Screening for carbohydrate-binding proteins in extracts of Uruguayan plants.

The presence of carbohydrate-binding proteins, namely lectins, -galactosidases and amylases, was determined in aqueous extracts of plants collected in Uruguay. Twenty-six extracts were prepared from 15 Uruguayan plants belonging to 12 Phanerogam families. Among them, 18 extracts caused hemagglutination (HAG) that was inhibited by mono- and disaccharides in 13 cases, indicating the presence of lectins. The other 8 extracts did not cause any HAG with the four systems used to detect HAG activity (rabbit and mouse red cells, trypsin-treated rabbit and mouse red cells). For the extracts prepared from Solanum commersonii, HAG activity and HAG inhibition were similar for those prepared from tubers, leaves and fruits, with the chitocompounds being responsible for all the inhibitions. Purification of the S. commersonii tuber lectin was carried out by affinity chromatography on asialofetuin-Sepharose, and SDS-PAGE under reducing conditions gave a single band of Mr of approximately 80 kDa. The monomer N-acetylglucosamine did not inhibit HAG induced by the purified lectin, but chitobiose inhibited HAG at 24 mM and chitotriose inhibited it at 1 mM. -Galactosidase activity was detected in leaves and stems of Cayaponia martiana, and in seeds from Datura ferox. Only traces of amylase activity were detected in some of the extracts analyzed. The present screening increases knowledge about the occurrence of carbohydrate-binding proteins present in regional plants.

Screening for carbohydrate-binding proteins in extracts of Uruguayan plants

The presence of carbohydrate-binding proteins, namely lectins, ß-galactosidases and amylases, was determined in aqueous extracts of plants collected in Uruguay. Twenty-six extracts were prepared from 15 Uruguayan plants belonging to 12 Phanerogam families. Among them, 18 extracts caused hemagglutination (HAG) that was inhibited by mono- and disaccharides in 13 cases, indicating the presence of lectins. The other 8 extracts did not cause any HAG with the four systems used to detect HAG activity (rabbit and mouse red cells, trypsin-treated rabbit and mouse red cells). For the extracts prepared from Solanum commersonii, HAG activity and HAG inhibition were similar for those prepared from tubers, leaves and fruits, with the chitocompounds being responsible for all the inhibitions. Purification of the S. commersonii tuber lectin was carried out by affinity chromatography on asialofetuin-Sepharose, and SDS-PAGE under reducing conditions gave a single band of Mr of approximately 80 kDa. The monomer N-acetylglucosamine did not inhibit HAG induced by the purified lectin, but chitobiose inhibited HAG at 24 mM and chitotriose inhibited it at 1 mM. ß-Galactosidase activity was detected in leaves and stems of Cayaponia martiana, and in seeds from Datura ferox. Only traces of amylase activity were detected in some of the extracts analyzed. The present screening increases knowledge about the occurrence of carbohydrate-binding proteins present in regional plants

Isolation of a beta-galactoside-binding lectin from cat liver.

A lectin from cat liver has been identified and purified by affinity chromatography on asialofetuin-Sepharose. One hundred micrograms of lectin was obtained from one cat liver with a purification factor of 1561. The lectin agglutinates trypsin-treated rabbit and cow erythrocytes. Hemagglutination was inhibited only by saccharides containing -galactosyl residues, of which the 1-amine-1-deoxy- -D-galactose was the most potent one by inhibiting hemagglutination at a concentration of 12.5 mM, followed by melibiose, trehalose and galactose. The lectin has a subunit molecular mass of 14.4 kDa determined by SDS-PAGE under reducing conditions and a pI of 4.85. Compared with the composition of lectins from calf heart and porcine heart, cat liver lectin contains approximately the same amount of cysteine, half the amount of glycine, twice as much arginine and threonine, and three times the amounts of tyrosine and methionine. Cat liver lectin contains four cysteine residues per subunit, all of them in the reduced form. Their lack of reactivity towards thiol-reactive supports suggests they are not exposed on the lectin surface. The protein apparently has a blocked N-terminus. The purified lectin was stable for up to 20 months stored at +4 C in buffer supplemented with 4 mM -mercaptoethanol. Results indicated that this lectin belongs to the family of soluble -galactoside-binding lectins, also known as galectins, which are expressed in a wide range of vertebrate tissues.

Isolation of a á-galactoside-binding lectin from cat liver

A lectin from cat liver has been identified and purified by affinity chromatography on asialofetuin-Sepharose. One hundred micrograms of lectin was obtained from one cat liver with a purification factor of 1561. The lectin agglutinates trypsin-treated rabbit and cow erythrocytes. Hemagglutination was inhibited only by saccharides containing á-galactosyl residues, of which the 1-amine-1-deoxy-á-D-galactose was the most potent one by inhibiting hemagglutination at a concentration of 12.5 mM, followed by melibiose, trehalose and galactose. The lectin has a subunit molecular mass of 14.4 kDa determined by SDS-PAGE under reducing conditions and a pI of 4.85. Compared with the composition of lectins from calf heart and porcine heart, cat liver lectin contains approximately the same amount of cysteine, half the amount of glycine, twice as much arginine and threonine, and three times the amounts of tyrosine and methionine. Cat liver lectin contains four cysteine residues per subunit, all of them in the reduced form. Their lack of reactivity towards thiol-reactive supports suggests they are not exposed on the lectin surface. The protein apparently has a blocked N-terminus. The purified lectin was stable for up to 20 months stored at +4ºC in buffer supplemented with 4 mM á-mercaptoethanol. Results indicated that this lectin belongs to the family of soluble á-galactoside-binding lectins, also known as galectins, which are expressed in a wide range of vertebrate tissues

Production of capsular polysaccharide of Streptococcus pneumoniae type 14 and its purification by affinity chromatography.

We describe a rapid and efficient method for producing the capsular polysaccharide of Streptococcus pneumoniae by fermentation on tryptic soy broth and purification of this compound by using immobilized soybean lectin as an affinity adsorbent. In principle, the same strategy can be used to produce purified capsular polysaccharides from other streptococcal serotypes by selecting the appropriate lectin adsorbents.

Introduction of thiol-reactive structures on to soluble and insoluble proteins.

When proteins containing disulphide groups were oxidized with magnesium monoperoxyphthalate at acidic pH, they acquired the property of binding thiol compounds. This was the case with the insoluble protein keratin, chosen for having a large number of disulphide bridges, and with soluble ones like BSA and immunoglobulins. The potential applications of some of these modified proteins for the preparation of soluble bioconjugates have been explored. As a particular example of an application, the immobilization of activated IgG on to solid phases might provide a new way for preparing immunoadsorbents.

Chromatographic methods for amylases.

This review surveys recent developments in chromatographic methods for the separation of amylases from complex extracts, including the separation of isozymes. It contains two tables with the properties and molecular characteristics of alpha-and beta-amylases from different sources as well as an updated review of methods for the determination of amylase activity. The main subject of this review is a detailed evaluation of the application of newly developed chromatographic methods for the purification of amylases.

Selective adsorption of immunoglobulins and glucosylated proteins on phenylboronate-agarose.

Aminophenylboronate-substituted agarose in 20 mM N-2-hydroxyethylpiperazine-N'-2-ethanesulphonic acid, pH 8.5, selectively adsorbs immunoglobulins and complement factors C3 and C4 from human serum. The selectivity of binding is strongly influenced by the presence of magnesium chloride in the sample buffer. Adsorbed immunoglobulins are quantitatively eluted by sorbitol, but only partially by ethylene glycol or methylcellosolve. Aniline-agarose of a similar degree of substitution shows only weak adsorption of serum proteins under similar experimental conditions, thus indicating the important contribution of the boronate moiety to this interaction. Immunoglobulin adsorption seems not to be due to the cis-diol complexation used extensively for the chromatographic determination of non-enzymatically glucosylated proteins. Hydrophobic and pi-pi interactions with the aromatic structure of the ligand seem also to contribute to protein binding. The behaviour of aminophenylboronate-liganded agarose is, in some respects, rather similar to that of the so-called "thiophilic adsorbents".

Purification of uricase by biospecific adsorption-desorption.

A simple procedure for the purification of uricase from bovine kidney is described. The procedure involves the following steps: 1) processing of kidney mince by borate/butanol, 2) ammonium sulphate precipitation, and 3) biospecific adsorption-desorption. The adsorbents were prepared by chemical attachment of urate or xanthine to agarose gel beads. The desorption was performed by a xanthine solution. The adsorption-desorption procedure resulted in an 11 000-12 000-fold purification. The specific activity of the purified uricase was 19.8 U/mg using either "urate" adsorbent. The recovery was about 70%. The adsorbents were also used for the purification of commercial uricase preparations from hog liver. In this case the purified uricase also possessed a specific activity of 19.8 U/mg. The products were homogenous as judged by gradipore electrophoresis and gel filtration.