lab 5

Lab 5: Enzyme Activity BIOL 1111L

Enzymes Enzyme – a protein that serves as a catalyst (a substance that can increase the rate of a reaction)

Substrate – the reactant that is being changed Product – the new molecule created by the reaction

** Enzymes are specific for a certain reaction

** Because the enzyme does not change, it can be used over and

over again

Enzymes – The Equation

The Equation:

Enzyme + Substrate → Enzyme-Substrate Complex → Enzyme + Products

Enzymes: Properties Each enzyme has an optimal pH and an optimal temperature

Enzymes that work in the human body have an

optimal temperature of 37°C (98.6°F)

Enzymes are Proteins Proteins are made up of subunits called amino acids ◦ Each amino acid is joined by a peptide

bond (strong covalent bond) ◦ “Primary Structure”

◦ The protein folds into a 3D shape using hydrogen bonds (weak bonds)

Peptide Bond (Strong)

Hydrogen Bonds (Weak)

Denaturation Denaturation – when a protein “unfolds” (loses its 3D structure) due to the breaking of hydrogen bonds ◦ Can be caused by heat or extreme pH changes

* Weak bonds holding together the 3D structure

are broken

* Strong bonds holding together the primary

structure are not broken

Denaturation and Enzymes A denatured enzyme cannot bind to the substrate

A denatured enzyme cannot catalyze reactions!!

Today’s Experiment We will be investigating the enzyme catecholase

Catecholase – catalyzes the conversion of catechol to benzoquinone (and the apples will ◦ become brown)

The Equation:

Catecholase + Catechol → Catecholase-Catechol Complex → Catecholase + Benzoquinone

Catecholase Catecholase Catecholase

Catechol

Catechol Bezoquinone

Bezoquinone

Today’s Experiment Test the effect of pH ◦ Soak your apple with substances of different pH values and observe the browning.

Test the effect of temperature ◦ Put your apple slices at different temperatures and observe the browning.