BIO NMDCAT

Allosteric regulation involves binding to a regulatory site, which induces a conformational change transmitted to the active site, modifying its affinity or efficiency.

Carbonic anhydrase is so efficient that the rate-limiting step is the diffusion of the substrate into the active site.

Malonate is a structural analog of succinate and competes for the active site of succinate dehydrogenase, demonstrating competitive inhibition.

Higher temperatures increase molecular kinetic energy, leading to more frequent and forceful collisions that increase the chance of overcoming the activation energy barrier.

Activation of zymogens requires specific, irreversible proteolytic cleavage to remove a blocking peptide, allowing the protein to fold into its active conformation.

Once all substrate is consumed, adding more enzyme cannot generate more product, and the reaction rate plateaus due to substrate depletion.

The lock-and-key model proposes that the enzyme's active site (lock) is a rigid, pre-shaped template perfectly complementary to a specific substrate (key).

A mutation in the small number of residues forming the active site would directly abolish enzyme function, unlike mutations in distant structural or surface regions.

Group specificity means an enzyme acts on a family of structurally related substrates (like alcohols) due to shared functional groups.

The complete, active enzyme (holoenzyme) consists of the protein part (apoenzyme) and a cofactor. Removing the cofactor leaves the inactive apoenzyme.

Feedback inhibition is a regulatory mechanism where the end product of a pathway inhibits an enzyme acting earlier, preventing overproduction.

Enzymes accelerate reactions by stabilizing the transition state and providing an alternative reaction pathway with a lower activation energy.

At saturating substrate concentrations, the reaction rate is limited by enzyme concentration. Increasing the amount of enzyme creates more active sites and increases Vmax.

Enzyme specificity results from the chemical complementarity between the active site and the substrate's transition state.

Unlike inorganic catalysts, enzymes are highly specific and their activity is finely regulated by cellular mechanisms like allosteric control.

By lowering the activation energy, enzymes allow a much larger proportion of substrate molecules to reach the transition state at a given temperature, increasing the reaction rate.

The protein portion alone is the inactive apoenzyme, which requires a non-protein cofactor to form the complete, active holoenzyme.

Enzyme specificity arises from the unique 3D structure of the active site, which contains amino acid R-groups positioned to form interactions only with a specific substrate.

The induced fit model is exemplified by conformational changes in hexokinase upon glucose binding, which correctly orient ATP for catalysis.