Enzymes Flashcards
Describe enzymes as catalysts
increase the reaction rate by decreasing the energy barrier
does not effect delta G or Keq
Characteristics of enzymes that differ from other proteins
- higher reaction rate
- Milder reaction conditions (standard atm pressure, neutral pH, temps less than 100 C)
- High reaction specificity
- Can be regulated (inhibitors, etc)
measurement of enzyme activity
measured in units:
amount of substrate converetd to product in a given amount of time (1 umol/min)
Specific activity
number of units per mg protein
optimum pH of human enzymes
37 C
Discuss pH optimum of enzymes
- optimum pH dependent on where the enzyme is located
- pepsin in stomach ~ pH 2
- Trypsin in intestine ~ pH 8
Oxidoreductase
transfer protons (H) and electrons to go from C-C to C+C
catalyze oxidation-reduction reactions
Examples of oxidoreductase enzymes
Deydrogenase, Oxidase, reductase, peroxidase, catalase, oxygenase, hydrolases
Transferase
Transfer C-, N-, P- containing groups (glcosyl, methyl, phosphoryl)
usually transfer to a cofactor
Examples of transferases
kinase, phosphomutase, transaldolase, transketolase
Hydrolase
- cleaves bonds by adding water
- cleavage of C-C, C-O, C-N and other bonds
Examples of hydrolases
esterases, glycosidases, peptidases, phosphatases
Lyases
cleaves C-C, C-S, C-O, and C-N
results in a C=C (double bond)
Examples of Lyases
Decarboxylases, aldolases, hydratases, dehydratases, synthases
Isomerases
Catalyze geometric rearrangement
** rearrange but dont change the molecular weight
Examples of Isomerases
Racemases, epimerases, isomerases, mutases