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.

scholarly journals Elucidation of the topological parameters of N-acetylneuraminic acid and some analogues involved in their interaction with the N-acetylneuraminate lyase from Clostridium perfringens

1992 ◽  
Vol 282 (2) ◽  
pp. 511-516 ◽  
Author(s):  
E Zbiral ◽  
R G Kleineidam ◽  
E Schreiner ◽  
M Hartmann ◽  
R Christian ◽  
...  
Keyword(s):  
Sialic Acid ◽  
Oxygen Atom ◽  
Clostridium Perfringens ◽  
Pyruvic Acid ◽  
Sialic Acids ◽  
Side Chain ◽  
Equatorial Zone ◽  
Enzyme Action ◽  
Acetylneuraminic Acid ◽  
Topological Parameters

A series of neuraminic acid derivatives modified in the side chain or at C-3, C-4 or C-5 were tested as substrates of inhibitors of N-acetylneuraminate lyase (EC 4.1.3.3) from Clostridium perfringens. The results, together with Km and Ki values reported previously, indicate that the region most important for the binding of sialic acids is an equatorial zone reaching from C-8 via the ring oxygen atom to C-4 of the sugar molecule, whereas the substituents at C-9 and C-5 may be varied to a higher extent without significantly disturbing enzyme action. It is shown that stereo-electronic factors are responsible for the immediate heterolytic fragmentation of the cyclic sialic acid into pyruvic acid and 2-acetamidomannose or a related C-6 sugar.

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.

Multiresidue Method for Determination of Eight Neutral β-Lactam Penicillins in Milk by Fluorescence-Liquid Chromatography

1985 ◽  
Vol 68 (5) ◽  
pp. 968-971
Author(s):  
Robert K Munns ◽  
Wilbert Shimoda ◽  
Jose E Roybal ◽  
Cassandra Vieira
Keyword(s):  
Liquid Chromatography ◽  
Mobile Phase ◽  
Methylene Chloride ◽  
Side Chain ◽  
Excitation Wavelength ◽  
Benzyl Penicillin ◽  
Aqueous Fraction ◽  
Phenoxymethyl Penicillin ◽  
Hydrolysis Of

Abstract A method of determining total penicillins begins with an enzymatic hydrolysis of the (J-Iactam ring to form their respective penicilloate product. Acetonitrile precipitates much of the casein and protein, which are then separated from the liquid by centrifugation. The lipids are removed from the aqueous fraction with methylene chloride. Mercuric chloride is added, which reacts with the penicilloate to liberate the side chain that has a terminal aldehyde. These penilloaldehyde products are extracted with methylene chloride and are subsequently reacted with dansyl hydrazine. The resulting fluorolabeled side chains are separated by liquid chromatography on a C18 column with acetonitrile- water as mobile phase. The fluorescence is measured by the mercury line at 254 nm excitation wavelength and a 500 nm filter on the emission side. The overall average recoveries from milk spiked at 25, 50, and 100 ppb are benzyl penicillin 79.4%; phenoxymethyl penicillin 59.7%; phenethicillin 75.9%; nafcillin 87.7%; methacillin 47.5%; oxacillin 57.6%; cloxicillin 37.3%; and dicloxicillin 26.4%.

scholarly journals Kinetic mechanism of Clostridium perfringens phospholipase C. Hydrolysis of a thiophosphate analogue of lysophosphatidylcholine

1991 ◽  
Vol 280 (2) ◽  
pp. 407-410 ◽  
Author(s):  
P R Young ◽  
W R Snyder ◽  
R F McMahon
Keyword(s):  
Phospholipase C ◽  
Clostridium Perfringens ◽  
Kinetic Mechanism ◽  
Compound I ◽  
Nitrobenzoic Acid ◽  
Competitive Mechanism ◽  
Simple Slope ◽  
Continuous Assay ◽  
Hydrolysis Of

The hydrolysis of S-[2-(hexadecanoyloxy)ethyl]thiophosphocholine (I), an analogue of lysophosphatidylcholine, by Clostridium perfringens phospholipase C, was followed at pH 7.5, 37 degrees C and I 1.0 (maintained with KCl), in a continuous assay, by monitoring the reduction of 5,5′-dithiobis-(2-nitrobenzoic acid) at 412 nm. Simple saturation kinetics are observed with linear mixed-type slope-intercept effects for the hydrolysis of compound (I) with variable [Ca2+] at fixed concentrations of compound (I) and a simple slope effect as [compound (I)] is varied at fixed concentrations of Ca2+. These data are consistent with a simple ordered rapid-equilibrium mechanism in which Ca2+ binds to the enzyme first followed by substrate. The observed kinetic constants at pH 7.5, 37 degrees C and I 1.0 are K1 = 12.0 mM (Ca2+ dissociation), K2 = 36 microM [compound (I) dissociation] and Vmax. = 552 microM.min-1.mg-1. Alkane diammonium salts inhibit the enzyme by a non-competitive mechanism that involves binding to free enzyme, E.Ca2+ and E.Ca2+.S. The use of the simple micellarized substrate under these conditions allows the determination of kinetic and inhibition constants without complications arising from enzyme-micelle interactions.

scholarly journals Effect of modification of sialic acid on enzymic hydrolysis of gangliosides GM1 and GM2.

1984 ◽  
Vol 259 (9) ◽  
pp. 5409-5410
Author(s):  
S C Li ◽  
S Serizawa ◽  
Y T Li ◽  
K Nakamura ◽  
S Handa
Keyword(s):  
Sialic Acid ◽  
Enzymic Hydrolysis ◽  
Hydrolysis Of

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
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