resulting autolyzed yeast is used as a flavoring or flavor enhancer. For yeast extract, when this process is triggered by the addition of salt, it is known as plasmolysis.[1]

In bread baking, the term (or, more commonly, its French cognate autolyse) is described as a period of rest following initial mixing of flour and water, before other ingredients (such as salt and yeast) are added to the dough.[2] The term was coined by French baking professor Raymond Calvel, who recommended the procedure as a means of reducing kneading time, thereby improving the flavor and color of bread.[3] Long kneading times subject bread dough to atmospheric oxygen, which bleaches the naturally occurring carotenoids in bread flour, robbing the flour of its natural creamy color and flavor.[3] An autolyse also makes the dough easier to shape and improves structure.[3]

In the making of fermented beverages, autolysis can occur when the must or wort is left on the lees for a long time. In beer brewing, autolysis causes undesired off-flavors. Autolysis in winemaking is often undesirable, but in the case of the best Champagnes it is a vital component in creating flavor and mouth feel.[4]

See also

• Programmed cell death
• Sub-lethal damage
• Vegemite

References

1. Kevin Kavanagh (2005). Fungi: biology and applications. Chichester: John Wiley & Sons. pp. 138–140. ISBN 0-470-86701-9. Retrieved 2010-07-25.
2. Gisslen, Wayne (2009). Professional baking (5th ed.). New York: John Wiley. p. 136. ISBN 0-471-78349-8.
3. Calvel, Raymond (2001). The taste of bread : a translation of Le Goût du pain, comment le préserver, comment le retrouver. Gaithersburg: Aspen Publishers. p. 31. ISBN 0834216469.
4. J. Robinson (ed) The Oxford Companion to Wine Third Edition p. 54 Oxford University Press 2006 ISBN 0-19-860990-6