Radioactive sedoheptulose 7-phosphate was shown to label specifically the L-glycero-D-mannoheptose residues of the lipopolysaccharide of a transketolase-negative mutant of Salmonella typhimurium. Phosphoheptose isomerase, the first enzyme in the proposed pathway of heptose biosynthesis, was shown to catalyze the reaction: sedoheptulose 7-phosphate --+ D-glycero-D-mannoheptose 7-phosphate. This ...

The transketolase (TKT) enzyme in Mycobacterium tuberculosis represents a novel drug target for tuberculosis treatment and has low homology with the orthologous human enzyme. Here, we report on the structural and kinetic characterization of the transketolase from M. tuberculosis (TBTKT), a homodimer whose monomers each comprise 700 amino acids. We show that TBTKT catalyses the oxidation of dono...

Activation of the coenzyme ThDP was studied by measuring the kinetics of deprotonation at the C2 carbon of thiamin diphosphate in the enzymes pyruvate decarboxylase, transketolase, pyruvate dehydrogenase complex, pyruvate oxidase, in site-specific mutant enzymes and in enzyme complexes containing coenzyme analogues by proton/deuterium exchange detected by 1H-NMR spectroscopy. The respective dep...

In animal experiments, hippocampal neurogenesis and the activity of thiamine-dependent transketolase decrease markedly under conditions of thiamine deficiency. To further investigate the effect of thiamine deficiency on the proliferation of hippocampal progenitor cells (HPCs) and the potential mechanisms involved in this effect, we cultured HPCs in vitro in the absence of thiamine and found tha...

The transformation of pentose to hexoses was first observed by Dische (1) in hemolysates of red blood cells. Glucose 6-phosphate was shown to accumulate when ribose S-phosphate was incubated in a crude enzyme preparation from liver (2), and fructose 6-phosphate was identified by Clock (3) as the first product of the pentose-hexose transformation. It was shown by de la Haba and Racker (4) that t...

In this semiautomated method, an AutoAnalyzer II is used to measure the enzymic production of glyceraldehyde 3-phosphate in hemolysates, to assay erythrocyte transketolase (EC 2.2.1.1) activity. Hemolysate and indicator reactions are separated by dialysis to eliminate hemoglobin interference and increase sensitivity. Internal standards of glyceraldehyde 3-phosphate in hemolysate carriers were q...

INTRODUCTION The activity of erythrocyte transketolase induced by thiamine pyrophosphate and normalized to age of the patient is a marker of thiamine metabolism disturbances with pathological consequences in the central and peripheral nervous system. The measurement of erythrocyte transketolase activity enables evaluation of the thiamine status and therapeutic decisions in the disorders of the ...

The determination of blood transketolase before and serially after thiamine administration, and the response of clinical symptomatology after thiamine are reported in two normomagnesaemic patients and one hypomagnesaemic patient with acute Wernicke-Korsakoff encephalopathy. The response of the depressed blood transketolase and the clinical symptoms was retarded in the hypomagnesaemic patient. C...

Erythrocyte transketolase activity and the effect of adding thiamine pyrophosphate (% thiamine pyrophosphate effect) were measured in 111 subjects suspected to suffer from Leigh's disease (subacute necrotising encephalomyelopathy). From clinical evidence these subjects were divided into five groups: (1) necropsy-proved cases of subacute necrotising encephalomyelopathy, (2) cases positive for ur...