Enzymes And Co-enzymes Flashcards
What conditions do enzymes work in compared to industrial processes?
Enzymes work in relatively mild conditions, such as low pressure and mild temperatures.
What are nerve agents and give examples?
Nerve agents are chemical weapons, examples include sarin and Novichok.
What enzyme do nerve agents bind to at the neuromuscular junction?
Nerve agents bind to the active site of acetylcholinesterase.
What is the effect of nerve agents on acetylcholine (ACh) at the neuromuscular junction?
ACh is not degraded, leading to increased ACh available to bind to nicotinic acetylcholine receptors.
What happens to the motor end plate due to persistent depolarization caused by nerve agents?
The motor end plate becomes refractory, resulting in no more end plate potentials generated in skeletal muscle.
What are ribozymes?
Ribozymes are self-replicating RNA molecules
Where are ribozymes found and what is their function?
Ribozymes are present in the ribosome and catalyse the formation of peptide bonds during polypeptide synthesis.
What does the EC number signify?
The EC number indicates the class of reaction catalysed, with the first number representing the top level code.
True or False: Snake venom toxins can bind to the active site of acetylcholinesterase.
True.
What are the 7 main classes of enzymes
1- oxidoreductase
2- transferase
3- hydrolase
4- lyase
5- isomerase
6- ligase
7- translocases
Define cofactors
Inorganic ions, eg. Fe2+, Mg2+
Define coenzymes
Organic molecules, eg. NAD, NADP, FAD
Outline coenzymes
-many coenzymes derived from vitamin precursors & essential in the diet
What is a prosthetic group?
A coenzyme that tightly binds
-covalently bound cofactor
Define cosubstrates
-type of coenzymes
-loosely bound -> bind and unbind during catalysis
Define holoenzyme
Catalytically active enzyme with its cofactor/coenzyme
Define apoenzyme
Protein moiety of enzyme without cofactor/coenzyme- inactive
What is Gibbs free energy
A measure of the useable or useful energy of a system
What are the components of a holoenzyme
The apoenzyme (inactive) + its coenzyme/ cofactor
What are nucleophiles and electrophiles
Nucleophiles- donate electron pairs to form a chemical bond
Electrophiles- accept electron pairs
What are the four enzyme catalytic strategies
-covalent catalysis
-general acid-base catalysis
-catalysis by approximation
-metal ion catalysis
Outline covalent catalysis
Active site contains reactive group, which becomes covalently bonded to substrate during reaction
Outline general acid-base catalysis
Transfer of protons (donate or accept) to or from intermediate
Outline catalysis by approximation
Binding surface of enzyme brings two substrates into close proximity
Outline metal ion catalysis
-metal ions can act as an electrophile and stabilise negative charge on intermediate
-or facilitate nucleophile formation by co-ordination
-or can act as bride between enzyme and substrate
