Lysin

Article By:

Treffers, Henry P. Department of Pathology, School of Medicine, Yale University, New Haven, Connecticut.

Last reviewed:August 2020

DOI:https://doi.org/10.1036/1097-8542.393800

A term used in biology to describe substances that will disrupt a cell, with the release of some of its constituents. Unless the damage is minor, this action leads to the death of the cell. Lysins vary in the range of host species whose cells they will attack and in their requirements for accessory factors for lysis; the immune lysins are strictest in their requirements. Erythrocytes are lysed by a wide variety of chemicals, including water and hypertonic salt solutions, which displace the osmotic pressure from that of isotonicity. They are also susceptible to surface-active substances, such as saponin. Many bacteria, such as the staphylococcus and the streptococcus, elaborate one or more hemolysins that will lyse erythrocytes from certain, although not all, species of animals. These patterns may be used in the taxonomic classification of microorganisms. There are a number of other lytic substances, such as lysozyme, an enzyme in the eye aqueous humor and to some extent the bacteriophages, which attack diverse species of bacteria. These actions are not entirely nonspecific since they depend on the presence of common cell constituents or receptors which need not, however, coincide with those involved in immune lysis. See also: Bacteriophage; Lysogeny; Staphylococcus; Streptococcus

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