Sandbox 35

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Please do NOT make changes to this Sandbox. Sandboxes 30-60 are reserved for use by Biochemistry 410 & 412 at Messiah College taught by Dr. Hannah Tims during Fall 2012 and Spring 2013.

Contents 1 Lysozyme - Hen Egg White (HEW) 2 History 3 Structure 3.1 Basics 3.2 Secondary Structures 3.3 Ligands and Intermolecular Forces 4 Catalytic Reaction 4.1 Mechanism 5 Current Uses 6 References

Lysozyme - Hen Egg White (HEW)

Lysozyme is an enzyme that breaks down cell walls by hydrolyzing certain glycosidic linkages in the peptidoglycan of cell walls. It is found in the cells and secretions of various vertebrates, and likely functions as an bacteria-killing or -disposal agent. The lysozyme found in hen egg white has been investigated more thoroughly than other species of lysozyme, and so is better understood then most enzymes.^[1] The PDB code of HEW lysozyme shown on this page is 3IJU and the assigned EC number for lysozyme is EC 3.2.1.17.

History

The enzyme Lysozoyme was first discovered and named in 1922 by Alexander Fleming. Fleming accidentally contaminated petri plates containing gram-positive bacteria with nasal mucous. After this contamination, he found that the bacterial cells on the petri plates had been lysed. He continued to investigate the cause of the cell lysis, and discovered lysozyme.^[2] He also discovered that lysozyme only works on gram-positive cells, and not on gram-negative cells. Gram-negative cells have an outer cell membrane containing lipopolysaccharide, which cannot be digested by lysozyme.^[3]

The structure of HEW Lysozyme was investigated and found out in 1965 by David Phillips, making it the first enzyme to have its structure determined. Phillips initially elucidated the structure through X-Ray crystallography and then continued his investigation of substrate binding by building models of the enzyme.It was through this larger-scale model building that Phillips was able to identify the catalytic site of lysozyme.^[4]

Structure

Basics

spinqualitylabelsall models Basic Structure of HEW Lysozyme. Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image

HEW Lysozyme is a small enzyme, weighing 14.3 kD and containing only 129 amino acid residues. From his determination of the structure, Phillips found that lysozyme had an ellipsoidal shape and a prominent cleft which acted as the sustrate-enzyme binding site. This can be seen best when looking at a surface view of the protein.

Secondary Structures

Ligands and Intermolecular Forces

Catalytic Reaction

Mechanism

Current Uses

References

1. ↑ Voet, D., Voet, J., Pratt, C.(2008) Fundamentals of Biochemistry: Life at the Molecular Level, 3rd edition. John Wiley and Sons, Inc.
2. ↑ copyright 2006-2008. http://lysozyme.co.uk/
3. ↑ http://en.wikipedia.org/wiki/Gram-negative_bacteria
4. ↑ Voet, D., Voet, J., Pratt, C.(2008) Fundamentals of Biochemistry: Life at the Molecular Level, 3rd edition. John Wiley and Sons, Inc.