Enzymes

enzymes

reusable proteins that help speed up chemical reactions by lowering activation energy for specificreactions

What is the difference between reversible and irreversible enzyme inhibitors?

Reversible inhibitors bind to enzymes temporarily, and their effects can be undone by removing the inhibitor.

Irreversible inhibitors bind permanently to the enzyme and inactivate it for good

How do metal ions like lead, mercury, and cadmium affect enzyme function?

by binding to the enzyme's active site or replacing essential cofactors

What happens to enzymes when exposed to extremely high temperatures?

causes enzymes to denature, breaking the bonds in their structure, which changes the shape of the active site and renders the enzyme nonfunctional.

How does pH affect enzyme activity?

Enzymes have an optimal pH range where they function best. Outside this range, changes in pH can disrupt the ionic and hydrogen bonds in the enzyme, altering the active site and reducing activity.

How do substrate concentrations affect enzyme activity?

increasing substrate concentration increases enzyme activity until the enzymes become saturated. Beyond this point, adding more substrate will not increase the reaction rate.

lock and key method

model of enzyme action where the enzyme's active site (the "lock") is perfectly shaped to fit a specific substrate (the "key"), ensuring precise binding and catalysis

enzyme substrate complex

Temporary molecule that is formed when an enzyme comes in contact with its substrate.

how can enzymes be denatured?

• increasing temp (usually over 55C destroys them)

• non-optimum pH levels

• adding heavy metals

what happens to an enzyme if the temperature is too high?

• the maximum enzyme activity will drastically decline because extreme temperatures unravels the enzyme’s 3d shape, deforming its active sites

substrate

reactant in an enzymatic rxn

active site

area of enzyme that binds w/ substrate

degredative reaction

substrate broken into smaller pieces (peptide —> amino acids)

synthesis reaction

substrates joined to form larger molecules

metabolic pathway

series of rxns that proceed in an orderly manner

metabolism

set of chemical reactions within an organism necessary to sustain life and homeostasis

• necessary for converting food to energy

cofactor

Non-protein molecule that assists the enzyme in performing its catalyic function

• Can be inorganic (metallic ions)

• Can be organic (also known as coenzymes)

coenzyme

A non-protein molecule that is a specifiic type of organic cofactor

• Assists enzymatic function, often by carrying chemical groups

• ex: slotting into an active site to help substrate fit better

what is the effect of lowering the temperature on enzyme activity?

• molecular collisions will slow, lowering overall rate of rxn + enzyme activity

induced fit model

• enzyme action where the enzyme's active site adjusts its shape to fit the substrate more closely upon binding, enhancing the enzyme's ability to catalyze the reaction

competitive inhibition

• another molecule competes with true substrate for the active site

allosteric inhibitor

molecule that binds to an enzyme that is NOT the active site (allosteric site)→ changes 3d shape of the enzyme, preventing substrate from binding

allosteric site

a site on an enzyme OTHER THAN the active site

feedback inhibition

• regulatory mechanism in which the end product of a metabolic pathway inhibits an enzyme involved earlier in the pathway, preventing overproduction of the product and conserving resources.

• can be competitive/non-competitive

non-competitive inhibition

an inhibitor binds to an enzyme at a site other than its active site, known as the allosteric site. This binding changes the enzyme's shape or function, reducing its ability to catalyze reactions even if the substrate is bound to the active site.

enzyme composition

2 parts:

• apoenzyme (protein part)

• coenzyme (organic) OR cofactor (non-organic) (non-protein part)

examples of coenzymes and cofactors

coenzymes: vitamins

cofactors: metallic ions

list the factors that affect enzyme activity

• competitive inhibitors

• non-competitive inhibitors

• feedback inhibition

• lack of cofactors/coenzymes

• ph

• temperature

• presence of metallic ions

• substrate concentration

• enzyme concentration

What are the advantages of having complex metabolic pathways in body cells for producing substances like amino acids and ATP?

• Excess energy can be stored (e.g., glycogen or fat) for later use.

• enzymes control each step, ensuring precise production based on the cell’s needs

How can a metabolic pathway be self-regulating?

through feedback inhibition, where the end product inhibits an earlier enzyme in the pathway.

example: In isoleucine synthesis, isoleucine inhibits the enzyme threonine deaminase, stopping its own production when levels are sufficient.