Hanging drop Subject

The experimental data on the subject of the surface tensions of such solutions is scanty. The early work of Valson (G.R. LXXIV. 103, 1872) and of Morgan (cf. J.A.G.S. xxxv. 1753, 1913) cannot be considered as reliable. More accurate appear to be the data of Stocker (vibrating jet) Zeit Phys. Ghem. xciv, 149, 1920), who compared his values with those of Grabowski and Pann (Diss. Kdnigsberg, 1904) (capillary rise) and Sentis (hanging drops) Thhe, Paris, 1897). 

Before crystallization trials, the protein was subjected to gel filtration on Superdex-75 (Pharmacia) in 50 mM sodium/potassium phosphate buffer, pH 7.4, containing 1 mM EDTA, 50 mM 2-mercaptoethanol, 150 mM sodium chloride, 5% glycerol and 5% 2-propanol, as described previously (12). The statine-based inhibitor, LP-149 (Ac-Nal-Val-Sta-Glu-Nal-NH2 e Nal is naphtylalanine and Sta is statine) (Fig. 1), was prepared at Lilly Research Laboratories (K. Hui, unpublished results). Crystallization was carried out at 4 °C using the hanging-drop vapor diffusion method as follows 2.5 //I of the FIV PR(D30N) at 7 mg/ml complexed with LP-149 (1 4 molar ratio) in 50 mM imidazole-HCl pH 7.0 containing ImM EDTA and 1 mM dithiothreitol were mixed with an equal volume of 2 M ammonium sulfate, 0.1 M sodium acetate, pH 4.6 (Hampton Crystal Screen, solution 47). Crystals appeared within a few days and reached the size of 0.2 x 0.2 X 0.4 mm in one week. 

Preparation of Hg film electrode. The Hg film electrode, although possessing superior sensitivity characteristics, is more subject to irreproducible behavior than is the hanging Hg drop electrode. The following plating procedure is satisfactory. 

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