Final answer:
Alkaline phosphatase and chromogenic substrates are used in the chromogenic detection of target sequences of nucleic acids after blotting procedures.
Step-by-step explanation:
In the chromogenic detection of target sequences of nucleic acids after blotting procedures, the enzyme/substrate combination used is alkaline phosphatase and chromogenic substrates. Alkaline phosphatase is an enzyme that catalyzes the hydrolysis of phosphate groups from molecules, and it can be conjugated to secondary antibodies in the western blotting technique. The chromogenic substrates, when cleaved by alkaline phosphatase, produce colored products that can be visually detected to identify the presence of the target sequences.