Lysozyme is an enzyme found in egg white, tears, and other secretions. It is responsible for breaking down the polysaccharide walls of many kinds of bacteria and thus it provides some protection against infection.

Link to discussion of the
enzymatic action of lysozyme.

The primary structure of egg white lysozyme - shown here - is a single polypeptide chain of 129 amino acids. There are four pairs of cysteines that form disulfide bridges between positions

  • 6 and 127
  • 30 and 115
  • 64 and 80
  • 76 and 94

(counting from the N-terminal lysine).

These cross-bridges force us to realize that this polypeptide is not a straight chain (like cellulose, for example). Rather the chain must fold to allow these cysteines to be close to each other.

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24 December 2001