Week 3- enzymes

substrate specificity vs reaction specificity

Substrate- some enzymes are highly specific for one molecule (substrate)

Reaction- Some enzymes act on many substrates, but perform same reaction

coenzyme

When the co factor needed with enzyme is organic (has carbon)

6 classifications of enzymes

• Oxidoreductases

• Transferases

• Hydroases

• Isomerses

• Lyases

• Ligases

Oxidoreductases

enzymes that catalyse redox reactions (oxidases and reductases, hydroases for two hydrogens present)

Transferases

transfer from one group to another

Hydroases

catalyse hydrolysis

Isomerases

catalyse conversion of one isomer to another

Lyases

catalyses addition or removal of molecule to create or break double bond

• dehydrase (removal H2O)

• Synthase (addition of small molecule to double bond)

Ligases

Bond formation accompanied by energy release from hydrolysis reaction

Example of Oxidoreductases

Example of Transferases

Example of Hydroases

Example of Isomerses

Example of Lyases

Example of Ligases

How are enzymes named?

[The substrate its acting on] [the type of classification]

lock and key model

Shape of active site on substrate matches enzyme exactly

Induced fit model

The shape of the active site is more flexible to fit enzyme

How enzymes work with temp and pH

Optimal temp 37 degrees

pH optimal 7.4

increase with inc temp but cant go outside 37 or will lose function/denature

allosteric enzymes

Have a regulator bound to them (not at the active site tho) to control them

Negative allosteric control

Occurs when the regulator binds and makes the active site less able to bind substrate

Positive allosteric control

Occurs when the regulator binds and makes the active site more able to bind substrate

3 types of enzyme inhibition

1. Irreversible-penicillin

2. Reversible- competitive and non-competitive

3. Proenzyme-pepsin and trypsin

zygmogen

proenzymes- ie. pepsin and trypsin digestive enzymes active when it reaches destination

How do proenzymes activate?

They carry extra amino acids and let go once at their destination causing them to carry out desired function

Competitive vs non-competitive reversible enzymes

Competitive Inhibition

• Inhibitor binds to the active site.

• Competes with the substrate.

• Can be overcome by adding more substrate.

Non-Competitive Inhibition

• Inhibitor binds to an allosteric site (not the active site).

• Changes enzyme shape, reducing activity.

• Cannot be overcome by more substrate.

An enzyme that catalyses the conversion of L-sugars to D-sugars is?

Isomerases

A kinase catalyses which of the following types of chemical reactions?

A. Hydrolysis
B. Oxidation-reduction
C. Phosphorylation
D. Isomerization

phosphorylation

An oxidase catalyzes which of the following types of chemical reactions?

A. Hydrolysis
B. Oxidation
C. Phosphorylation (transfer of a phosphate group)
D. Decarboxylation

Oxidation-reduction

Which type of enzyme catalyzes the breaking of bonds using water?

A. Ligase
B. Isomerase
C. Oxidoreductase
D. Hydrolase

Hydrolase

A decarboxylase enzyme performs which type of reaction?

A. Adds water across a bond
B. Transfers electrons
C. Removes a group without using water or oxidation
D. Rearranges atoms within a molecule

Removes a group without using water or oxidation

An isomerase catalyzes what kind of reaction?

A. Combines two molecules
B. Rearranges atoms within a molecule
C. Transfers phosphate groups
D. Breaks bonds using water

Rearranges atoms within a molecule

Lactate dehydrogenase is what type of enzyme used for what type pf reaction

Oxidoreductase used for an oxidation-reduction

Alanine Transaminase is what type of enzyme

Transferase

Liptase is what type of enzyme

Hydrolase

phosphoglucose isomerase is what type of enzyme

Isomerase

fumerase is what type of enzyme

Lyase

Pyruvate hydroxylase is what type of enzyme?

Ligase

Which enzyme transfers phosphate groups one molecule to another?

Transferase

Which type of enzyme breaks bonds using water?

Hydrase