COMMERCIAL MOUSE AND HUMAN NERVE GROWTH-FACTORS CONTAIN NERVE GROWTH-FACTOR PROHORMONE ISOFORMS

Highly sensitive chemiluminescence immunoblot analysis was utilized to examine the purity of mouse 2.5S-, beta- and 7S nerve growth factors as well as that of recombinant human beta-nerve growth factor obtained from commercial vendors. Three polyclonal antisera and two monoclonal antibodies to 13 kDa nerve growth factor (2.5S NGF and beta-NGF) were employed for assessing the purity of each preparation. In addition, p olyclonal antisera against two prepro-NGF specific domains were used f or immunoblotting analysis to ascertain the identity of high molecular weight nerve growth factor immunoreactive proteins as prohormones. Bo th the mouse and human NGF preparations contained 53 and 60 kDa immuno reactive proteins. Of these, the mouse 60 kDa and the human 53 kDa pro teins strongly immunoreacted with both prepro-nerve growth factor spec ific domain antibodies suggesting that they are two NGF prohormone iso forms. In addition, both the mouse and human nerve growth factor prepa rations contained proteins that were immunoreactive to polyclonal anti sera and monoclonal antibodies to mouse 2.5S and/or beta-NGF. High mol ecular weight aggregates of prohormones were also observed in mouse an d human nerve growth factor samples. In summary, none of the ten NGF s amples examined were pure as stated. Our study cautions investigators in the field to be aware of the presence of nerve growth factor prohor mones and other proteins in various mouse and human nerve growth facto rs sold commercially. (C) 1997 Elsevier Science B.V.