Terms - Biothermodynamics Flashcards
Cofactors
Can be described as non-protein molecules that assist enzymes.
They include two classes: Organic (coenzyme, Ex: Vitamins) and Inorganic (metal ions, ex: Iorn, magnesium)
Ribozyme
RNA that functions as an enzyme
Enzymes
Described as unique molecules, most of which (not all enzymes are proteins) are proteins that catalyze biochemical reactions
- substrate specific
- pH and temp vary
- unique combination of amino acid monomer unit
prosthetic group
- When a cofactor is covalently bound to an enzyme
- Are organic or inorganic non-protein molecules that are found tightly to a protein to facilitate its functions
anabolic
- small molecules are assembled into large ones
- energy is required
catabolic
- large molecules are broken down into small ones
- energy is released
metabolism
Can be described as all the chemical processes that occur within the human body known to sustain life
Cooperativity
as a phenomenon that occurs where an enzyme becomes more receptive to additional substrate molecules after one substrate molecule binds to the active site
- an example: Hemoglobin
Hemoglobin
is a quaternary protein with 4 subunits that each contain an active site for binding of a single oxygen
catalysts
such as an enzyme accelerate the rate of the overall reaction by lowering the activation energy
Km
- known as Michaelis constant and represents the substrate concentration at which the rate of reaction is half of the max velocity of the enzyme or Vmax.
- when Km is elevated, it will result in worse substrate binding
- when Km is lowered, it will result in better substrate binding
Active site
- When a substrate binds to an enzyme at the location known as an active site
- it does so by using the induced fit approach
Activation energy with enzyme or without enzyme
Enzymes have a lower activation energy than when there is no enzyme. (higher activation energy)
Activation energy
can be described as the “hill” a reaction must climb to move forward
- where the role of ATP comes into play (ATP is a common source of activation energy
ATP
is formed via phosphorylation
- ADP and phosphate come together using energy from an energy-rich molecule like glucose
allosteric enzyme
Contain both an active site for the substrate and an allosteric site for the binding of an allosteric effector (activator or inhibitor)
competitive inhibition
occurs when a substance mimics a substrate and inhibits the enzyme by binding at the active site
- increasing substrate concentration will overcome the effect of competitive inhibition
- Vmax: Same
- Km: different
non-competitive inhibitor
molecule binds to the allosteric site of the enzyme, preventing the substrate form binding to the active site and thus, decreasing the maximal rate or Vmax of the reaction
- Vmax: Different
- Km: same
Pepsin
is an enzyme responsible for protein digestion. When active pepsin cleaves proteins via breaking bonds in order to form smaller polypeptides
- inactive form is known as pepsinogen
vmax
represents its maximal velocity of an enzyme
