ENZYMES: Nomenclature, Kinetics, and Mechanisms of Catalysis Flashcards
These are biological catalysts which are predominantly protein in nature
Enzymes
How do enzymes speed up reactions?
Lowering of activation energy
The process of catalysis
Two-step process
The first process of catalysis
Enzyme-substrate complex formation
Second step in the process of catalysis
Conversion of substrate to product
How are enzymes classified?
They are classified in the type of reaction they catalyze.
Six classifications of enzyme reactions
Oxidoreductase, Transferase, Hydrolase, Ligase, Lyase, and Isomerase
Units involved in measuring enzyme activity
Km, Vmax, and Kcat
Factors affecting enzyme activity
Enzyme concentration, substrate concentration, temperature, pH, and the presence of inhibitors.
What competes against the substrate in binding to the active site.
Competitive inhibitors
What affects enzyme conformation and binding of substrate to the active site?
The binding of non-competitive inhibitors to allosteric region
Compounds which an enzyme catalyzes
Substrate
Non-protein organic molecule, frequently a B-vitamin, that acts as a co-factor
Coenzyme
Non-protein portion of an enzyme that is necessary for catalytic function.
Cofactor
The protein part of an enzyme
Apoenzyme
The coenzyme or cofactor that is tightly bound to the apoenzyme.
Prosthetic Group
The term called for the binding of am apoenzyme and prosthetic enzyme
Holoenzyme
A specific portion of the enzyme to which a substrate binds during reaction.
Active site
Any process that initiates or increases the activity of an enzyme
Activation
The portion on the enzyme surface where inhibitors or activators bind to regulate catalytic reactions.
Allosteric Site
Compounds that slow down the rate of reaction
Inhibitors
A process that makes an active enzyme less active or inactive.
Inhibition
Composition of ribozymes
Nucleic acid
The binding of enzyme and subtrate
Enzyme-subtrate complex
TRUE OR FALSE. Enzymes are highly selective catalysts
TRUE
Enumerate the specificity of enzymes
Bond specificity, group specificity, substrate specificity, optical specificity, geometrical specifity, co-factor specificity.
The mechanisms of catalysis
Lock and Key and Induced fit
A classification of enzymes that involves the process of oxidation-reduction reactions.
Oxidoreductase
An enzyme classification that involves a group transfer process
Transferase
An enzyme classification that involves the breaking of bonds in the presence of water.
Hydrolase
An enzyme classification that involves the addition or removal of double and triple bonds.
Lyase
An enzyme classification that involves isomerization reactions
Isomerase
An enzyme classification that involves the formation of new bonds
Ligase
The measure of how fast an enzyme-catalyzed reaction happens.
Enzyme activity
Considerations in enzyme activity
How fast substrates are utilized and how fast products are formed
What happens when there is a proportional increase in enzyme concentration and rate of reaction.
More enzymes mean more molecules to convert substrate to products.
The rate of reaction wherein it is directly proportional to substrate concentration.
First order kinetics
At high substrate concentration, there is an increase reaction rate plateau because of saturation
Zero order kinetics
The basis of catalytic parameters
The effect of substrate concentration to enzyme activity
The relationship of Michaelis constant and affinity
Inversely proportional
The number of moles of substrate converted to products per mole of enzyme per unit time.
Turnover Number (Kcat)
The relationship of temperature and reaction rate
Directly proportional
Loss of catalytic activity of enzyme
Denaturation
Loss of catalytic activity of enzyme
Denaturation
The effect of change in pH on reaction rates
The change in pH alters the charge of amino acid residues found in active site.
At which an enzyme exhibits maximum activity (Vmax)
Optimal pH
What happens to enzyme activity when pH is not regulated?
Irreversible denaturation occurs causing loss of catalytic activity
Types of inhibitors
Competitive, Non-competitive, and Uncompetitive
It isva reversible inhibitor that competes against substrate in binding to the active site.
Competitive Inhibitor
An inhibitor that binds to allosteric sites and alters enzyme conformation.
Non-competitive Inhibitors
