Govt. Exams
Entrance Exams
Non-competitive inhibition decreases Vmax while keeping Km constant. This occurs when an inhibitor binds to a site other than the active site (allosteric site), preventing product formation regardless of substrate concentration. The Km value remains unchanged because substrate binding affinity is unaffected.
Disulfide bonds are formed in oxidizing environments. The rough endoplasmic reticulum (RER) and Golgi apparatus maintain oxidizing conditions suitable for disulfide bond formation, unlike the reducing environment of the cytoplasm. The enzyme protein disulfide isomerase (PDI) facilitates this process in the ER lumen.
Enteropeptidase (enterokinase), secreted by the duodenal mucosa, cleaves a specific peptide bond in trypsinogen to produce active trypsin, initiating the cascade of pancreatic protease activation.
Above optimal temperature, increased thermal energy disrupts hydrogen bonds and hydrophobic interactions maintaining the 3D structure, causing denaturation and loss of catalytic activity.
Cytochrome c oxidase (Complex IV) contains heme a, heme a3, and copper centers (CuA and CuB) essential for electron transfer and oxygen reduction to water.
CK is abundant in skeletal and cardiac muscle. Elevated CK indicates muscle damage from myocardial infarction, rhabdomyolysis, or muscular dystrophy.
AST catalyzes the transfer of an amino group from aspartate to α-ketoglutarate, making it a transferase. Amylase is a hydrolase, catalase is a lyase, and hexokinase is a ligase.
The Ramachandran plot shows allowed and disallowed combinations of φ and ψ angles for the polypeptide backbone, used to verify the stereochemical quality of 3D protein structures.
Kwashiorkor results from severe protein malnutrition involving deficiency of all essential amino acids, leading to loss of muscle mass and edema despite adequate calorie intake.
In competitive inhibition, the inhibitor competes with substrate for the active site. This increases the apparent Km (requires more substrate to reach half-maximal velocity) while Vmax remains unchanged.
