A series of 36 linear and cyclic beta- and gamma-peptides consisting of as few as two, and as many as 15 residues, was offered as substrates to 15 commercially available proteases of bacterial, fungal, and eukaryotic origin, including a beta-lactamase and amidases, as well as most vigorous, nonspecific proteases, such as the 20S proteasome from human erythrocytes. For comparison, an alpha-eicosapeptide and standard substrates of the proteolytic enzymes were included in the investigation. Under conditions of complete cleavage of the alpha-peptide within 15 min the beta- and gamma-peptides were stable for at least 48 h. Inhibition studies with seven beta- and gamma-peptides and alpha-chymotrypsin show that the residual enzyme activity toward succinyl-Ala-Ala-Pro-Phe-p-nitroanilide is unchanged within experimental error after incubation for 15 min with the peptide analogues. Thus, beta- and gamma-peptides with proteinogenic side chains, that is, consisting of the singly or doubly homologated natural alpha-amino acids (one or two CH(2) groups inserted in the backbone of each residue), are completely stable to common proteases, without inhibiting their normal activity (as demonstrated for alpha-chymotrypsin). This proteolytic stability of peptides built of homologated amino acids is a prerequisite for their potential use as drugs.

fi-Hexapeptides 1-5 and a 8-dodecapeptide 6 with sequences containing two different types of fi-amino acids (aliphatic proteinageous side chains in the 2-or in the 3-position) have been prepared. CD (Fig. f) and NMR measurements indicate that, with one exception, the secondary structures formed by these new 8-peptides differ from those of isomers studied previously. Detailed NMR analysis of the 8-hexapeptide 5 (with alternating fiZ,fi3-building blocks) and molecular-dynamics simulations have produced a minimum energy conformation (Fig. 2,b) which might be described as a novel irregular helix containing ten-and twelve-membered H-bonded rings. This demonstrates the great structural variability of fi-peptides, since three different helical secondary structures have been discovered to date. ' ) 3,Part of the projected Ph. D. theses of K.G. and ZH., ETH-Zurich.

Driving innovation and creativity has relied heavily on new information technologies in the last decade. Human capital has certainly had its importance, but how to coordinate human capital in order to push productivity in research and development without compromising individual initiative is still not well understood. In this paper, we provide results showing that geometry of workspace has indeed an impact on communication patterns and may thus be used as a means to drive both innovation and efficient research. In order to be creative, new knowledge has to be created. Communication facilitates knowledge creation. We try to close the bridge between areas of creation of tacit knowledge and transfer of knowledge highlighted by authors like Nonaka, Takeuchi, Konno, von Krogh and von Hippel with the area of communication patterns pioneered by Allen, Hatch, and Stryker, by considering face-to-face (FTF) communication as a first step for socialization, socialization as a means for knowledge creation. In this article, we compare two different office environments within the same site, same activity, same hierarchical level and same company: a traditional cell office area and a new multi-space office, used by people who used to work in cell offices. We observed FTF communication patterns during 120 h in two areas and measured over 2,000 communication events. We found that people communicate three times more often in a multi-space area than in a cell-space area. We also found that the mean duration of communication events decreased from 9 to 3 min when transferring collaborators from a cell-space to a multi-space. Finally time spent without communication increased from 5% to 29% when going from cell-offices to multi-space areasleaving more time for people to work and think on their own. And we found that most communication events during work time in the multi-space took place at the work place and seldom or never in soft sitting areas installed for the purpose of communication.

This result is in agreement with the observation of P. Heiinbach and H. Hey that butadiene is liberated during the catalytic rearrangement of DVCB to COD and VCHt7].

A consortium of microorganisms was established that was able to grow with the beta-tripeptide H-beta-HVal-beta-HAla-beta-HLeu-OH, with the beta-dipeptide H-beta-HAla-beta-HLeu-OH, and with the beta-amino acids H-beta-HAla-OH, H-beta-HVal-OH, and H-beta-HLeu-OH as the sole carbon and energy sources. This growth was achieved after several incubation-transfer cycles with the beta-tripeptide as the substrate. During degradation of the beta-tripeptide H-beta-HVal-beta-HAla-beta-HLeu-OH, the temporary formation of a metabolite was observed. The metabolite was identified as the beta-dipeptide H-beta-HAla-beta-HLeu-OH by nuclear magnetic resonance spectroscopy and mass spectrometry. This result indicates that in the course of the degradation of the beta-tripeptide, the N-terminal beta-HVal residue was cleaved off by a not yet known mechanism. During the subsequent degradation of the beta-dipeptide, formation of additional metabolites could not be detected. The growth-yield coefficients Y(x/s) for growth on the beta-di- and beta-tripeptide both had a value of 0.45. When a 1:1 mixture of the beta-tripeptide and the corresponding alpha-tripeptide H-Val-Ala-Leu-OH was added to the enrichment culture, the alpha-peptide was completely utilized in six days and thereafter growth of the culture stopped. This result indicates that even in beta-peptide enrichment cultures, alpha-peptides are the preferred substrates. Our experiments clearly show for the first time that beta-peptides and beta-amino acids are amenable to biodegradation and that a microbial consortium was able to utilize these compounds as sole carbon and energy sources. Furthermore, the preparation of beta-amino acids, of derivatives thereof, and of beta-di- and beta-tripeptides is described.