Govt Exams
In competitive inhibition, the inhibitor competes with substrate for the active site, so more substrate is needed to achieve half-maximal velocity (increased apparent Km), but Vmax remains unchanged.
Km is the substrate concentration at which the reaction velocity is half of Vmax (V = Vmax/2), and it represents the affinity of enzyme for substrate. Lower Km indicates higher affinity.
The Lineweaver-Burk plot is a double reciprocal plot where 1/v is plotted against 1/[S], allowing easy determination of Km (x-intercept) and Vmax (y-intercept) from linear regression.
Chaperone proteins like HSP70 and HSP90 facilitate proper protein folding, prevent aggregation, and assist in maintaining protein stability, though some also work with degradation pathways.
Cooperative binding (positive cooperativity) occurs when binding of one substrate molecule enhances the affinity of the enzyme for additional substrate molecules, as seen in hemoglobin and phosphofructokinase.
Cytochrome c oxidase contains heme a, heme a3, and copper centers (CuA and CuB) essential for electron transfer and oxygen reduction.
The isoelectric point is the pH at which the net charge on the protein is zero, resulting in minimum solubility and maximum precipitation.
Proteases are endopeptidases and exopeptidases that hydrolyze peptide bonds in proteins. Amylase acts on carbohydrates, lipase on fats, and nuclease on nucleic acids.
Hemoglobin has quaternary structure consisting of 2 α-globin and 2 β-globin subunits held together by non-covalent interactions.
Leucine has a nonpolar, hydrophobic isopropyl side chain. Serine and asparagine are polar, while lysine is positively charged.