Biochem Exam 3 Stuff

Enzymes

The workers of the cell

Enzymes are proteins that carry out a chemical reaction (Note that RNAs can also do that!)

Enzymes act as catalysts of chemical reactions so the reactions occur at a much faster rate than uncatalyzed reactions

As we will see, they do so through two mechanisms:

• By providing a protected environment

• By providing all of the reactive partners [acids (Asp, Glu, C-term), bases (Lys, Arg, His, N-term), and hydrogen-bonding] in the correct configuration

General Properties of Enzymes:

• Higher reaction rates

10⁶ - 10¹² times greater than those of uncatalyzed reactions and at least ~10⁷ times greater than chemically catalyzed reactions

General Properties of Enzymes:

• Milder reaction conditions

• Near neutral pH, < 100°C, atmospheric pressure

• Chemical catalysis often requires high T, pressure, and pH

General Properties of Enzymes:

• Greater reaction specificity

Enzymatic reactions are generally highly specific for substrates and therefore rarely produce any side products

General Properties of Enzymes:

• Capacity for regulation

Enzymatic catalysis can be regulated

• Allosteric control, covalent modification, and variations in synthesis of the protein (i.e. protein expression)

Geometric and electrostatic complementarity (h=hydrophobic) between enzyme and substrate is…

The basis of a “lock and key” model of enzyme function

Many substrate binding pockets are pre-formed,…

Some adjust to accommodate substrate – this is called “induced fit”