Robert W. Humble

Nmr Studies of Configuration and Conformation in N-Acyl-D-Ribosylamines

ABSTRACT Configurational assignments for a series of N-acyl-D-ribofuranosylamines have been established unequivocally using a set of NMR criteria. The conformation of the exo-cyclic substituents is determined.

Stereoselective Synthesis of N-(α- and β-Ribofuranosyl)-Formamtdes and Related Glycosyl Formamtdes - Precursors for Sugar Isocyantdes

Abstract Efficient stereospecific N-formylation of ribosylamine has been achieved, affording the α-anomer directly (by reaction with formic-acetic anhydride) and the β-anomer via the corresponding formamidine derivative (by reaction with dimethylformamide dimethyl acetal). Dehydration of the α-anomer gave the corresponding isocyanide without compromising the anomeric purity. The amidine route was extended to give the N-formyl derivatives of α-xylosylamine and α-arabinosylamine.

Phosphorylation of Some 5-Aminoimidazole Nucleosides to the 5’ -Phosphates Using a Phosphotransferase from Wheat

Abstract Several D-ribofuranosyl, D-xylofuranosyl and D-arabinofuranosyl 5-aminoimidazoles have been successfully phosphorylated to 5’ -phosphates using a phosphotransferase from wheat shoots and p-nitrophenylphosphate as a phosphate donor.

A Novel Synthesis of Mizoribine® and Related Nucleosides from Acyclic Precursors

Abstract Mizoribine® (4-carbamoyl-1-β-D-ribofuranosylimidazolium-5-olate)(13β) and its 4-cyano analogue (20) were synthesized by formation of a malonamide from 2,3-isopropylidene-D-ribosylamine and a malonic acid derivative followed by amination, cyclisation and deprotection steps.

Synthesis of Some 2-Alkylated-5-Aminoimidazoles Related to Intermediates in Purine Nucleotide de novo and Thiamine Biosynthesis

Abstract Routes to 2-alkylated-5-aminoimidazole nucleosides have been investigated in which the 2-substituent has up to 3 carbon atoms and capable of being interconverted into suitable oxy and 0x0 alkyl derivatives for use in enzyme inhibition and biochemical incorporation studies involving both purine nucleotide de novo and thiamine biosynthesis.

2-Deoxy-D-Ribofuranosylation of Ethyl 5-Aminoimidazole-4-Carboxylate by Biotransformation and Chemical Methods

Abstract In our studies aimed at the synthesis of inhibitors of enzymes involved in the de novo biosynthesis of purine nucleotides, the arabinosyl nucleoside (la), which is analogous to CAIR (lb), a central intermediate in the pathway, showed significant inhibition and substrate activities. We were therefore interested to synthesize the related 2-deoxy-D-ribosyl nucleotide (lc) for further enzymological studies.

Rapid Purification of a Bifunctional Protein Complex Possessing Phosphoribosylaminoimidazole Carboxylase (EC 4.1.1.21) and Phosphoribosylaminoimidazolesuccinocarboxamide Synthetase (EC 6.3.2.6) Activities

Previously reported partial purification protocols for the enzymes EC 4.1.1.21 and EC 6.3.2.6 have proved either unsuccessful in resolving the enzyme activities1, or have only considered one of the enzymes2,4,5,6. These procedures involve numerous precipitation and lengthy chromatographic steps, with a subsequent loss in activity, especially of EC 6.3.2.6 which is highly labile. In addition, it is difficult to ascertain the purity of the enzymes obtained by the previous workers, due either to the abscence of, or only limited electrophoretic evidence reported.