scholarly journals Determination of inorganic sulphate in studies on the enzymic and non-enzymic hydrolysis of carbohydrate and other sulphate esters

1961 ◽  
Vol 78 (2) ◽  
pp. 312-319 ◽  
Author(s):  
K S Dodgson
Keyword(s):  
Enzymic Hydrolysis ◽  
Inorganic Sulphate ◽  
Hydrolysis Of

scholarly journals The hydrolysis of glycosyl fluorides by glycosidases. Determination of the anomeric configuration of the products of glycosidase action

1971 ◽  
Vol 123 (4) ◽  
pp. 607-611 ◽  
Author(s):  
J. E. G. Barnett
Keyword(s):  
Glucose Oxidase ◽  
Galactose Oxidase ◽  
Coffee Bean ◽  
Enzymic Hydrolysis ◽  
Initial Product ◽  
Rapid Assay ◽  
Anomeric Configuration ◽  
Ph Stat ◽  
Hydrolysis Of

The enzymic hydrolysis of glycosyl fluorides is conveniently followed by using a pH-stat. Reactions involving glucosyl or galactosyl fluorides can also be followed by using glucose oxidase or galactose oxidase respectively. The pH-stat allows the rapid assay of intestinal α-glucosidase in crude homogenates. Use of glycosyl fluorides as substrates for glycosidases facilitates the polarimetric or g.l.c. determination of the anomeric nature of the initial product of hydrolysis. Hydrolysis by fungal amyloglucosidase proceeds with inversion of configuration whereas that by yeast and rat intestinal α-glucosidase, coffee-bean α-galactosidase and almond emulsin β-glucosidase proceeds with retention of configuration. β-d-Glucopyranosyl azide was not a detectable substrate for almond emulsin β-d-glucosidase.

scholarly journals The acid and enzymic hydrolysis of O-acetylated sialic acid residues from rabbit Tamm–Horsfall glycoprotein

1972 ◽  
Vol 129 (3) ◽  
pp. 683-693 ◽  
Author(s):  
A. Neuberger ◽  
Wendy A. Ratcliffe
Keyword(s):  
Sialic Acid ◽  
Vibrio Cholerae ◽  
Clostridium Perfringens ◽  
Slow Rate ◽  
Alkaline Treatment ◽  
Side Chain ◽  
Hydroxyl Groups ◽  
Enzymic Hydrolysis ◽  
Hydrolysis Of

Rabbit Tamm–Horsfall glycoprotein and bovine submaxillary glycoprotein were both found to contain sialic acid residues which are released at a slow rate by the standard conditions of acid hydrolysis. These residues are also resistant to neuraminidases from Vibrio cholerae and Clostridium perfringens. This behaviour was attributed to the presence of O-acetylated sialic acid, since the removal of O-acetyl groups by mild alkaline treatment normalized the subsequent release of sialic acid from rabbit Tamm–Horsfall glycoprotein by acid and by enzymic hydrolysis. Determination of the O-acetyl residues in rabbit Tamm–Horsfall glycoprotein indicated that on average two hydroxyl groups of sialic acid are O-acetylated, and these were located on the polyhydroxy side-chain of sialic acid or on C-4 and C-8. These findings confirm the assumption that certain O-acetylated forms of sialic acid are not substrates for bacterial neuraminidases. Several explanations have been suggested to explain the effect of O-acetylation of the side-chain on the rate of acidcatalysed hydrolysis of sialic acid residues.

PREGNANETRIOL IN URINE: DETERMINATION AS A 17-KETOGENIC STEROID

1959 ◽  
Vol XXXII (IV) ◽  
pp. 596-605 ◽  
Author(s):  
R. Morris
Keyword(s):  
Congenital Adrenal Hyperplasia ◽  
Silica Gel ◽  
New Method ◽  
Adrenal Hyperplasia ◽  
Enzymic Hydrolysis ◽  
Normal Individuals ◽  
Hydrolysis Of

ABSTRACT A new method has been described for the determination of pregnanetriol in urine. It depends on the oxidation of pregnanetriol glucuronide to aetiocholanolone and its measurement as a Zimmermann chromogen after chromatography on silica gel. The method was applied to the urine from normal individuals and patients with congenital adrenal hyperplasia and the results were compared with a method using enzymic hydrolysis of the steroid conjugate.

The determination of egg in certain foods by enzymic hydrolysis of the phospholipids

The Analyst ◽  
1959 ◽  
Vol 84 (998) ◽  
pp. 281 ◽  
Author(s):  
C. B. Casson ◽  
F. J. Griffin
Keyword(s):  
Enzymic Hydrolysis ◽  
Hydrolysis Of

A METHOD FOR THE DETERMINATION OF VERY SMALL AMOUNTS OF OESTRONE IN HUMAN URINE

1960 ◽  
Vol 20 (4) ◽  
pp. 331-338 ◽  
Author(s):  
J. B. BROWN ◽  
H. A. F. BLAIR
Keyword(s):  
Sensitivity And Specificity ◽  
Methyl Ether ◽  
Human Urine ◽  
New Method ◽  
Enzymic Hydrolysis ◽  
Purification Step ◽  
Acidic Fraction ◽  
Hydrolysis Of ◽  
Alkaline Carbonate

SUMMARY A purification step involving separation of the ketonic fraction through the Girard complex has been incorporated in an earlier method for estimating urinary oestrogens. The new method, which measures oestrone only, involves acid or enzymic hydrolysis of the urine, extraction with ether, removal of the acidic fraction with alkaline carbonate solution, evaporation of the ether, separation of the ketonic fraction through the Girard complex, saponification, methylation, and chromatography on alumina columns. The oestrone methyl ether present in the final extract is measured by a semi-micro modification of the Kober reaction, which, with the larger volume of urine processed, increases the sensitivity of the estimation ninefold. This increase in sensitivity is made possible by the purification achieved in the new method, and fractions of 1 μg oestrone/24 hr urine can be measured. The reliability of the new method has been investigated and data concerning its accuracy, precision, sensitivity and specificity are presented. By comparison with the new method, the earlier method gives overestimates of approx. 0.9 μg oestrone/24 hr urine.

scholarly journals Investigation of ribonuclease-catalysed kinetics by a micro-calorimetric method

1976 ◽  
Vol 153 (1) ◽  
pp. 89-91 ◽  
Author(s):  
M Tribout ◽  
S Paredes ◽  
J Léonis
Keyword(s):  
Ribonuclease A ◽  
Calorimetric Method ◽  
Published Data ◽  
Enzymic Hydrolysis ◽  
Cyclic Phosphates ◽  
Hydrolysis Of ◽  
Cyclic Cmp ◽  
Step Mechanism ◽  
Good Agreement

A rapid micro-calorimetric method for the simultaneous determination of the Michaelis-Menten parameters and the enthalpy of enzymic reactions is developed. The hydrolysis of 2‘: 3’-cyclic CMP by ribonuclease A is studied to test the proposed method; values obtained are in good agreement with already published data. Enzymic hydrolysis of yeast RNA, unlike that of cyclic phosphates, is shown to be endothermic. This result is explained by the two-step mechanism of this reaction.

DETERMINATION OF MICRO-AMOUNTS OF 5β-PREGNAN-3α-OL-20-ONE IN URINE USING INFRARED-SPECTROMETRY

1962 ◽  
Vol 41 (2) ◽  
pp. 234-246 ◽  
Author(s):  
H. J. van der Molen
Keyword(s):  
Infrared Spectrum ◽  
Quantitative Determination ◽  
Acid Hydrolysis ◽  
Chromatographic Separation ◽  
Pure Form ◽  
Infrared Spectrometry ◽  
Hydrolysis Of

ABSTRACT A procedure for the quantitative determination of 5β-pregnan-3α-ol-20-one in urine is described. After acid hydrolysis of the pregnanolone-conjugates in urine, the free steroids are extracted with toluene. Pregnanolone is isolated in a pure form as its acetate; after chromatographic separation of the free steroids on alumina, the fraction containing pregnanolone is acetylated and rechromatographed on alumina. Quantitative determination of the isolated pregnanolone-acetate is carried out with the aid of the infrared spectrum recorded by a micro KBr-wafermethod. The reliability of the method under various conditions is discussed under the headings, specificity, accuracy, precision and sensitivity. It is possible to determine 30–40 μg pregnanolone in a 24-hours urine portion with a precision of 25%.

EINE CHEMISCHE METHODE ZUR BESTIMMUNG VON 16-EPI-ÖSTRIOL IM URIN DES MENSCHEN

1963 ◽  
Vol 44 (1) ◽  
pp. 47-66 ◽  
Author(s):  
W. Nocke ◽  
H. Breuer
Keyword(s):  
Melting Point ◽  
Phosphoric Acid ◽  
Aqueous Alkali ◽  
Percentage Error ◽  
Organic Layer ◽  
Maximum Percentage ◽  
Chemical Determination ◽  
Routine Assay ◽  
Hydrolysis Of

ABSTRACT A method for the chemical determination of 16-epi-oestriol in the urine of nonpregnant women with a qualitative sensitivity of less than 0.5 μg/24 h is described. The separation of 16-epi-oestriol and oestriol is accomplished by converting 16-epi-oestriol into its acetonide, a reaction which is stereoselective for cis-glycols and therefore not undergone by oestriol as a trans-glycol. Following partition between chloroform and aqueous alkali, the acetonide of 16-epi-oestriol is completely separated with the organic layer whereas oestriol as a strong phenol remains in the alkaline phase. 16-epi-oestriol is chromatographed on alumina as the acetonide and determined as a Kober chromogen. This procedure can easily be incorporated into the method of Brown et al. (1957 b) thus making possible the simultaneous routine assay of oestradiol-17β, oestrone, oestriol and 16-epi-oestriol from one sample of urine. The specificity of the method was established by separation of 16-epi-oestriol from nonpregnancy urine as the acetonide, hydrolysis of the acetonide by phosphoric acid, isolation of the free compound by microsublimation and identification by micro melting point, colour reactions and chromatography. The accuracy of the method is given by a mean recovery of 64% for pure crystalline 16-epi-oestriol when added to hydrolysed urine in 5–10 μg amounts. The precision is given by s = 0.24 μg/24 h. For the duplicate determination of 16-epi-oestriol the qualitative sensitivity is 0.44 μg/24 h, the maximum percentage error being ± 100% The quantitative sensitivity (±25% error) is 1.7 μg/24 h.

INDIREKTE PAPIERCHROMATOGRAPHISCHE METHODE ZUR BESTIMMUNG DER HARNOESTROGENE

1961 ◽  
Vol 38 (4) ◽  
pp. 545-562 ◽  
Author(s):  
L. Kecskés ◽  
F. Mutschler ◽  
I. Glós ◽  
E. Thán ◽  
I. Farkas ◽  
...  
Keyword(s):  
Pregnant Women ◽  
Granulosa Cell ◽  
Iron Content ◽  
List Type ◽  
Granulosa Cell Tumour ◽  
Hydrolysis Of ◽  
Phenol Fraction ◽  
Qualitative Determination

ABSTRACT 1. An indirect paperchromatographic method is described for separating urinary oestrogens; this consists of the following steps: acidic hydrolysis, extraction with ether, dissociation of phenol-fractions with partition between the solvents. Previous purification of phenol fraction with the aid of paperchromatography. The elution of oestrogen containing fractions is followed by acetylation. Oestrogen acetate is isolated by re-chromatography. The chromatogram was developed after hydrolysis of the oestrogens 'in situ' on the paper. The quantity of oestrogens was determined indirectly, by means of an iron-reaction, after the elution of the iron content of the oestrogen spot, which was developed by the Jellinek-reaction. 2. The method described above is satisfactory for determining urinary oestrogen, 17β-oestradiol and oestriol, but could include 16-epioestriol and other oestrogenic metabolites. 3. The sensitivity of the method is 1.3–1.6 μg/24 hours. 4. The quantitative and qualitative determination of urinary oestrogens with the above mentioned method was performed in 50 pregnant and 9 non pregnant women, and also in 2 patients with granulosa cell tumour.

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