Marie-José Foglietti

Synthesis of azasugars as potent inhibitors of glycosidases

A series of enantiomerically pure azasugars (2,5-dideoxy-2, 5-imino-D-mannitol, 1-deoxynojirimycin, 1-deoxymannojirimycin, and related compounds) was synthesized from D-mannitol via aminoheterocyclization of C2-symmetric bis-epoxides and subsequently followed by ring isomerization in few cases. These compounds have been evaluated as inhibitors of several glycosidases (alpha- and beta-D-glucosidases, alpha-D-mannosidase and alpha-L-fucosidase). Inhibition studies indicate notably that the polyhydroxylated azepanes are inhibitors of glycosidases, with Ki in the micromolar range.

Synthesis of thiosugars as weak inhibitors of glycosidases

Abstract A series of enantiomerically pure thiosugars (1,6-dideoxy-1,6-thio-D-mannitol or L-iditol, 1,5-dideoxy-1,5-thio-L-gulitol or D-glucitol and 2,5-dideoxy-2,5-thio-L-iditol or D-mannitol, and their corresponding sulfoxide or sulfone) was synthesized via thiocyclization of C2-symmetric bis-epoxides, and subsequently followed by ring isomerization in few cases. These compounds have been evaluated as inhibitors of several glycosidases (α- and β-D-glucosidases, α-D-mannosidase and α-L-fucosidase).

Chiral 5-Methyl-trihydroxypyrrolidines—Preparation from 1,2-Oxazines and Glycosidase Inhibitory Properties

Abstract Chemical transformations of chiral 1,2-oxazines 4, 5 gave the 2,5,6-trideoxy-2,5-imino d -alditols 12b, 13b in the d -altritol and d -talitol series, respectively. Basic aldehyde epimerisation led to the d -allitol isomer 15b. Compound 12b is a potent α- l -fucosidase and α- d -galactosidase inhibitor.

Fractionnement d'une préparation cellulasique de trichoderma viride par chromatographie d'affinité sur cellulose réticulée

Abstract Affinity chromatography of a cellulase complex from Trichoderma viride on cross-linked cellulose A procedure involving affinity chromatography on cross-linked cellulose was developed for separating enzymatic components of a cellulase complex from Trichoderma viride. The exoglucanases [β-(1 → 4)- d -glucane cellobiohydrolase and cellobiase] passed through the column in the equilibrating buffer, whereas the endoglucanases were fixed in the same conditions. Five endo-β(1 → 4)-glucanases were fractionated by elution with stepwise increasing concentrations of carboxymethylcellulose added to the buffer. These endoglucanases were differentiated by their substrate specificities and by their reaction pattern toward carboxymethylcellulose, cellulose, insoluble cellodextrins and oligosaccharides.

Purification d'α-amylases par chromatographie d'affinité sur amidon réticulé

Summary Affinity chromatography on cross-linked starch affords a simple and rapid procedure for α-amylases (EC 3.2.1.1.) purification. When starch is cross-linked in alkaline medium by epichlorhydrin in the conditions described, the insoluble polysaccharide obtained is able to retain specifically the α-amylase which is then eluted with 2M maltose solution. α-amylase can be obtained in a pure form with a 60 per cent yield. The exoenzyme β-amylase (EC 3.2.1.2) is not retained by the support and is eluted with other contaminant proteins. Therefore, this procedure allows the separation of the endo- and exoamylase activities.

Microheterogeneity of α1-acid glycoprotein: variation during the menstrual cycle in healthy women, and profile in women receiving estrogen-progestogen treatment

The concentration of alpha 1-acid glycoprotein (AGP) was measured in sera from 23 women, 14 pregnant women, 10 women receiving estrogen-progestogen treatment and 12 men. All sera were further subjected to crossed affino-immunoelectrophoresis with addition of conA in the first dimension and alpha-methylglucopyranoside in the second dimension. The distribution of AGP into three microheterogeneity forms, which were the result of this analysis, was estimated by measuring the area under the precipitation curve. The microheterogeneity patterns of AGP in the five groups were analysed from each other. An augmentation of the non reactive form is seen in women in the first part of the cycle and in women receiving estrogen-progestogen treatment compared with the three others groups. The pattern obtained in this latter group is similar to that observed in pregnant women (34 weeks) by several authors.

Purification et mécanisme d'action d'une galactokinase végétale

Summary The previously described galactokinase from Fenugreek seeds, has been purified by affinity chromatography on a column of galactosamine-CH Sepharose. This material ensures a more specific fixation than does ATP-Sepharose. A 400 fold purification was achieved in a single step, with a 80 per cent yield. K m s for galactose and for Mg-ATP 2− complex were respectively 0.54 × 10 −3 M and 5.10 −3 M. Galactose-1-phosphate is a competitive inhibitor of galactose while the inhibition for Mg-ATP 2− is not a competitive one. The Mg-ADP complex is a non-competitive inhibitor of both galactose and Mg-ATP 2− . Moreover, the K m of the enzyme for Mg-ATP 2− complex is modified when 2-deoxy- and 6-deoxy-galactose are used instead of galactose. These results are consistent with an ordered sequential mechanism for this galactokinase : galactose binds to the enzyme before Mg-ATP 2− , and galactose-1-phosphate is the last reaction product liberated. The affinity of the kinase for 6-deoxygalactose is lower than for 2-deoxygalactose. This observation reveals the importance of the hydroxyl in C 6 position for the binding on the enzyme.

Mammalian β-D-mannosidase and β-mannosidosis

Abstract Lysosomal β- d -mannosidase is the last exoglycosidase involved in the sequential degradation of the N-glycosylproteins glycans. Research on this enzyme was restricted before the discovery of its hereditary deficiency, first in goat (1981) and later in man (1986). We describe the biochemical aspects of these β-mannosidoses and the properties of the β-mannosidases of mammalian origin. Our own results concerning human enzyme (from kidney and urine, seminal plasma and blood cells) suggest that, apart from the case of the inherited disease, β-mannosidase may become a useful tool in otherpathologies.

Properties of two forms of α-l-fucosidase isolated from normal human sera with low and high enzymatic activity

Studies on human alpha-L-fucosidase were performed on normal and low activity sera. After DEAE-Sephacel chromatography, two major forms of enzyme have been characterized in both types of sera. These enzymatic forms were different with respect to their thermostability and electrofocusing behaviour. The less acidic form (I) was thermolabile. In contrast, the more acidic one (II) was thermostable. But the forms I and II had respectively similar properties when isolated from either normal or low activity sera. These results suggest the presence in both types of sera of two major forms of alpha-L-fucosidase but in variable proportions. The low activity sera contained a major proportion of the thermolabile less acidic form when compared with normal activity sera.

Microheterogeneity of α1-acid glycoprotein in healthy elderly subjects: Patterns obtained by crossed affino-immunoelectrophoresis

Total serum alpha 1-acid glycoprotein (AGP) concentration and concanavalin A-dependent microheterogeneity were studied in 31 healthy elderly subjects (18 men, 13 women, 71 to 76 yr old). Crossed affino-immunoelectrophoresis (CAIE) revealed three microheterogeneity variants of AGP: non-reactive, weakly reactive and strongly reactive with ConA. Two patterns were found in both elderly men and women, i.e. a normal pattern and one with an increase in the non-reactive form. Mean serum AGP levels in the elderly subjects with slightly higher than in a reference group of younger subjects. The Con A non-reactive form of AGP was increased in 42% of the elderly population. An increase in the non-reactive form of AGP in CAIE should be considered as general expression of chronic inflammation which is of no clinical relevance.