It has been well-established that surface atoms play a vital role in catalysis; however, it is still unclear whether the catalytic performance can be tuned by a core atom away from the surface. The investigation into this issue is complicated, as it is challenging to abstract a core atom from a conventional catalyst. The successful synthesis of atomically precise Au25 and Au24 nanoclusters, where a core atom can be extracted from Au25 to form Au24, provides a new opportunity for unravelling the catalytic properties of a single core-atom. Herein, a distinction has been made between the catalytic activities of Au25 and Au24 in that the Au24 nanocluster exhibits superior activity in the intramolecular hydroamination of alkynes when compared to the Au25 nanocluster.