ZiCo: a peptide designed to switch folded state upon binding zinc

We describe a novel approach to the design of a metal-triggered conformational switch. Specifically, two distinct protein-folding motifs were merged into one polypeptide sequence. The target structures were an alpha-helical coiled-coil trimer and zinc-bound monomer. Solution-phase spectroscopic, sedimentation, and binding studies confirmed the key aspects of the design. Both forms of the peptide were cooperatively folded, and the switch between them was reversible. This design process potentially presents a novel route to peptide-based biosensors.     

Triol protection with 6-benzoyl-3,4-dihydro-(2H)-pyran

6-Benzoyl-3,4-dihydro-(2H)-pyran will protect 1,2,3-triols such as glycerol as their corresponding spiro-[5-phenyl-3,6,8-trioxabicyclo[3.2.1]octane-4,2[prime or minute]-tetrahydropyran]s and 1,2,4-triols (less efficiently) as the corresponding trioxabicyclo[3.2.2]nonanes; the hexol mannitol is converted into the corresponding bis-protected product.     

13C n.m.r. spectroscopy: Comparison of the spectra of some dimeric Catharanthus alkaloids and their derivatives

The ¹³C n.m.r. spectra of some dimeric Catharanthus alkaloids are reported and assigned. Methods devised to aid in the assignment of resonances in complex molecules are described. The ¹³C n.m.r. spectra of several derivatives of vinblastine are discussed.     

Dynamical stability and pure thermodynamic phases

A notion of stability of dynamics under distant perturbations is introduced. It is demonstrated, for quasi-local systems, that the stability of an equilibrium state under the same perturbations implies the state is factorial, i.e. strongly clustering in space. We also characterize the set of perturbations necessary to ensure the equivalence of stability and factorialness.