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Biomedical subjects

F Percheron

Publications and source records attributed to F Percheron.

At least 37 records · Page 2Linked to original sources
PubMed1985

Decreased serum beta-D-mannosidase activity in diabetic patients, in comparison with other glycosidases.

A study of four lysosomal glycosidases' activities was carried out on sera from 64 diabetic patients, which revealed important variations in comparison with the activities observed in sera of control subjects. Depending on the type of diabetes mellitus (I, insulin-dependent, or II, non-insulin-dependent), three activities were more or less increased: alpha-L-fucosidase, alpha-D-mannosidase, and N-acetyl-beta-D-glucosaminidase, in agreement with previously published results. Against that, the beta-D-mannosidase activity shows a highly significant decrease in sera from either diabetic type. Up to now, no suitable explanation has been found for these variations occurring in an unusual direction.

Acetylglucosaminidase↗
PubMed1985

Early monitoring of human renal transplantations by N-acetyl-beta-D-glucosaminidase isoenzyme activities in urines.

Monitoring of variations in N-acetyl-beta-D-glucosaminidase (NAG) urinary activity, following renal transplantation, has been proposed for the early diagnosis of rejection episodes. In this study, the measurement of urinary NAG-B activity was conducted as a complement to total NAG (A + B) measurement, which is normally used alone. Selective measurement of NAG-B activity is carried out after fixation of NAG-A on ion exchanger in test tubes. Results of NAG (A + B) activity confirm that the assay of urinary NAG is a useful indicator of rejection, but a positive correlation between NAG-B and NAG (A + B) activities was observed during the various complications which can occur after transplantation. The specific measurement of this isoenzyme does not, therefore, seem to provide additional information in the early monitoring of human renal transplantations. Apart from rejection episodes, other factors are likely to produce marked NAG-B excretion, e.g. gentamicin therapy.

Acetylglucosaminidase↗
PubMed1985

Inhibition of A and B N-acetyl-beta-D-glucosaminidase urinary isoenzymes by urea.

A urinary fraction which inhibits the activity of N-acetyl-beta-D-glucosaminidase (NAG) has been isolated and identified as being urea. Usually present in high concentration, urea appears to be the only urinary component responsible for the frequently observed urinary NAG inhibition. The inhibition of the two urinary NAG isoenzymes A and B is competitive with respective Ki values of about 70 mmol/l and 60 mmol/l. With routine assay conditions, it seems that a dilution of urine prior to enzyme assay is sufficient to abolish the inhibition of the two isoenzymes A and B by endogenous urea.

Acetylglucosaminidase↗
PubMed1984

Comparative study on cat allergens from fur and saliva.

The allergenic components of cat fur extract were localized in the molecular weight range 65,000-40,000 and had a pI of 3.9-5, except one with a more acid pI of 3.5. The fraction with a mean molecular weight of 65,000 contained proteins of pI 4.5-5 and mainly cat serum albumin. The fraction with a mean molecular weight of 40,000 showed two peaks of activity. One of them was associated with a protein of pI 3.5, and immunodiffusion analysis showed the presence of 'Cat Allergen One'. A comparative study on cat saliva showed that the allergenic activity was restricted to proteins of the same molecular weight range. 'Cat Allergen One' was present in the fraction of molecular weight 40,000.

Allergens↗
PubMed1983

On the specificity of the two forms of human serum alpha-L-fucosidase.

All normal sera exhibiting either normal or low activities contain two forms of alpha-L-fucosidase (F1 and F2). These two forms, isolated from either type of serum, have respectively similar properties, but the low-activity sera contain a major proportion of the thermolabile, less-acidic form, F1. The specificities for natural substrates (glycoproteins and oligosaccharides) and for synthetic fucosides have been studied. All types of alpha-L-fucosidase linkages (1,2; 1,3; 1,4 and 1,6) are split by the form F2. The specificity of the form F1 is more restricted. Only alpha(1,3) and some types of alpha(1,2) and alpha(1,4) fucosyl linkages are split.

Carbohydrate Conformation↗
PubMed1983

The chitin-degrading enzyme system of a Streptomyces species.

1. In the study of natural chitin metabolism by a strain of Streptomyces, we have separated by affinity chromatography the different extracellular chitinolytic enzymes synthetised by the microorganism. 2. N-acetylglucosaminidase (pHi = 3.6) with activity against the synthetic soluble derivatives from beta-D-N-acetylglucosamine, and against the chitobiose, with respectively pH optimum = 4.4-4.7 and 5.3 (mol. wt = 50,000). 3. N-acetylhexosaminidase (pHi = 8.5) with activity against M.U.G. 4. Chitinase (pHi = 4.25) with solubilizing activity against colloïdal chitin, and hydrolyzing activity against 3,4-dinitrophenylchitotetraoside, if the pH is 6 less than pH less than 10. (mol. wt 56,000). 5. Chitinases (pHi = 7.5 and 8.2) with activity against colloïdal chitin if the pH is 4.5 less than pH less than 9. (mol wt = 20,000).

Acetylglucosaminidase↗
PubMed1982

Identification and kinetic studies of an inducible mannokinase from a Streptomyces strain.

Crude extracts from cells of a Streptomyces strain isolated from a palm-grove soil and grown on different carbon sources showed a constitutive glucokinase. Specifically inducible kinase activity for mannose was found in cells grown on mannose or beta-D-mannan. The activity on mannose was due to a highly specific mannokinase (ATP:D-mannose 6-phosphotransferase, EC 2.7.1.7) which has been separated from the glucokinase by Ultrogel AcA 54 gel filtration chromatography. Initial velocity and inhibition product studies were carried out to investigate the reaction pathway. In the absence of products, reciprocal plots intersecting on the abscissas were observed when either mannose or ATP concentration was varied in the presence of several fixed concentrations of the non-varied substrate. Km values for mannose and Mg-ATP complex are 0.33 and 1.1 mM, respectively. In the product inhibition studies, mannose-6-P was observed to be competitive with mannose and non-competitive with Mg-ATP. The reverse was observed when ADP was used as inhibitor. These data are consistent with a random sequential Bi-Bi mechanism with two dead-end ternary complexes.

Adenosine Triphosphate↗
PubMed1982

[Perchlorosoluble glycoproteins and myocardial infarct: modifications of the carbohydrate moiety (author's transl)].

Protein, hexose, amino sugar and sialic acid levels were determined in the perchlorosoluble fraction of serum from patients with myocardial infarct. Patients have significantly elevated mean values for all components. The hexose/perchlorosoluble protein and amino sugar/perchlorosoluble protein ratios were not significantly different when compared in normal and patient sera but the sialic acid/perchlorosoluble protein ratio was higher in patients with myocardial infarct. This change in sialic acid content could be related to an increased sialylation of glycoproteins normally present in serum. Particularly, an orosomucoid fraction with a higher content in sialic acid than that of the normal glycoprotein has been identified.

Adolescent↗
PubMed1981

Properties of two forms of alpha-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.

Chromatography, Ion Exchange↗
PubMed1981

Transglycosylation reactions catalysed by two beta-mannanases.

By using [3H]mannobiose as a labelled acceptor, it was possible to demonstrate transfer reactions catalysed by two beta-mannanases, with mannotetraose and mannopentaose as substrates. The enzyme from Streptomyces transfers one mannose unit from the oligosaccharides, whereas the enzyme from fenugreek (Trigonella foenum-graecum) seeds is able to transfer oligomannose residues.

Mannans↗
PubMed1979

[Enzymatic induction during isoniazid therapy (author's transl)].

Enzyme induction by isoniazid was studied by urinary D-glucaric acid estimation in slow and fast acetylators. Isoniazid administration increases significantively the D-glucaric acid elimination in the two classes of patients. In fast acetylators, the glucaricaciduria increases regularly up to 1.8 fold the physiological level in 30 days. In slow acetylators, after a progressive elevation during 20 days, the glucaricaciduria reaches quickly a 3 fold increase after 30 days. When a classic inducer such as phenobarbital is administrated in association with isoniazid, induction is stimulated in the two groups of patients. The estimation of plasmatic free isoniazid seems to indicate that the acetylation rate of isoniazid is not on the dependance of the induction process when the drug is administrated alone. In contrast, this rate increases when the association isoniazid-phenobarbital is administrated to slow acetylators. Possible consequences on the hepatic toxicity of isoniazid are discussed.

Acetylation↗
PubMed1976

[alpha-L-Rhamnosidase from Fagopyrum esculentum: purification and some properties (author's transl)].

An alpha-L-rhamnosidase from the seeds of Fagopyrum esculentum (saracen corn) has previously been identified, and the effect of the enzyme on rhamnoisic bonds has been studied with various flavonoid glycosides. This alpha-L-rhamnosidase can be useful in structural studies, and a preliminary report of this study has appeared. The present paper describes the extensive purification of the enzyme and the determination of its properties. The purification involved extraction, ammonium sulfate fractionation and chromatography on Sephadex G 75, DEAE-Sephadex and Ultrogel AcA-44. The alpha-L-rhamnosidase was purified about 9600 fold and the final enzyme preparation was practically pure according to the criteria of disc electrophoresis. The molecular weight of this alpha-L-rhamnosidase, calculated from data obtained by disc gel electrophoresis and gel filtration, was about 70 000. Isoelectric focusing established the isoelectric point to be 3.7. The behaviour of the enzyme on a concanavalin-A-Sepharose column suggests the presence of residues resembling alpha-D-mannose or alpha-D-glucose in the protein. The various kinetic parameters, Kcat, Km and the Kcat/Km ratio have been determined at pH 5 on the following substrates: p-nitrophenyl-alpha-L-rhamnoside and rutinose (6-O-alpha-L-rhamnosyl-D-glucopyranose). All kinetics exhibit a Michaelian behaviour and the Km for the former substrate was 0.33 mM and for the latter, 2.2 mM. The Kcat/Km ratio corroborates the greater specificity of the enzyme for p-nitrophenyl-alpha-L-rhamnoside. L-Rhamnose, L-lyxose, 6-deoxy-D-glucose and methyl-alpha-D-mannoside were shown to behave strictly as competitive inhibitors of alpha-L-rhamnosidase activity; it seems that the methyl group of L-rhamnose is important for substrate binding to the enzyme.

Binding, Competitive↗
PubMed1976

[Purification and mechanism of action of a plant galactokinase].

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. Km's for galactose and for Mg/ATP2- complex were respectively 0.54 x 10-3 M and 5, 10-3 M. Galactose-1-phosphate is a competitive inhibitor of galactose while the inhibition for Mg-ATP2- is not a competitive one. The Mg-ADP complex is a non-competitive inhibitor of both galactose and Mg-ATP2-. Moreover, the Km of the enzyme for M-ATP2- 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-ATP2-, 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 C6 position for the binding on the enzyme.

Adenosine Triphosphate↗