Ulrich Niedballa

Nitroxyl compounds, and diagnostic media based thereon useful for enhancing NmR imaging

Diagnostic media suitable for NMR diagnoses contain compounds of Formula I ##STR1## wherein is a single bond or a double bond, X is the grouping --(CH2)n -- or , if is a single bond, also the grouping --NHCO(CH2)n -- wherein n means 0 to 4, m means the numbers 0, 1, or 2, R1 is an alkyl residue substituted by hydroxy groups, acyloxy groups and/or alkylidenedioxy groups, R2 has the same meanings as R1 or is a hydrogen atom or an alkyl residue, R3 and R4 are alkyl residues, and R5 and R6 are alkyl residues optionally substituted by hydroxy groups.

2′-O-methylcytidine 5′-diphosphate as substrate for polynucleotide phosphorylase from Escherichia coli

Abstract Polymerization de novo of 2′- O -methylcytidine 5′-diphosphate (CmDP) by polynucleotide phosphorylase from Escherichia coli in the presence of Mg 2+ was not observed, although a poor but significant phosphate exchange took place. Phosphate exchange was enhanced in the presence of either ApU or UDP. The copolymerization of a [ 3 H]UDP-[ 14 C]CmDP mixture was investigated. The copolymers formed were isolated by Sephadex chromatography, and the nucleotide ratio UMP to 2′- O -methylcytidine 5′-phosphate (CmMP) was estimated. Polynucleotide phosphorylase from E. coli in the presence of ApU polymerized CmDP to short oligonucleotides which were isolated and characterized.