Final answer:
DNA recombinase is the enzyme responsible for cleaving interstrand hairpins in V(D)J coding regions, enabling rearrangement of gene segments to produce diverse antibody genes in B cells.
Step-by-step explanation:
The enzyme responsible for cleaving interstrand hairpins in V(D)J coding regions during immune system development is known as DNA recombinase. DNA recombinase randomly excises and rearranges variable (V), diversity (D), and joining (J) gene segments to create diverse antibody genes in B cells. This process ultimately allows each B cell to produce a unique antibody. The hairpins that are formed during this recombination process are cleaved by the recombinase to allow the DNA strands to properly rejoin, ensuring the continuity of the DNA code.