We describe the synthetic route to ethylenediaminetetraacetic acid (EDTA) derivatives that can be attached to surface-exposed thiol functional groups of cysteine residues in proteins, via a methylthiosulfonate moiety that is connected in a stereochemically unique way to the C-1 carbon atom of EDTA. Such compounds can be used to align proteins in solution without the need to add liquid crystalline media, and are, therefore, of great interest for the NMR spectroscopic analysis of biomolecules. The binding constant for the paramagnetic tag to lanthanide ions was determined by measuring luminescence. For the Tb(+3)-ligand complex, a K(b) value of 6.5 x 10(17) M(-1) was obtained. This value is in excellent agreement with literature values for the related EDTA compound. In addition, it could be shown that there is no significant reduction in the luminescence intensity upon addition of a 10(4) excess of Ca2+ ions, indicating that this paramagnetic tag is compatible with buffers containing high concentrations of divalent alkaline earth ions.

Zusammenfassung: Es wird eine verbesserte Methode zur Darstellung von großen Mengen reiner, kristallisierter Glycerinaldehyd-3-phosphat-Dehydrogenase aus Bäckerhefe beschrieben. Die Verbesserungen bestehen in der Verwendung von 5mM EDTA in allen Lösungen und von schwermetallfreiem Ammoniumsulfat für die Kristallisation. Nucleinsäuren werden mit Protaminsulfat und gebundene Nucleotide mit Aktivkohle entfernt. Das Präparat zeichnet sich durch bisher unerreichte Werte der spezifischen Aktivität sowie des Verhältnisses £280/^260 aus, die durch weitere Reinigungsoperationen nicht mehr verändert werden. Die elektrophoretische und histochemische Analyse Summary: An improved method is reported for the preparation of large quantities of pure, crystalline glyceraldehyde-3-phosphate dehydrogenase from baker's yeast. The improvements consist of 1) inclusion of 5mM EDTA in all solutions, 2) crystallization with ammonium sulfate of low heavy metal content, 3) removal of nucleic acids by precipitation with protamine sulfate, and 4) removal of bound nucleotides with washed charcoal. The specific activity and the ratio of £280/^260 of the preparation exceed the values previously reported. They did not change subsequently in further attempts at purification. Electrophoresis and histochemical analysis of the In vorangegangenen Arbeiten 1 » 2 wurde der Mechanismus

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This article presents a proposal on how the European Union’s regulatory framework on genetically modified (GM) plants should be reformed in light of recent developments in genomic plant breeding techniques. The reform involves a three-tier system reflecting the genetic changes and resulting traits of GM plants. The article is intended to contribute to the ongoing debate over how best to regulate plant gene editing techniques in the EU.

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