Enzyme study guide

chemical reactions that occur in living cells (huge range of reactions)

1. Most chemical reactions occur in a sequence of small steps which forms a metabolic pathway

2. Metabolic Pathways contain a chain of reactions

3. Some metabolic pathways form cycles - where the product becomes the reactant in the next pathway

central carbon, amine group, carboxyl, R side group, H on top

breaks down tertiary/quaternary levels

Energy is absorbed, therefore you end with more energy than you started with

forms bonds (+ positive free energy)

“energy in” (ex. dehydration synthesis)

Energy is released, so the released energy is used to fuel an endergonic reaction

breaks bonds (- negative free energy)

“energy out” (ex. hydrolysis)

“usable energy” (the area after the hill on a graph)

energy released after a reaction

enzyme helps release this energy faster

energy needed to fuel a reaction

The top of the hill on a reaction energy graph

(when bonds are broken or formed)

biological catalyst (made of proteins)

isn’t actually part of the chemical reaction, just speeds it up (reduces Ea) (doesn’t change FREE ENERGY)

can be reused, usually end in -ase, reaction specific

reactant that binds to the enzyme (target of the enzyme)

enzyme’s catalytic site

The specificity of an enzyme depends on its 3-D structure

“Lock and Key” = One Enzyme: One Substrate

“Induced Fit” = One Enzyme: Many Substrates

at first the increased substrate will increase the reaction rate, but eventually levels off because of the maximum rate of reaction (enzyme is saturated)

increased reaction rate at first, eventually levels off because not all enzymes can link to a substrate

if you increase the temperature, you can speed up the reaction, but if you decrease the temperature it slows the reactions (too hot = denaturation)

if there is too high or too low pH/salinity the enzyme is denatured, but it can just generally slow down the reaction if its not at its optimum (pH adds or removes H+ while salinity can add/remove cations/anions)

A cofactor is an additional chemical component, they help in reactions that enzymes cannot do alone. (non-protein component!)

A coenzyme is an organic molecule that assists in the catalysis of a reaction (bind temporarily near active site) [*please note that the prosthetic groups would permanently attach]

1. Competitive - Inhibitor/Substrate compete for active site (enzyme and substrate cannot bind)

2. Non-Competitive - Causes enzyme to change shape so that the substrate cant bind

3. Irreversible - Can either permanently bind to the active site or to an allosteric site

Allosteric regulators regulate the activity of an enzyme (with inhibitors, it can keep an enzyme inactive, but it can also make an enzyme active)

End-Product Inhibition is when the end product turns into a non competitive inhibitor, this regulated metabolic pathways by inhibiting a certain amount of product forming during a reaction (ex. becomes too toxic)

An enzyme can be denatured by any extreme change in pH, temperature, or salinity

enzymes physically confined or localized in a certain defined region of space with retention of their catalytic activities, and which can be used repeatedly and continuously