Govt Exams
Allosteric enzymes have regulatory sites distinct from active sites and show cooperativity, resulting in sigmoidal kinetics rather than hyperbolic kinetics seen in simple enzymes.
Ca²⁺ is required for enzymatic activity and is not consumed in the reaction, making it a cofactor. Many proteases require metal ions as structural or catalytic cofactors.
Tertiary structure requires secondary structure elements. Secondary structures (α-helix, β-sheet) fold into tertiary structure; one cannot exist without the other.
Apparent Km = Km(1 + [I]/Ki) = 2(1 + 1/0.5) = 2(1 + 2) = 6 mM. Competitive inhibition increases apparent Km without changing Vmax.
Serine proteases (like trypsin, chymotrypsin) form an acyl-enzyme intermediate through a nucleophilic attack by the active site serine residue.
GAA codes for Glutamic acid (Glu), GUA codes for Valine (Val). This is a non-conservative substitution of a charged to hydrophobic residue.
Cooperative binding (positive cooperativity) occurs when binding of one substrate molecule increases affinity for subsequent molecules, a classic example of allosteric regulation as seen in hemoglobin.
Lipase catalyzes the hydrolysis of ester bonds in lipids. Amylase acts on carbohydrates, protease on proteins, and nuclease on nucleic acids.
Extreme pH causes ionization of amino acid side chains and disruption of protein structure, leading to denaturation and loss of enzymatic activity.
Quaternary structure involves interactions between different polypeptide chains, not covalent peptide bonds. Only non-covalent interactions maintain quaternary structure.