Latherin and other biocompatible surfactant proteins.

The research article explores and describes the chemical and functional properties of a protein called latherin, abundant in the sweat and saliva of horses. The protein is noted for its highly surface-active properties and its potential for both facilitating evaporative cooling in horses and disrupting microbial growth.

Overview of Latherin

• The researchers highlight the unique aspect of horses and other equids (a group of mammals including zebras and donkeys) that produce protein-rich sweat for temperature regulation. Of these proteins, latherin is largely produced and stands out due to its ability to significantly reduce water surface tension at even low concentrations. This reduction of surface tension likely functions as a wetting agent, helping to spread more sweat across the animal’s pelt and facilitate cooling through moisture evaporation.

Dual Role of Latherin

• The article highlights a potential dual role for latherin: aiding in thermoregulation and controlling microbial growth on horse skin. Latherin temporarily binds to hydrophobic, or water-repelling, surfaces which could disrupt microbial biofilms. Biofilms are colonies of bacteria and avoiding their build-up can be crucial for health, especially as sweat could provide the nutrients necessary for bacterial growth.
• Additionally, latherin is found in horse saliva in considerable amounts. Here, the protein could assist in mastication (chewing) of the fibrous foods in the horse’s diet by reducing surface tension, making the texture of food easier to break down. Similarly, in the oral cavity, latherin’s potential to disrupt biofilms might reduce the adherence of harmful microbes to teeth and oral surfaces, serving as a natural oral hygiene mechanism.

Structural Characteristics of Latherin

• The researchers used neutron reflection experiments to understand how latherin interacts with air/water interfaces. Their results indicated that, upon adsorbing to such an interface, latherin displays significant conformational change, implying that the protein partially unfolds (changes its shape) during incorporation into the interface layer. This structural flexibility likely contributes to the adaptability and effectiveness of latherin in performing its varied biological roles.