TYPES OF PROTEIN IN LENS

Human Lens

Lens of a human eye is a transparent, biconvex, crystalline structure 

It is composed of water (65%) and proteins (34%) 

               Protein Content of lenses

Higher than that of any organ of the body

It consists of following types 

-Water Soluble or Crystallins

-Alpha crystallins _31.7%

-Beta crystallins _53.4%

-Gamma crystallins _1.5%

-Water Insoluble or Albuminoids 

Alpha-crystallins  

-Having highest molecular weight (10)6 

-M.W. of A chain – 19,500

-M.W. of B chain – 22,500

-α-Crystallins is a polymer compound and is made by fifty monomers.

 

Beta-crystallins

-M.W. – 5x104 to 2x105

-β-Crystallins have high thiol concentration & disulphide bond linkage

Gamma-crystallins 

-These are the smallest crystallins.

-Composed of monomers only.

-Gamma-crystallin level is high in nucleus of the lens than its cortex.

-Having four fraction which are immunologically identical except fraction II.

Insoluble proteins (Albuminoids)

-Insoluble Albuminoids _12.5%

As the lens age gets older, its protein composition is altered, by an increased concentration of high –molecular weight lens protein. In a mature or hypermature cataract, these proteins are released through microscopic opening in the lens capsule.