Thin-layer chromatographic demonstration of aspartylglycosylamine and a novel acidic carbohydrate in human tissues

Purification and properties of an endo-1,4-xylanase excreted by a hydrolytic thermophilic anaerobe, Clostridium thermolacticum. A proposal for its action mechanism on larchwood 4-O-methylglucuronoxylan

An extracellular xylanase from a thermophilic anaerobe, Clostridium thermolacticum, was purified 400-fold by ion-exchange chromatography and gel filtration. The purified enzyme had a specific activity of 31,670 nkat/mg of protein at 60 degrees C, a molecular mass of 39 kDa and a pI of 4.9. The enzyme exhibited maximal activity at 80 degrees C (1 h assay) and at pH 6.0-6.5. There was little loss of activity after 4 days at 60 degrees C and the enzyme was stable in the wide pH range 3-11. Examination of the hydrolysis products of larchwood xylan indicated that it was an endoxylanase; at the early stage of the reaction, xylose (Xyl)-containing oligosaccharides of 3-12 residues were released and after a prolonged incubation time, the neutral end-products were Xyl2 and Xyl3. Kinetic studies of the hydrolysis of xylose-containing oligosaccharides of 4-7 residues showed that the tetrasaccharide was hydrolysed more slowly than the pentasaccharide, while the calculated Km and V values for pentasaccharide and hexasaccharide were similar. The primary structures of the XylnGlcA produced by long-term hydrolysis of larchwood glucuronoxylan were determined on the basis of their carbohydrate composition, by methylation analysis and by 1H-NMR and 13C-NMR spectroscopies. These data allowed us to propose a model for the mode of action of this endoxylanase on larchwood 4-O-methylglucuronoxylan.

Analysis of aspartylglucosamine at the picomole level by high-performance liquid chromatography

A sensitive method for quantitative analysis of aspartylglucosamine as its dabsyl chloride derivative by high-performance liquid chromatography is described. Precolumn-derivatized aspartylglucosamine and internal standard (carboxymethylcysteine) are separated on a reversed-phase column with a mobile phase consisting of phosphate buffer and acetonitrile and monitored by UV-VIS detection at 436 nm. Aspartylglucosamine acts in the assay like a polar amino acid, and it can be separated from interfering substances in urine with a retention time of ca. 13 min. Its detection limit is ca. 0.3 microM in water and 0.5-1.0 microM in urine and other biological samples, which permits its quantitation in normal urine, for example. The within-day coefficient of variation is less than 4.7% and the day-to-day coefficient of variation is less than 8.3%. The present method is applicable to the direct analysis of aspartylglucosamine in body fluids and tissues without any prepurification and, in combination with automated liquid chromatography, allows rapid assay of a large number of samples in the detection of aspartylglycosaminuria. The sensitivity of the assay also allows direct quantitation of aspartylglucosamine in normal urine and leukocytes of aspartylglycosaminuria patients, and may thus be used in metabolic studies of the compound.

Abnormal membrane cation transport in pregnancy-induced hypertension

An abnormality of sodium handling has been suggested as one of the mechanisms responsible for the development of pregnancy-induced hypertension. We analysed the plasma and urinary concentrations, and the intraerythrocyte activities of Na and K, and the RBC membrane Na+/K+-ATPase activity of 77 hypertensive and 133 normal pregnant women. Umbilical cord blood of infants from 21 hypertensive and 28 control women was studied. The Na+/K+-ATPase activity was determined by measuring the inorganic phosphate released by incubation in a reaction medium in the presence and absence of K ions or ouabain. The intra-erythrocyte sodium and potassium activities were measured by ion-selective electrode analysis of the haemolysates, after washing the RBCs in 110 mmol/l MgCl2. We found a significant increase in intracellular sodium and a reduction in Na+/K+-ATPase activity in the hypertensive women in comparison with the control subjects during pregnancy. No difference was observed in early puerperium. Cord blood from infants of pregnancy-induced hypertensive women showed an increase in intracellular Na+ activity and a decrease in the erythrocyte membrane Na+/K+-ATPase activity in comparison with cord blood samples from control subjects. The observed abnormalities in the plasma membrane sodium transport may play a major role in the pathophysiology of pregnancy-induced hypertension.

Profiling of carbohydrates, glycoproteins and glycolipids

Current chromatographic methods for the analysis of a variety of carbohydrate materials in body fluids and tissues have been reviewed, from the viewpoints of clean-up of samples, separation modes, methods for detection and quantification, and degree of convenience. This review also contains several tables, listing names of samples, methods of analysis, analytical conditions, and normal as well as pathological levels reported, from representative publications.

Comparative study of the carbohydrate moieties of normal and pathological human immunoglobulins M

The well-known heterogeneity of normal and pathological immunoglobulins M was investigated in a study involving the characterization of their carbohydrate moieties. Oligosaccharide units were released from the native molecule by hydrazinolysis, and they were fractionated by affinity chromatography on a concanavalin A-Sepharose column to yield separate N-acetyl-lactosaminic-type and oligomannosidic-type structures. Further identification of these oligosaccharides was attempted by t.l.c. on silica gel and by determination of their monosaccharide compositions. A comparative study of the oligosaccharide units belonging to each population of immunoglobulin M was possible. Similarities were found in the occurrence of both types of oligosaccharide structures, and, in addition, a common double heterogeneity could be demonstrated for N-acetyl-lactosaminic-type structures: they could be resolved by affinity chromatography into bi-, tri- and tetra-antennary structures, and they also showed differences in N-acetylneuraminic acid content. Though some variations were observed in the exact composition of the oligosaccharide units within each population, it was possible to consider a representative oligosaccharide-unit composition of normal immunoglobulin M as a standard for comparison. On this basis a predominance of multi-antennary structures was observed in the more glycosylated pathological immunoglobulins M (10% carbohydrate content), whereas oligomannosidic structures were increased in pathological immunoglobulins M with a lower content of carbohydrates (7%). These variations are thought to reflect differences in the biosynthetic processing pathway of the carbohydrate units of the pathological immunoglobulins M or the enhanced expression of a molecular clone.

Aspartylglycosaminuria: an inborn error of glycoprotein catabolism

Aspartylglycosaminuria (AGU, McKusick 20840) is a metabolic disorder affecting the catabolism of glycoproteins. It was first described in 1967, by Jenner and Pollitt, in two mentally retarded English siblings. Subsequently several cases were reported from Finland (Palo and Mattsson, 1970; Autio, 1972; Autio et al., 1973). Today the number of known cases is about 140, most of them Finnish or of Finnish origin (Aula et al., 1980). The incidence of AGU in Finland has been estimated to be approximately 1:26000 and the disease is inherited as an autosomal recessive trait (Autio et al., 1973). Clinical manifestations include progressive mental retardation, coarse gargoyle-like facial features, skeletal abnormalities and recurrent infections. Early development of the patients is usually normal, but by the age of 5-15 years they are already severely retarded (Autio, 1972; Autio et al., 1973). Morphologically AGU is a generalized storage disease (Haltia et al., 1975). Affected tissues show enlarged lysosomes. Vacuolization is a prominent feature of liver and nerve cells (Haltia et al., 1975) and of peripheral lymphocytes (Aula et al., 1975).

Aspartylglucosaminuria: unique biochemical and ultrastructural characteristics

The observation of vacuolated lymphocytes in a coarsely featured two year old female with hepatosplenomegaly, mitral insufficiency, and mild psychomotor retardation led to the first diagnosed case of aspartylglucosaminuria in the United States. Although physical characteristics and bone roentgenograms were consistent with a mucopolysaccharide disorder, analysis of the urine showed no mucopolysaccharide elevation. The chromatographic, enzymatic, and ultrastructural studies confirming the diagnosis are presented.

Aspartylglucosaminuria: psychomotor retardation masquerading as a mucopolysaccharidosis

A 5-year-old girl with coarse facies, visceromegaly, and vacuolated lymphocytes is presented as the first case of aspartylglucosaminuria diagnosed in this country. This metabolic defect in glycoprotein catabolism can be clinically confused with other storage diseases such as the mucopolysaccharidoses and mucolipidoses. It is not diagnosed by routine laboratory screening methods. Special studies are required to confirm the diagnosis, but a thin-layer chromatography method for screening urine is presented for use when the diagnosis is suspected. The developmental potential in this inborn error of metabolism is documented.