Enzymes Flashcards
Explain the difference between anabolic and catabolic reactions and how they are frequently linked in metabolic pathways
Catabolic: breaks bond (releases energy) in form of atp
Anabolic: makes bond (takes energy)
Couple metabolic reactions create complex pathways
Both are required for maintaining the cells energy balance
What type of reaction is generally spontaneous?
Catabolic
Which type of reaction is generally nonspontaneous (note there are occasional exceptions to this rule)
Anabolic
Diagram a general reaction for a synthesis or decomposition.
Identify the reactants the products and the reaction pathway
A+B(reactants) ___> AB (products)
Synthesis
For a typical synthesis reaction indicate the relative energy difference between the reactants and products
For a typical decomposition reaction indicate the relative energy difference between the reactants and products
Synthesis: products will have lower energy than reactants
Decomposition: Product Will have higher energy level than reactant
Explain the concept of activation energy for a reaction
Energy required to start a reaction
How does the activation energy relate to the rate of the reaction
More activation energy equals a slower reaction
less activation energy equals a faster reaction
Why is a compound like butane lighter fluid generally stable
Needs activation energy
What property of reaction is altered by a catalyst and why does the speed up a reaction?
Something that speeds up a reaction without being consumed in the process
lowers the activation energy
Know some of the General properties of enzymes
including
composition nomenclature specificity
Ends in -ase
Composition: protein
Nomenclature: Generally name for substrate or chemical group in which they act
Specificity: Very specific in their action
Explain the function of an enzyme by describing the
Active site
Substrate binding
Function and composition of cofactors
Function and composition of coenzymes
Enzyme is a protein (amino acid)
Active site: location where reactants bind (key fitting into lock) alterations to active site can destroy enzyme
Substrate binding: fit into active site of enzyme (non covalent bond)
Specific substrate only
Function and composition of cofactors: metal that is critically involved in the catalysis or structure “trace element “ Mn, Zn, Cu, Mg, Fe
Function and composition of coenzyme: organic molecule needed for function NAD, FMN, FAD (often does chemistry that amino acid cannot)
**
Describe generally why enzymes tend to have a maximum catalytic activity and under what conditions the maximum catalytic activity is likely to occur including:
Temperature:
Ph
Substrate concentration
Explain how alterations in these conditions may affect enzymatic structure and how in turn this may affect an organism that uses an enzyme
Optimal conditions for enzyme depend on organism and function of enzyme
Temperature: Can cause enzyme to denature
Ph : Can alter ionization of metallic cofactors or denature
Substrate concentration: Low concentration it was low activity high concentration equals high activity Once saturated with enzymes Max rate of reaction occurs
Alterations in these conditions denature the enzyme
Draw and explain representations of the major forms of enzyme inhibition
Competitive inhibition: inhibitor resemble substrate
(Hydrogen bonds) mimics substrate
Non-competitive inhibition: inhibitor does not resemble substrate Alters active site
- feedback inhibition: end product of metabolic pathway inhibits first step of pathway
- allostery: binding occurs at a site distinct from active site
Irreversible inhibition: inhibitor covalently bonds to enzyme (silencing it ) death of enzyme
Explain the structural similarities or difference between substrate and an enzyme inhibitor in the cases of
Competitive inhibition
Non competitive inhibition
Feedback inhibition
Irreversible inhibition
Competitive inhibition: similar mimics substrate
Non competitive inhibition: changes active site (doesn’t mimic)
Feedback inhibition: final product changes active site temporary(different shape from substrate)
Irreversible inhibition: changes active site completely ( different shape from substrate)
Permanent
Difficult question:
The reaction rate for an enzyme is defined as the amount of product formed per second for a given enzyme concentration.
The units are usually concentration of product formed per second P/sec - mM/sec
In the presence of a competitive inhibitor will the reaction rate be lower?
In the presence of a non competitor inhibitor will an enzymes reaction rate be lower ?
What would be the effect of an irreversible inhibitor (very tricky)?
