Immobilization of enzymes to water insoluble, anionic porous carriers often results in an apparent shift in the pH optima of the enzyme. The…
Immobilization of enzymes to water insoluble, anionic porous carriers often results in an apparent shift in the pH optima of the enzyme. The physico-chemical interaction likely to cause such a behaviour is
Select an option to attempt
Correct Answer: Option B
Explanation
ELISPOT (Enzyme-Linked ImmunoSpot) assay measures immune responses at the single-cell level. Principle: cells are incubated in wells coated with a capture antibody (e.g. anti-cytokine). Each cytokine-secreting cell creates a localised 'spot' of secreted cytokine directly on the membrane beneath it, captured by the coating antibody. After removing cells, spots are detected with a secondary antibody-enzyme conjugate + substrate, producing a visible precipitate. Each spot = one secreting cell. Advantages: detects even rare cytokine-secreting cells (1/100,000); captures cytokines before dilution or degradation; provides both frequency and secretion level data. This single-cell resolution makes ELISPOT far more sensitive than bulk ELISA for detecting antigen-specific T cells or antibody-secreting B cells.