TOPIC 2, 7 & 8 BIOCHEMISTRY2.5 & 8.1 Enzymes

Read & Consider Understandings 2.5.1-2.5.2 & 8.1.1-8.1.2

1 - ENZYMES

• Challenge: by changing one letter at a time, get from ‘TREAD’ to ‘BLINK’. All intermediates must be real English words.

METABOLISM

Consists of linear sequences of enzyme-catalyzed reactions that may be categorized into one of two groups:

Anabolic reactions – Catabolic reactions –

ENZYMES

Enzymes are biological catalysts made of protein.

Enzymes are effective in very small amounts

Remain unchanged at the end of a reaction

ACTIVATION ENERGY

All reactions require an initial input of energy to “get the ball rolling.” In the process of reaction all molecules momentarily exist in an unstable, high energy, intermediate stage. Enzymes decrease the energy needed to get started.

ACTIVE SITE

In a reaction catalyzed by an enzyme the starting substance is called a substrate and will be converted to the product.

Enzymes have specifically formed pockets that match the enzyme to the substrate, active site.

ENZYME SUBSTRATE SPECIFICITY

Enzymes only catalyze one type of reaction or only a very small group of highly similar reactions.

Lock and Key Hypothesis

INDUCED-FIT MODEL

Following the formation of the enzyme-substrate complex, there is a temporary change in shape for the enzyme – induced fit.

LINEAR PATHWAY

Chemical changes within living things occur with a number of intermediate stages. Each stage has its own enzymes. Linear chain pathways: the

product of one reaction will be the substrate of the next until the end product is achieved.

CYCLIC PATHWAYSThe initial substrate enters the cycleEnzyme (1) combines the regenerated

'intermediate 4' with the initial substrate to catalyses the production of intermediate 1.

Enzyme (3) is specific to intermediate 2 and catalyses it conversion to product and intermediate 3

COLLISIONS

Radom movement of enzyme and substrate within aqueous solution brings enzyme and substrate together.

BIOINFORMATICS Used to test 300,000

new chemicals that could act in the fight against malaria.

19 chemicals were identified as useful enzyme inhibitors.

15 chemicals were identified that will “tag” P. falciparum to locate the protozoan.

Read & Consider Understandings 2.5.3-2.5.5

2 – ALTERED ENZYMES

• Do you denature proteins? When?

DENATURATION

Denaturation is a structural change in a protein that results in the loss (usually permanent) of its biological properties. Temperature pH

TEMPERATURE

X is the optimal temperature for enzyme catalysis.

PH

The two enzyme shown in the image illustrate the fact that different enzymes can have very different optimal pHs.

e.g. Blue curve = pepsin (a)= pH3, Red curve =salivary amylase (b)= pH 7.2

SUBSTRATE CONCENTRATION

As the substrate concentration is increased the rate of reaction increases. There are more collisions between the substrate and the enzyme.

ENZYMES IN INDUSTRY

ENZYME VS. CATALYST

The advantaged of using enzymes over chemical catalysts include: They are specific, typically catalyzing one

particular compound or one type of bond only. They are efficient, requiring only a small

quantity of the enzyme to catalyze the production of a huge quantity of product.

They are able to work at normal temperature and pressure, and so require much less energy input.

LACTOSE FREE MILK

•Efficient conversion of lactose to glucose and galactose.•High % lactose conversion is achieved.•All these factors reduce cost particularly on the downstream processing and purification.

Read & Consider Understandings 8.1.3-8.1.4

3 – ENZYME INHIBITION

• Define enzymes, substrate, and active site.

ENZYME INHIBITION

Inhibitors are substances that reduce or completely stop the action of an enzyme. Studies of inhibitors have increased our understanding of: The chemistry of the active sites of enzymes; The natural regulation of metabolism and

which pathways operate; The ways certain commercial pesticides and

some drugs work, namely by inhibiting specific enzymes and preventing particular reactions.

COMPETITIVE INHIBITION:

The substrate and inhibitor are chemically very similar in molecular shape.

The inhibitor will bind to the active site, blocking the substrate.

NON-COMPETITIVE INHIBITION:

The inhibitor can bind to another region of the enzyme molecule.

The bonding of the inhibitor with the enzyme causes structural changes in the enzyme molecule.

END-PRODUCT INHIBITION

Allosteric enzymes have two sites, the active site and an additional site where another molecule could lock in (non-competitive)

End-product inhibition: In this situation the final product acts as the allosteric molecule of inhibitor for the enzyme of the first step (most are allosteric/non-competitive)

WORKS CITED

"Frequently Asked Questions." FAQ. Mosquito.Org, n.d. Web. 01 July 2015.

Haegens, Noel. "Bakery Technology - Enzymes." Class of Foods. N.p., n.d. Web. 29 June 2015.

Lee, Calvin. "Lemon Water and Vitamin C." Continuing Medical Education for Calvin Lee, MD, Modesto Surgeon. N.p., n.d. Web. 29 June 2015.Valaparla, Sneha. "What Are Enzymes?" Read & Digest. N.p., n.d. Web. 29 June 2015.

Walpole, Brenda. Biology for the IB Diploma. 2nd ed. Cambridge, UK: Cambridge UP, 2014. Print.