C. Enzymes
➢ Biological catalysts that speed up reactions
- Accomplished by lowering activation energy and helping transition state form
➢ Lowers activation energy by:
- Orienting substrate correctly
- Straining substrate bonds
- Providing favorable microenvironment
- Bonding to substrate
➢ Do NOT change the energy of the starting point or the ending point of the reaction. Only lower activation energy
➢ Enzyme Specificity
- Each enzyme catalyzes only one kind of reactions
- Enzyme are usually named after the molecules they target
■ Replace suffix of substrate with -ase
● Ex. maltose catalyzed by maltase - Substrates are the targeted molecules (reactant)
➢ Enzyme-Substrate Complex
- Enzyme brings about transition state by helping the substrate(s) get into position
- Accomplished through active site
- Once the reaction has occurred, the enzyme is released from the complex and restored to its original state
■ Now the enzyme is free react with other substrates again - Induced fit
■ Enzyme slightly changes shape to accommodate the shape of substrates
■ Sometimes certain factors are necessary for this process
■ Cofactors sometimes aid induced fit and also help catalyze reactions
● Nonprotein helpers of enzymes
● Ex. vitamins