enzymes Flashcards
enzymes
-enzymes are biological catalysts which increase the rate of metabolic reactions while remaining chemically unchanged at the end of the reaction
activation energy
-activation energy is the minimum amount of energy that reactants/ substrates have to absorb in order for a metabolic reaction to begin
-enzymes allow an alternative reaction pathway with much lower activation energy required for the metabolic reaction, increasing the rate of the metabolic reaction
lock-and-key hypothesis
-active site of enzyme is perfectly complementary to bind and catalyse to only one substrate to form the enzyme-substrate complex
induced fit hypothesis
-active site of the enzyme slightly changes its conformation to bind and catalyse to a related group of substrates to form the enzyme-substrate complex
what do the enzymes hydrolyse?
-amylase hydrolyses starch to form maltose
-maltase hydrolyses maltose to form glucose
-sucrase hydrolyses sucrose to form glucose and fructose
-lipase hydrolyses fats to form fatty acids and glycerol
limiting factors of enzyme activity
-substrate concentration
-enzyme concentration
-temperature
-pH
at lower substrate concentrations,
-not all of the active sites of the enzymes bind to substrates
-hence, an increase in substrate concentrations resulted in an increase in the rate of enzyme-substrate complex formed
-hence, there is an increase in the rate of products formed
-thus, substrate concentration is limiting the rate of reaction
at higher substrate concentrations,
-all active sites of enzymes are saturated with substrates
-hence, the maximum rate of enzyme-substrate complex formed is reached
-hence, the maximum rate of products formation is reached
-thus, other factors like enzyme concentration is limiting the rate of reaction
at lower enzyme concentrations,
-all active sites of enzymes are saturated with substrates
-hence, an increase in enzyme concentrations resulted in an increase in the rate of enzyme-substrate complex formed
-hence, there is an increase in the rate of products formation
-thus, enzyme concentration is limiting the rate of reaction
at higher enzyme concentrations,
-not all of the active sites of the enzymes bind to substrates
-hence, the maximum rate of enzyme-substrate complex formed is reached
-hence, the maximum rate of products formation is reached
-thus, other factors like substrate concentration is limiting the rate of reaction
at temperatures below optimum,
-substrate and enzyme have lower kinetic energy
-hence, enzymes are inactivated
-hence, the rate of enzyme-substrate complex formation is lower
-hence, the rate of products formation is lower
as the temperature increases towards optimum,
-substrate and enzyme have increasing kinetic energy
-hence, the rate of enzyme-substrate complex formation increases
-hence, the rate of products formation increases
at optimum temperature,
-the rate of enzyme-substrate complex formation is at its maximum
-hence, the rate of products formation is at its maximum
at temperatures above optimum,
-substrate and enzyme have too high kinetic energy
-hence, the specific 3-dimensional conformation of the active site is destroyed to be no longer complementary to the substrate
-hence, enzymes are denatured
-hence, the rate of enzyme-substrate complex formation decreases sharply to zero
-hence, the rate of products formation decreases sharply to zero
at optimum pH,
-the rate of enzyme-substrate complex formation is at its maximum
-hence, the rate of products formation is at its maximum
