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The enormous catalytic power of natural enzymes relies on the ability to facilitate the rate-limiting step in the catalytic cycle [1].Although it has been well noted that for many multi-substrate enzymes the product-release is the rate-limiting step,what strategies these enzymes use to overcome the bottleneck event of product release has remained an open question.Here,to understand better this question,we developed an enzyme model that is capable of integrated description of all the tightly-coupled steps of the catalytic cycle within a unified dynamic energy landscape framework [2,3].We then applied this whole catalytic-cycle model to the multi-substrate enzyme catalysis by taking the adenylate kinase as an example.The model well explained the non-exponential turnover kinetics observed in single-molecule enzymology experiments and the conformation-catalysis interplay.Surprisingly,the in silico simulation revealed that the enzyme utilizes 'steric frustration' between the substrate and product molecules to facilitate the rate-limiting product release.In the catalytic cycles,the binding of a new substrate for the next catalytic round tends to eject the neighbouring product from the previous round by populating a substrate-product co-bound state with steric incompatibility.The steric frustration thereby enables an active mechanism of product release driven by the energy of new substrate binding.This counterintuitive and previously unrealized strategy used by the adenylate kinase to overcome the bottleneck event in catalytic cycle may represent a general mechanism for the mode of action of multi-substrate enzyme catalysis.