Nerve growth factor: multiple dissociation products in homogenates of the mouse submandibular gland. Purification and molecular properties of the intact undissociated form of the protein

Abstract

occurs as multiple (at least six) molecular species. Five of these species are unstable, and they dissociate in dilute solution at relatively high protein concentrations. The single stable and

Nerve growth factor: a protease that can activate plasminogen.

“…We now show that the completely purified, stable form of NGF described above (2) is also an arginine esterase as well as a highly specific protease that can promote fibrinolysis by converting plasminogen to plasmin. Moreover, release of soluble peptides from fibrin is strictly plasminogen…”

“…Hydrolysis of the several synthetic protease substrates was followed with a Cary model 15 double beam recording spectrophotometer (A = 247 nm: Tos-Lys-OMe, Tos-Arg-NH2, Tos-Arg-OMe; A = 256 nm: Bz-Tyr-OEt). Polyacrylamide gel § It will be shown elsewhere that the enzymic properties of the stable salivary gland NGF used in the present study (2) are strikingly different from those that have been reported for 7S NGF (7, 8)-dif- described (2), was iodinated-as follows: NGF (5.0 1Ag in a total volume of 10 ,l) was added to 2 mCi of Nal25I dissolved in 300 ,ul of 0.40 M potassium phosphate, pH 7.0. Chloramine-T (1 mg/ml dissolved in H20), 10 ul, was added at 250C, followed 30 sec later by 10 ul of a 36 mM solution of 2-mercaptoethanol in H20.…”

“…polypeptide chains (2). Moreover, the stable 116,000-molecular weight NGF is the predominant form of the protein that is secreted in mouse saliva (1,2).…”

“…Moreover, the stable 116,000-molecular weight NGF is the predominant form of the protein that is secreted in mouse saliva (1,2). The origin of the several unstable forms of NGF is not clear, although it has been suggested that they probably arise from proteolytic degradation of the single stable form, either within the submandibular gland in vivo or during the process of isolation in vItro (2).…”

“…Protein concentrations were-measured by absorbance at 280 nm (2) and by the Lowry procedure (12). Hydrolysis of the several synthetic protease substrates was followed with a Cary model 15 double beam recording spectrophotometer (A = 247 nm: Tos-Lys-OMe, Tos-Arg-NH2, Tos-Arg-OMe; A = 256 nm: Bz-Tyr-OEt).…”