Klaus Eckart

Amino acid sequence of Manduca sexta adipokinetic hormone elucidated by Combined Fast Atom Bombardment (FAB)/Tandem Mass Spectrometry

Combination of Fast Atom Bombardment Tandem Mass Spectrometry with Amino Acid Analysis assigns the amino acid sequence of the Manduca sexta adipokinetic hormone as pGlu-Leu-Thr-Phe-Thr-Ser-Ser-Trp-GlyNH2. Similarities and differences with other invertebrate hormones and with mammalian glucagon are discussed.

Metallorganische verbindungen der lanthanoide: XXXV. Bis(tetramethylethylendiamin)lithium tetrakis-t-butylluteta(III): synthese, molekülstruktur und reatives verhalten gegenüber α,β-ungesättigten carbonylverbindungen

Abstract LuCl3 reacts with t-butyllithium in the presence of ether and tetramethylethylene diamine (tmed) to form [Li(tmed)2][Lu(t-C4H9)4], the structure of which has been elucidated through complete X-ray analysis. The crystals are orthorhombic with a 20.995(9), b 18.310(7), c 9.527(2) A, space group P21ab, Z = 4, D(calcd) 1.17 g cm−3, R = 0.035, and 2471 observed reflections. The compound undergoes 1,2-addition to cinnamic aldehyde, benzalacetone, 1-phenylbutene-2-methyl-3-one, 2-methylbutene-3-one and cyclohexanone, respectively, to give after hydrolysis of the reaction mixture α-t-butyl-substituted enoles. The reaction products were identified by means of GC/MS methods.

Specific reciprocal methyl/hydrogen transfer reactions and hydrogen exchange processes between aryl rings in crowded ketone cation radicals☆

Abstract In distinct contrast to metastable triarylethenol cation radicals, the corresponding isomeric ketones not only show site-specific reciprocal methyl/hydrogen migration but, in addition, some of them undergo hydrogen exchange reactions between the various aryl rings prior to dissociation. A brief discussion is presented for H 2 O loss from ionized 1,2,2-trimesitylethanol and the gas-phase chemistry of the resulting trimesitylethene cation radical.

Generation and Interpretation of Fast Atom Bombardment Mass Spectra of Modified Peptides

Until recently the possibility of mass spectrometric investigations was limited by the volatility of the investigated compounds. Due to the high polarity and low volatility of peptides, derivatization was necessary to obtain volatile derivatives, but new difficulties like incomplete reactions and/or side reactions and fragmentation were involved, and last but not least, the time needed for the derivatization was considerable.