Die Guajakprobe auf Blut

Analytical and Bioanalytical Chemistry -     

Charge‐Induced Unzipping of Isolated Proteins to a Defined Secondary Structure

Here we present a combined experimental and theoretical study on the secondary structure of isolated proteins as a function of charge state. In infrared spectra of the proteins ubiquitin and cytochrome c, amide I (C=O stretch) and amide II (N–H bend) bands can be found at positions that are typical for condensed‐phase proteins. For high charge states a new band appears, substantially red‐shifted from the amide II band observed at lower charge states. The observations are interpreted in terms of Coulomb‐driven transitions in secondary structures from mostly helical to extended C₅‐type hydrogen‐bonded structures. Support for this interpretation comes from simple energy considerations as well as from quantum chemical calculations on model peptides. This transition in secondary structure is most likely universal for isolated proteins that occur in mass spectrometric experiments.     

New nuclides: Neptunium-243 and neptunium-244

We have observedγ-rays following the β^?-decay of²⁴³Np and²⁴⁴Np after chemical isolation of neptunium isotopes from the products of the reaction of 835 MeV¹³⁶Xe with²⁴⁴Pu. The ground-state of 1.85-min²⁴³Np hasJ=5/2. The decay of 2.29-min²⁴⁴Np (probableJ ^π=7^?) populates high-spin members of the ground state rotational band in²⁴⁴Pu.