“When we consider the immense human significance of sleep, the absolute necessity for us to spend a considerable part of our lives in abject mental annihilation, it is remarkable how little we know about it. …” In these words, Sir John Eccles introduced the recently published Ciba Foundation Symposium on “The Nature of Sleep” (3), in which are described many of the advances which have been made in recent years in our attempts to understand the phenomena which are involved in the state of sleep. In one of the papers included in this Symposium, Bremer (2) reviews the work which has been reported since 1954 on the neurophysiological mechanisms involved in sleep. The relationship of dreaming to the depth of sleep has been investigated by such workers as Kleitman (5), Dement (4) and Wolpert (11). These studies have been made possible by the application of modern techniques of measuring mental activity. The use of electroencephalographic methods has allowed an approximate classification of the different levels of sleep which enables different workers to adopt a standard frame of reference. Measurements of rapid eye movements and of changes in muscle potential during sleep have provided more objective methods of assessing dream activity. Other recent studies have attempted to make an objective assessment of the physical and mental effects of sleep deprivation (Morris et al., 7, Bliss et al., 1, Murray et al., 8, Wilkinson, 9, Williams et al., 10).

SUMMARYPeptides were synthesized based on the cleavage sites in the adenovirus type 2 proteins pVI and pVII. The synthetic peptides were incubated with disrupted, purified adenovirus as a source of proteinase and specific cleavages were monitored by fast protein liquid chromatography and amino acid analysis. Using this approach it was established that all the peptides cleaved were of the form M(L)XGX~G or M(L)XGG~X. Thus we have shown that the adenoviral proteinase recognizes a specific secondary structure formed by a sequence of at least five amino acids, the main determinants of specificity being two and four residues to the N-terminal side of the bond cleaved. We were able to examine the relevant structural features of the peptide substrates by utilizing the CHEM-X molecular modelling package. Using our consensus sequence we were able to predict the cleavage sites in the viral proteins pVIII, pre-terminal protein (pTP), IlK and IIIa. Octapeptides containing the predicted sites in pVIII and the pTP were synthesized and shown to be cleaved by the proteinase.