Phosphoenolpyruvate: An end to hand-waving.

The conversion of phosphoenolpyruvate (PEP) in glycolysis is coupled with the formation of ATP. This note discusses the origin of the energy required for ATP formation as arising from redistribution of energy in PEP when compared with its precursor, 2-phosphoglycerate.

The Elbs and Boyland-Sims peroxydisulfate oxidations.

This paper reviews the recent literature on the title reactions and updates a 1988 review.

Cleavage and cross-linking of proteins with osmium (VII) reagents.

The specific cleavage of proteins following reaction with osmium tetroxide is slowed down by tertiary amines which are known to be good ligands for osmium. Bidentate ligands are more effective than monodentate ligands. These same ligands also promote an intermolecular cross-linking reaction.

Resolution of D- and L-galactose peracetates as their bis(ethyl L-lactate) acetals by gas-liquid chromatography.

Reaction between ethyl L-lactate and each of a pair of sugar enantiomers, the peracetylated D-galactose and L-galactose diethyldithioacetals, produced two acyclic diasterioisomers. They could be separated by conventional gas-liquid chromatography. The corresponding fucose diastereomers were also separated. This process should make it possible to develop a general analytical method by which small amounts of enantiomeric sugars can be identified and their quantities measured.

A new synthesis of sucrose 6'-phosphate.

Sucrose 6'-phosphate (3) is the key intermediate for sucrose (1) synthesis in plants [1]. It has recently become commercially available at ca. $1500/g (Sigma). The only chemical synthesis is that of Buchanan et al. [2]. This six-step procedure, while unambiguous, gives an overall yield of only ca. 6%. We describe here a simplified route (2 steps) with an unoptimized yield of ca. 15%. Our strategy was to use a phosphorylation reagent selective for primary hydroxyl groups and thus to avoid the necessity for blocking all of the secondary ones. Sowa and Ouchi [3] described a suitable system which they used very effectively for the synthesis of 5'-nucleotides from unprotected nucleosides. We applied this reagent to 2,1':4,6-di-O-isopropylidenesucrose (2) [4] in which the only unprotected primary hydroxyl group is that at the 6'-position (Scheme 1). The identity of the product was established by comparison of its rotation with the literature value and by the correspondence of its 1H and 13C NMR spectra with those of an authentic sample synthesized by Buchanan's method (Sigma) 1H assignments were made with the help of the assignments of du Penhoat et al. [5] for sucrose and the results of a one-bond H-C COSY experiment (Fig. 1). The 13C spectrum showed that all of the resonances were shifted downfield by ca. 0.5 ppm as compared with sucrose [6] except for the C-5' doublet which was shifted upfield by 0.5 ppm and the C-6' doublet which was shifted downfield by 2.2 ppm (Table 1).

Synthesis of beta-L-fucopyranosyl phosphate and L-fucofuranosyl phosphates by the MacDonald procedure.

Fusion of beta-L-fucopyranose tetraacetate with phosphoric acid for 1 min at 50 degrees gives a 9:1 anomeric mixture of the alpha- and beta-pyranosyl phosphates. Longer fusion times give the alpha-anomer exclusively. The L-fucofuranose tetraacetates were synthesized for the first time by acetolysis of methyl-2,3,5-tri-O-acetyl-beta-L-fucofuranoside. Fusion of the furanose tetraacetates with phosphoric acid gave a mixture of the fucofuranosyl phosphates in which the beta-anomer predominated (beta/alpha= 2.4). Anomeric pairs in the fucofuranose series appear to be distinguishable by the chemical shift of the C-6 methyl protons, as already shown by Sinclair and Sleeter in the pyranose series.

The bacterial oxidation of nicotinic acid. N-formylmaleamic and N-formylfumaramic acids.

N-Formylmaleamic acid, a probable intermediate in the bacterial metabolism of nicotinic acid, has been synthesized by photoisomerization of its trans isomer, N-formylfumaramic acid. The compound previously reported to be N-formylmaleamic acid has been shown to be N-formylfumaramic acid.