The purification by immuno-affinity chromatography of bacterial methionyl-(human somatotropin)

kallikrein activities (Fig. 2a). a,-Proteinase inhibitor concentrations (0.28, 4.44 and 4.44mg/ml) were chosen that produced inhibition (to 37,42 and 32% of control rates respectively) of thrombin(substrate S-2238), 7s-NGF(substrate s-2302) and kallikrein(substrate s-2302) catalysed amidolysis respectively. Heparin alleviated a,-proteinase inhibition of thrombin, but did not affect inhibition of 7SN G F or kallikrein (Fig. 2b). Similar effects of a,-proteinase inhibitor and of heparin were observed on 5s-NGF-catalysed amidolysis of substrates S-2288, S-2251 and S-2238 and on kallikrein-catalysed amidolysis of substrate S-2266. Heparins modulate proteinases in several ways, many involving interactions with proteinase inhibitors. Variations in structures of pericellular heparans may affect the ability of these molecules to influence cell-proliferation-associated surface proteinase activities (including those associated with peptide growth factors) (Long & Williamson, 1983). 7 s -NGF activity was compared with that of a glandular kallikrein because of sequence similarities between kallikrein and 7s-NGF y-subunit (Fiedler & Fritz, 1981 ; Lazure et al., 1981), and with that of thrombin because of the known influence of glycosaminoglycans on thrombin activity (summarized in Long & Williamson, 1983). Results reported here suggest that heparin (or heparan) modulation of 7s -NGF activity through the action of antithrombin I11 or a,-proteinase inhibitor is unlikely. A nerve growth factor preparation is able to substitute for component CT of the classical complement pathway, presumably through the action of the y-subunit; tkis action is prevented by the plasma antkroteinase Cls-inhibitor (Boyle & Young, 1982). As Cls-inhibitor is produced by cultured cells, and may be modulated by heparin Qummarized in Long & Williamson, 1983) the action of Cls-inhibitor and heparinmodulated Cis-inhibitor on growth-factor proteolytic activity warrants attention.