Is Latex a Protein?

text excerpted from http://gasnet.med.yale.edu/gta/latex/latex.html

structures from Organic Chemistry by Fox and Whitesell

illustrations by L. Van Warren

• Latex is the milky sap of the commercial rubber tree, Hevea Brasiliensis. It is a complex intracellular product of a system of cells that synthesise a polymer (cis-1,4-polyisoprene), which is the main component of natural rubber.

The polymer cis-1,4-polyisoprene. The repeating subunit is shown in parenthesis.

2D ChemDraw File, Chem3D File for molecular dynamics

• Latex contains hundreds of proteins, including enzymes that are involved in the biosynthesis of the rubber molecules. Protein fractions in latex are responsible for the Type I (anaphylactic) allergic reactions that make latex allergy an important problem in anesthesia.

• Most natural rubber is produced in Africa and South Asia. Trees are tapped for latex, by cutting a spiral groove in the bark and placing a spout and collection cup, containing ammonia or some other preservative, at the bottom. By centrifugation a concentrated product is obtained. Latex is made heat-stable and elastic by vulcanization (heating in the presence of sulphur). Additional chemicals, such as accelerators, and antioxidants are added for strength, stretch and durability. These additives may be responsible for Type IV (contact dermatitis) allergic reactions.

• Trans-polyisoprene is a harder natural polymer. Gutta-percha is an example. This material is obtained from a different species of rubber tree, and is widely used in dentistry.

• Natural rubber is derived from latex, and should be distinguished from synthetic rubber, derived from petrochemicals. Synthetic rubber does not contain allergy-inciting plant proteins but is virtually identical to natural rubber in its physical properties.