Humboldt State University ® Department of Chemistry

Richard A. Paselk

Chem 431


Fall 2008

Lecture Notes: 15 October

© R. Paselk 2008


Example Enzymes

Last time we looked at Chymotrypsin and saw how the catalytic triad functions. Today we will look at a second enzyme illustrating some other aspects of catalysis.

Lysozyme: Have looked at model of Lysozyme - globular with cleft to accommodate substrate (overhead; model). Functions as an antibiotic, hydrolyzing polysaccharide strand in cell walls of bacteria (text Figure 6-24). For Lysozyme the substrate is a carbohydrate polymer. [overhead].


So now let's look at the enzyme itself:


  The carbohydrates, or sugars, are our third group of biomolecules. They are characterized by having a carbonyl carbon (aldehyde or ketone) and multiple hydroxyl groups. The smallest sugars are thus the three carbon trioses, glyceraldehyde (aldotriose) and dihydroxyacetone (ketotriose), text Figure 7-1.

structures of D and L glyceraldehyde and dihydroxyacetone
Note that sugars occur in both D and L forms (text Figure 7-2b). As we shall see the natural sugars are generally D. Let's look at the two families, aldoses and ketoses. The important aldoses (text Figure 7-3a-1,2) include the five carbon aldopentose, ribose:
structural diagrams of D-ribose (open chain) and alpha-D-ribofuranose (closed ring form)
which commonly occurs in the cyclic furanose form.The six carbon aldohexoses, glucose, mannose, and galactose. (text Figure 7-3a-3)

Pathway Diagrams

C431 Home

Lecture Notes

Last modified 15 October 2008