Purification of beta-glucosidase activities from bovine spleen by affinity chromatography

Activities of hydrolases and oxidases as influenced by the application of monocrotophos in sandy loam soil of Rajasthan

Continuous and repeated use of pesticides affects soil microbial flora and fauna and hence indirectly affects the activity of diverse microbial enzymes present within it. The present study investigates the interaction effect of different concentrations of monocrotophos on diverse hydrolases and oxidases, viz., protease, alkaline phosphatase, acid phosphatase, cellulase, amylase, invertase, arginine deaminase, and dehydrogenase, present in sandy loam soil of Rajasthan under in vitro conditions for 30 days. Soil sample was inoculated with three different concentrations of monocrotophos, viz., 50, 100, and 150 μg kg(-1), and incubated in dark at room temperature. At regular interval of 5 days, sample was withdrawn and enzyme activity was calculated and compared with that of control. Application of various concentrations of monocrotophos enhanced the activity of diverse enzymes present in soil. Therefore, the study revealed synergistic or additive effect of monocrotophos on all the tested microbial enzyme entities. Increasing concentration of the pesticide, however, poses an antagonistic interaction on the increment of different enzymes activities. Therefore, it can be concluded from the study that monocrotophos impose a positive effect at low concentration of pesticide, whereas high concentration poses negative effect on the activity of different enzymes present in soil.

Structural analysis of the human glucocerebrosidase genes

Two different genomic clones containing the entire coding sequence of human glucocerebrosidase were isolated from a fetal liver library using a cDNA probe previously cloned by us. These clones correspond to two human glucocerebrosidase genes, designated 6-1 and 10-2. Clone 6-1 contains sequences homologous to the cDNA we cloned previously. The promoter regions of the genes were identified by S1 analysis and sequenced. They contain TATA- and CAAT-like boxes, but lack a GGCGGG motif. When coupled to the bacterial gene coding for chloramphenicol acetyl transferase (CAT) and transfected to Gaucher skin fibroblast lines, both promoter fragments enhanced CAT activity. The promoter of gene 6-1 was eight times more efficient than the promoter of gene 10-2. Northern blot analysis revealed three human glucocerebrosidase RNA species of 6, 2.6, and 2.2 kb in size. The 6-kb transcript is probably a nuclear transcript whereas the 2.6-kb and 2.2-kb transcripts are cytoplasmic species which emerge from polyadenylation at different sites.

Human lysosomal beta-glucosidase: purification by affinity chromatography

Two Sepharose-bound substrate analogs, 6'-aminohexanoyl-(2-N-sphingosyl-O-beta-D-glucoside) and 6'-aminohexyl-dodecanedioyl-1-(2-N-sphingosyl-1-O-beta-D-glu coside), were synthesized and used sequentially for the affinity purification of lysosomal beta-glucosidase (N-acyl-sphingosyl-1-O-beta-D-glucoside:glucohydrolase, EC 3.2.1.45). The capacities of these nondegradable affinity supports were 0.1 and 0.15 mg enzyme/ml settled gel, respectively. The purified enzyme had a specific activity of 75 mumol min-1 mg-1. The preparation had a single protein band with a molecular weight of 67,000 on sodium dodecyl sulfate-polyacrylamide gel electrophoresis, evidencing its apparent homogeneity. Isoelectric focusing on granular gels revealed four molecular forms of the enzyme with pI values of 4.0, 4.5, 4.7, and 5.8 to 6.2. The purified enzyme hydrolyzed glucosyl ceramide and 4-methylumbelliferyl-beta-D-glucoside with Km and Vmax values of 0.6 and 2.5 mM, and 101 and 26.1 mumol min-1 mg-1, respectively. The enzyme also hydrolyzed octyl beta-glucoside, a linear mixed-type inhibitor of the enzyme. Binding constants (Ki) were determined for the inhibitors, sphingosyl-1-O-beta-D-glucoside (Ki = 20 microM) and its N-hexyl derivative (Ki = 0.3 microM). The enzyme had a half-life of 65 and 30 min at 50 degrees C and pH 5.0 or 6.0, respectively. In addition, two other classes of ligands were used for the purification of lysosomal beta-glucosidase, and their capacities and specificities were compared to those of the substrate analog affinity supports. These included (i) the alkyl amine inhibitors octylamine, decylamine, and tetradecylamine; and (ii) the inhibitors, 6-aminohexanoyl-beta-glucosylamine and aminododecanoyl-1-(2-N-sphingosyl-1-O-beta-D-glucoside). Compared to these other ligand columns, the substrate analog affinity supports had about 100- to 1000-fold greater capacities or afforded 8- to 40-fold greater purification of human lysosomal beta-glucosidase.

Synthesis of a fluorescent derivative of glucosyl ceramide for the sensitive determination of glucocerebrosidase activity

A fluorescent derivative of glucosyl ceramide was synthesized by covalently linking a fluorescent fatty acid, 12-[N-methyl-N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)] aminododecanoic acid to the amino group of sphingosyl-1-O-beta-D-glucoside, glucosyl sphingosine. For hydrolysis by glucocerebrosidase, this substrate was dispersed in mixed micelles with Triton X-100 and sodium taurocholate or in unilamellar liposomes with phosphatidylcholine and the negatively charged lipid, dicetylphosphate. In either micellar or liposomal dispersions of the fluorescent substrate, reaction rates were linear with time and protein concentration, and saturation kinetics were observed. The rate of hydrolysis of this fluorescent substrate was equal to that obtained with radiolabeled glucosyl ceramide. The fluorescent glucosyl ceramide was used to determine glucocerebrosidase activity in extracts of human leukocytes, cultured skin fibroblasts, and various tissues as well as in partially purified splenic and placental glucocerebrosidase preparations. This fluorescent derivative of the natural substrate was not hydrolyzed by aryl beta-glucosidase(s), thereby facilitating the specific and reliable diagnosis of heterozygotes and homozygotes with Gaucher disease.

Immunohistochemical localization of β-glucosidases in lignin and isoflavone metabolism in Cicer arietinum L. seedlings

Coniferin specific- and isoflavone 7-glucoside specific β-glucosidases have been localized in stem and root sections of chick pea (Cicer arietinum L.) seedlings by the indirect immunofluorometrical method. The coniferin specific β-glucosidase has been found in the cell walls of the tracheary elements and of the endo-, epi-, and exodermis. All these tissues are known to contain either lignin or polymers, like suberin and cutin, which consist partially of phenylpropanoid elements. The localization of this β-glucosidase is therefore in agreement with its postulated relationship to the phenylpropanoid metabolism. The isoflavone 7-glucoside specific β-glucosidase, on the other hand, is predominantly located in the parenchymatic cortex cells, and obviously in the cytoplasm. These cells are known to contain the isoflavone formononetin, which has been shown to undergo turnover in chick pea seedlings. We therefore have good reason to assume that this β-glucosidase is involved in the metabolism of the 7-glucoside of this isoflavone.

The turnover of hamster fibroblast lysosomal beta-D-glucuronidase

The half-life of hamster fibroblast beta-D-glucuronidase (EC 3.2.1.31) was estimated to be 4-5 days by measuring the decay with time of the radioactivity in beta-D-glucuronidase isolated from cells grown in the presence of 14C-labelled amino acids. A new affinity-chromatographic procedure for the purification of beta-D-glucuronidase is described.

Hydrolytic and transglucosylation activities of a purified calf spleen beta-glucosidase

Certain properties of the transglucosylitic activity and the hydrolytic activity of a purified calf spleen beta-glucosidase (beta-D-glucoside glucohydrolase EC 3.2.1.21) were investigated. There was a stimulation of both activities by sodium taurocholate and "Gaucher's factor". The K-m values for 4-methylumbelliferyl-beta-D-glucoside and glucosylceramide as donors in the transglucosylation reaction were 2 mM and 0.075 mM, respectively. The K-m for ceramide as acceptor was 0.149 mM with both of these compounds. The ability of several glucoside to act as donors was examined. The capacity to catalyze this "transglucosylation" reaction is greatly diminished in spleen tissue samples from Gaucher's patients. The enzyme possesses the capacity to hyrolyze 4-methylumbellifery-beta-D-glucoside, p-nitrophenyl-beta-D-glucoside, glucosylsphingosine, glucosylceramide and deoxycorticosterol-beta-D-glucoside. It is postulated that a single enzyme protein may be responsible for both the hydrolytic and the transglucosylitic activities.