The 2A proteinase of human rhinovirus is a zinc containing enzyme.

The 2A proteinase of human rhinovirus (HRV) 2 is a cysteine proteinase which is not inhibited by metal chelating agents. However, total hydrolysis of highly purified HRV2 2A followed by atom emission spectroscopy demonstrated that HRV2 2A contains 1 mol of zinc per mole of enzyme. Furthermore, Zn depletion of the enzyme led to a loss of proteolytic activity which could subsequently be restored by Zn supplementation.