Proceedings of the Physiological Society, 22‐23 April 1966; Louvain Meeting, Belgium: Communications

Abstract

52P PROCEEDINGS OF THE chloride was slowly added to a solution of neurophysin-M containing one of the two hormones or a mixture of both, protein-hormone complexes were precipitated in the form of needle-shaped crystals. A picture of the complex of neurophysin-M with arginine vasopressin is shown in Fig. 1.In the absence of the octapeptide hormones, neurophysin-M remained in solution. It can thus be said that the presence of hormone was a necessary prerequisite for crystallization. The molecular conformation of the complexes remains to be elucidated.In these experiments the protein concentration was 2-5 mg/ml. in a sodium acetate buffer of pH 3*9; the concentration of peptide hormone(s) was 1 mg/ml. Crystallization was achieved in a sodium chloride concentration of 2-5 % (w/v). Sensory switching mechanisms were studied in normal man by programming mixed series of somatosensory stimuli (electrical pulses on a finger of the hand) and of acoustic clicks. The corresponding cerebral evoked potentials were averaged by C.A.T. and Enhancetron digital computers while the subject performed decision tasks involving either the clicks or the finger shocks. In the latter situation the somatosensory evoked potentials show a marked increase in the voltage of later components with no significant change of the early 'primary' component (Desmedt, Debecker & Manil, 1965). Evidence will now be presented on the kinetics of the switching process. Clicks and finger shocks were made to alternate regularly at various rates, and the two computers were triggered to average 200 responses picked up respectively over the parietal hand pro-52P