• digestive enzyme
• serine protease (catalytic triad(SER195, HIS97, ASP102); differ in specitificity pockets 
• specificity in large hydrophobic side chains (F,Y,W)
• intermediate from rapid flow kinetics is acyl enzyme intermediate
• all four modes of catalysis 

• 2 types
• chemical: Acid-Base and Covalent 
• Binding: Proximity effect and Transition state stabilization

primary, secondary, tertiary, and quaternery

primary: AA sequence 

secondary: alpha helix and beta sheets

Tertiary: supersecondary 

• motifs and domains 

Quaternary: tertiary put together 

Domains: discrete, independently folded, compact units 

may contrast of motifs

• classified by structure 
• bound to each other through weak interactions formed by AA side chains on the surface of each domain 
• Fold: combination of secondary structures that form the con