Binds 2 Zn(2+) ions per 7S complex. The Zn(2+) ions are bound at the alpha-gamma interfaces. 7S nerve growth factor is composed of two alpha chains, a beta dimer composed of identical chains, and two gamma chains. The presence of Gln-24 prevents cleavage of the activation peptide, which remains attached at the amino end of the mature alpha chain. Belongs to the peptidase S1 family. Kallikrein subfamily. Has no demonstrable enzymatic activity. This may be due to several critical changes in its sequence, relative to those of related proteases.