Please enable JavaScript.
Coggle requires JavaScript to display documents.
Properties of enzyme and mechanism of actions (properties of enzymes…
Properties of enzyme and mechanism of actions
properties of enzymes
reusable (unaffected by reactions)
may catalyze reversible or irreversible reactions
fast activity (catalyze thousands or more reactions in one second)
activity is maximum at optimal pH and temperature,beyond denatured
increase the rate of reaction
specific to substrate
globular proteins
required in small amount to catalyze reaction
six classes of enzymes
isomerases
catalyze the
rearrangement of functional group in a substrate molecule
eg. isomerase/ phosphoglucomutase
transferases
catalyze the
transfer of a functional group from one subtrate to another
eg. transaminase/ phosphorylase
hydrolases
catalyze the
breakdown of chemical bond by adding the water molecule
eg. digestive enzyme: sucrase, protease, lipase
lyases
catalyze the
addition or removal of a functional group
eg. decarboxylase/ carboxylase
oxidreductases
catalyze the
transfer of oxygen and hydrogen atoms between substrates/redox reactions
eg. dehydrogenase/ oxidase/ catalase
some need coenzymes to complete the reaction (eg. FAD, FADH2)
ligases
catalyze the
formation of bonds between two substrate molecules by using ATP energy
eg.synthetase
mechanism of enzyme action
activation energy is the
minimum amount of energy to start a chemical reaction ( collisions and breaking molecular bond)
enzymes have active site, which substrate can fit into it. the specificity of an enzyme is due to the
compatible configuration
between the active site and that of the substrate
lock and key model
active site of the enzyme is not flexible (must be exact compatible), enzyme collide with the substrate and bind together to form enzyme-substrate complex
substrate react with complex to form products, product separate with the enzyme
key=substrate , lock=enzyme
active site remain unchanged
induced fit model
binding induced slight change of the shape of enzyme, allowing the substrate to fit into the active side and become fully complementary
enable the enzyme to carry out their catalytic function and product is formed
active site of enzyme is flexible (not exact compatible to the shape of substrate),enzyme collides with the substrate molecule and bind to the active site to form enzyme-substrate complex
enzyme change back to original conformation when product is formed
eg. lysozyme
factors affect enzymatic reaction
pH
deviation from optimum pH range results in excess H+/OH- , alters the functional groups of amino acid in enzyme, causing breaking of hygen bond and ionic bond
change the conformation of active site, substrate cannot fir in, lower the rate of reaction
enzyme effective in narrow range of pH, max rate at optimum pH, different enzyme have different pH
temperature
increase in temp, movement of molecules faster, increase collisions, rate accelerated, every rise of 10 temp, rate is doubled until optimum temp
optimum temp, rate of reaction max
low temp, reaction occur slowly, movement of molecules slow, decrease the chances of colliding ,enzyme inactive
beyond optimum temp, rate of reaction decrease, enzyme denatured, due to breakdown of weak ionic/hydrogen bonding/ disulphide bridge / Van der waals, substrate no longer fit to the active site
concentration of substrate
increase [], rate of reaction increase, more collisions occur, more substrate bind to active site
high [], active site saturated, substrate concentration does not affect the rate of reaction, max rate achieved
low[] ,rate of reaction directly proportional to the [], some of the active site remain free , max rate is not achieved
cofactors
required for efficiency in enzymatic rxn
present in the active site of enzyme
non protein component of an enzyme
bound tightly or loosely to the active site