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PubMed1985

[Effect of galactosidase enzymes on the glycoproteins of the platelet membrane determined using lectins].

Eight lectins specific for different 125I-labelled carbohydrates were employed to study the effect of the neuraminidase, alpha-galactosidase, and beta-galactosidase enzymes on the glycoproteins and terminal carbohydrates of platelet membranes. Neuraminidase was seen to cause a decrease in molecular weight, as measured by polyacrylamide gradient electrophoresis, in glycoproteins IIb and III; this was apparently due to an almost 50% decrease in N-acetyl-D-glucosamine terminals. At the same time, new D-mannose and D-galactose terminals became accessible to the lectins. The alpha- and beta-galactosidases did not seem to affect the molecular weight of the glycoproteins appreciably, though the N-acetyl-D-glucosamine terminals decreased and D-galactose debris increased; differences were observed in the effects of both enzymes. The results confirm that N-acetyl-D-glucosamine, D-mannose and D-galactose are the most abundant membrane carbohydrates and suggest that the first is found as a terminal whereas the others must also be located in the internal zones of the glycoproteins.

Blood Platelets↗
PubMed1977

Pseudo-clinical Fabry's disease without alpha galactosidase deficiency.

The authors describe two cases of clinical Fabry's disease. The first patient presents a deficiency of alpha galactosidase and a urinary excretion of ceramide trihexosides and dihexosides ; the second patient had a normal alpha galactosidase and normal excretion of urinary lipids. In this latter case the Km and the activity of the enzyme measured at different pH were similar to those of normal enzyme. The other lysosomal enzymes, beta galactosidase, beta glucosidase, hexosaminidases A and B, alpha fucosidase, arylsulfatases, phosphatase acids were also measured in patient 2 and all have normal activities. There is no urinary excretion of glycolipids or mucopolysaccharides. Yet this patient has an accumulation of material in his fibroblasts and renal cells. The authors also present a genetic study.

Adult↗
PubMed1977

DNA-directed in vitro synthesis of beta-galactosidase. Studies with purified factors.

The phage DNA-directed synthesis of beta-galactosidase has been examined in a system containing the following purified Escherichia coli factors: RNA polymerase; cyclic AMP receptor protein; N10-formyltetrahydrofolate Met-tRNAf transformylase; initiation factors 1, 2, and 3; elongation factors Tu, Ts, and G; release factors 1 and 2; 20 aminoacyl-tRNA synthetases; L factor (Kung, H. F., Spears, C., and Weissbach, H. (1974) J. Biol. Chem. 250, 1556-1562); and Lalpha (Kung, H.-F., Spears, C., and Weissbach, H. (1976) Fed. proc. 35, 1537). Under these conditions, beta-galactosidase synthesis occurs at less than 1% of the rate obtained with unfractionated extracts, which suggested that other required components were lacking. The difficulty in obtaining large amounts of the purified aminoacyl-tRNA synthetases for these studies made it necessary to modify the system. It was possible to conserve many of the purified aminoacyl-tRNA synthetases since at least 13 of them could be replaced by an Ehrlich ascites extract. The ascites extract plus other E. coli purified factors was used as a basic system to search for additional components required for beta-galactosidase synthesis. The present report describes the purification from E. coli extracts of three fractions, called Lbeta, Lgamma, and Ldelta, that are needed to restore enzyme synthesis.

Amino Acyl-tRNA Synthetases↗
PubMed1984

[Alpha-galactosidases and alpha-N-acetylgalactosaminidase. Biochemical bases of Fabry's disease].

The first part of this review deals with the new biochemical and genetical data concerning alpha-galactosidase and alpha-N-acetylgalactosaminidase. Molecular forms of these both enzymes can be classified into two groups following their physical, enzymatic and genetical properties: - the 3 forms of the alpha-galactosidase A group differ by the number of sialyl residues and their isoelectric point. All the forms of this group are heat-labile, hydrolyse only alpha-galactosides and proceed from the same alpha-GalA, X-linked gene. - alpha-galactosidase B is an alpha-N-acetylgalactosaminidase with broad substrate specificity, in vitro, is heat-stable and proceed from the alpha- GalB or alpha- NAGA gene of the chromosome 22. Structural and enzymatic data concerning these enzymes and their functions in the catabolism of glycosphingolipids and glycoproteins are reviewed. The second part deals with the pathophysiology of Fabry disease. The more prominent genetical and biochemical data and their diagnostic uses are reported: isozymic determination, cell cloning, quantitative determination of accumulated glycolipids. At last, were pointed the new developments of the research on Fabry disease: cultured cells as experimental model (fibroblasts, lymphoid cell lines) and therapeutic attempts.

Chemical Phenomena↗
PubMed1976

Inducing effect of cortisone and insulin on the activity of beta-galactosidase in the E. coli strains K12.

Individual and combined effects of cortisone and insulin on the synthesis of beta-galactosidase in the strains E. coli K 12 200 PS/Flac and M-308 and the possiblity of cortisone uptake by the bacterial cell under different temperature conditions were investigated in their dynamics. When insulin and cortisone are applied simultaneously in doses showing individually the greatest stimulative effect on the synthesis of beat-galactosidase, no summation of the effect of the hormones occurs in the strain E. coli 200 PS/Flac in the presence of IPTG while in the strain E. coli ML-308 simultaneous application of insulin and cortisone induces a negligible increase in the activity of beta-galactosidase. Tests for the incorporation of [3H] cortisone into the strains E. coli 200 PS/Flac and ML-308 have shown that the hormone is taken up by the bacterial cell immediately after its addition to the incubation medium, reaching its maximum after 5 min of incubation and maintaining the same level in the subsequent 30 min. The incorporation of [3H] cortisone at a temperature of 37degrees C is markedly higher than at 4degrees C. Preliminary incubation of the cultures with unlabelled cortisone and insulin resulted in a decrease in the uptake of [3H] cortisone by the bacterial cell.

Cortisone↗
PubMed1994

Immobilization of beta-galactosidase on metal-chelate-substituted gels.

The use of copper, zinc, iron, nickel and calcium in three different chelating gels was investigated for preparing immobilized beta-galactosidase. The chelated ligands [Cu(2+)-iminodiacetate (IDA), Cu(2+)-Tris(carboxymethyl)ethylenediamine (TED), Ni(2+)-IDA and Fe(3+)-IDA] absorbed the protein so strongly that it can be considered a true immobilization. The obtained enzyme derivatives were investigated with regard to activity and stability. Enzymic activity was highly preserved in general for the TED derivates (90% when compared with that for Cu(2+)-TED). The immobilized Ni2+ derivatives were more stable to high temperature and to storage than the Cu2+ derivatives. Temperature-stability of the immobilized enzyme was very much improved by adding a strong metal-chelating gel such as carboxymethylated tetraethylenepentamine-agarose. The gel could be re-used and reloaded after elution with chelator. beta-Galactosidase from Escherichia coli was purified using immobilized-metal-ion-chelate chromatography (i.m.a.c.). The potential use of beta-galactosidase immobilized on i.m.a.c. gels for technical purposes is discussed.

Chelating Agents↗
PubMed1995

Histochemical demonstration of different types of poly-N-acetyllactosamine structures in human thyroid neoplasms using lectins and endo-beta-galactosidase digestion.

Blood-group-related antigens expressed in papillary carcinomas and other types of neoplasm of the human thyroid glands have been shown to be carried by poly-N-acetyllactosamines containing a linear domain susceptible to endo-beta-galactosidase digestion. To make clear more precisely the backbone poly-N-acetyllactosamine structures, labelled lectins specific to different types of these structures and specific to core structures with beta 1-6GlcNAc branching of N- and O-linked glycoproteins were employed in conjunction with prior endo-beta-galactosidase digestion on formalin-fixed, paraffin-embedded neoplasms of the human thyroid glands. In papillary carcinomas, Datura stramonium agglutinin (DSA) and succinyl wheat germ agglutinin (Suc-WGA) reacted most consistently and frequently with papillary carcinomas from all the individuals examined. Pokeweed mitogen (PWM) likewise stained the cells of papillary carcinomas from all the individuals examined, but in some individuals the number of lectin-reactive cells were very small. Lycoperscion esculentum aggultinin (LEA), Solanum tuberosum agglutinin (STA), Phaseolus vulgaris agglutinin L (PHA-L) and Artocarpus integrifolia agglutinin (jacalin) similarly bound to the cancer cells from most of the individuals, and in these cases the number of reactive cells was usually much more restricted than was the case with DSA or PWM. In adenoma and other types of carcinoma, such as follicular carcinomas, these lectins specific to poly-N-acetyllactosamine exhibited slight or no reactivity with the cells, whereas PHA-L and jacalin similarly bound to the cells of adenomas and carcinomas from most of the individuals examined. Prior digestion with endo-beta-galactosidase completely eliminated or markedly reduced the reactivity with PWM and LEA in papillary carcinomas. Reactivity with DSA, Suc-WGA, STA, PHA-L and jacalin was slightly reduced or not at all affected by enzyme digestion. These results confirmed that poly-N-acetyllactosamine species found in papillary carcinomas are quite different from those in other types of thyroid neoplasm, suggesting that at least three different types of poly-N-acetyllactosamine, that is, linear unbranched short and long sequences and highly branched ones are produced in these cells.

Adult↗
PubMed1995

The biological activity of human monoclonal IgG anti-D is reduced by beta-galactosidase treatment.

The contribution to IgG effector function of exposed galactose residues on the oligosaccharide chains in IgG has been tested experimentally. We studied a human monoclonal antibody (BRAD-5) to the Rh D blood group antigen. The preparation used contained a very low percentage of agalactosyl IgG (3.6%). After digestion with beta-galactosidase there was an increase in terminal GlcNAc indicating an increase in % agalactosyl IgG to approximately 30%. Comparison was made of the Fc receptor-(Fc gamma R)-mediated functional interactions of the two glycoforms of BRAD-5 in assays which measured the recognition and destruction of sensitised erythrocytes by various effector cells. After beta-galactosidase treatment, there was a slight reduction in Fc gamma RI-mediated adherence of erythrocytes to U937 cells and phagocytosis of erythrocytes by monocytes. Fc gamma RII-mediated binding of erythrocytes to K562 cells was also reduced. However there was little difference in adherence of erythrocytes to either Daudi cells (via Fc gamma RII) or NK cells (via Fc gamma RIII). There was a consistent reduction in lysis of erythrocytes mediated through Fc gamma RIII on K cells with the beta-galactosidase treated anti-D. Overall the results showed that reduced levels of galactose on IgG anti-D were associated with reduced biological activity in these assays, but the experiments failed to cast light on the physiological role of the agalactosyl glycoform of IgG.

Antibodies, Monoclonal↗
PubMed1995

Isolation of a recombinant intracellular beta-galactosidase by ammonium sulfate fractionation of cell homogenates.

The Escherichia coli beta-galactosidase (EC 3.2.1.23) expressed intracellularly as soluble, biologically active enzyme in the yeast Saccharomyces cerevisiae was recovered from clarified homogenates of the yeast cells by precipitation with crystalline ammonium sulfate. Effects of salt saturation (0-80%) of the homogenate, the initial total protein level (2-20 g.L-1) and the processing pH (6-8) on the enzyme and protein recovery were investigated. As the ammonium sulfate concentration increased, the enzyme was precipitated preferentially and at 30% salt saturation nearly all had been recovered in the precipitate. In contrast, at this salt concentration only 25% of the total protein had precipitated. Preferential precipitation of beta-galactosidase was associated with the hydrophobic nature of this large protein. Complete precipitation of the total protein required salt concentrations exceeding 70% of saturation. The salt concentration needed for complete recovery of the enzyme was not sensitive to the processing pH. Over the salt saturation level of 20-50%, the enzyme precipitation followed the Cohn equation. The salting-out constant was strongly affected by the initial protein level in the homogenate; higher values were observed at lower protein concentrations. The salting-out constant was unaffected by the processing pH; however, the Cohn parameter B was pH dependent in addition to being affected by the initial protein concentration. Within the beta-galactosidase stability range of pH 6-8, pH variations alone (no added salt) proved ineffective in precipitating the enzyme.

Ammonium Sulfate↗
PubMed1997

Estimation and comparison of the contents of blood group B antigens in selected human tissues by microphotometric quantification of Griffonia simplicifolia agglutinin I-B4 staining with or without prior alpha-galactosidase digestion.

Griffonia simplicifolia agglutinin I-B4 (GSAI-B4) has broader specificity for B antigen variants and can recognize the antigens in a wide variety of human tissues. Thus, the concentration range of GSAI-B4 required for staining and the susceptibility of staining to alpha-galactosidase digestion is presumed to correlate well with the density of B antigens in tissue sections. By microphotometric quantification of staining intensity at different concentrations of GSAI-B4 with or without alpha-galactosidase digestion, concentration of B antigens in selected tissues was evaluated and compared. Based on the present results and the previous ones of direct measurement of galactose of B antigens in sublingual glands and red blood cells (Ito et al., 1993), the order of concentration of B antigens in tissues examined was estimated as follows; mucous cells of sublingual glands from German nonsecretors < red blood cells and vascular endothelial cells (= 2.7 x 10(-3) nmole/cm2), thyroid papillary carcinomas and Hassall's corpuscles from nonsecretors < mucous cells of sublingual gland from Japanese nonsecretors < pancreatic acinar cells from both secretor and nonsecretors, Hassall's corpuscles and kidney collecting tubules form secretors < mucous cells of sublingual gland from secretors (> 8.5-11.7 nmole/cm2) and mucous cells of Brunner's gland from nonsecretors < mucous cells of Brunner's gland from secretors. From the above estimation, it is apparent that the expression of B antigen in Brunner's gland is partly dependent on the secretor status of individuals and that Japanese nonsecretors secrete substantial amounts of B antigens from sublingual gland while German nonsecretors do not. The present results also revealed an unexpected staining behavior of GSAI-B4 in some tissues, i.e. in mucous cells of sublingual glands and collecting tubules of kidney from secretors, staining intensity was markedly depressed at higher concentration of the lectin and this depression was recovered by prior alpha-galactosidase digestion. In addition, the present method was successfully applied for the estimation of the content of B antigens neo-expressed in thyroid papillary carcinomas, showing that the content of B antigen had a similar level to that of red blood cells and vascular endothelial cells.

Antigens↗
PubMedDate not supplied

Study of Cryptococcus neoformans actin gene regulation with a beta-galactosidase-actin fusion.

An expression plasmid carrying a heterologous gene fusion between the Cryptococcus neoformans actin promoter and the Escherichia coli reporter gene, LACZ, was constructed to study actin regulation in C. neoformans. Two randomly stable transformants, designated 20.6 and 20.9, were selected for further examination. Both ectopic and homologous recombination with vector insertion in tandem repeats occurred in these transformants. Transformant 20.9 carried more copies of ACTp::LACZ in its genome than 20.6 and this was reflected in expressing higher levels of beta-galactosidase activity. In vitro, these transformants showed higher levels of beta-galactosidase activity expressed when the transformants were propagated at higher temperatures (37 degrees C vs 30 degrees C). However, beta-galactosidase expression in the transformants was variable during logarithmic and stationary growth phases and this differential expression was temperature dependent. This report shows that the constitutive actin gene in C. neoformans is regulated by temperature and growth and this fact should be taken into consideration when actin expression is used as a standard to compare the expression of other regulated genes. Also, a more sensitive reporter construct will be needed for in vivo gene analysis of regulation.

Actins↗
PubMed1998

alpha-Galactosidases of Penicillium simplicissimum: production, purification and characterization of the gene encoding AGLI.

Production of extracellular a-galactosidases by the filamentous fungus Penicillium simplicissimum (previously P. janthinellum) VTT-D-78090 was studied on different carbon sources. Steam-exploded oat husks were chosen as the best carbon source for enzyme production. Three a-galactosidases (AGL) were purified from the culture filtrate using ion-exchange chromatography, hydrophobic interaction chromatography and gel filtration. The isoelectric points of AGLI, AGLII and AGLIII were 5.2, 4.4 and 7.0, and the molecular masses as determined by SDS/PAGE were 61, 84 and 61 kDa, respectively. All enzymes were glycosylated. The optimum pH for the activity of AGLI and AGLIII was between 3.0 and 4.5 and that of AGLII was between 4.0 and 5.0. AGLII was more stable and more resistant to product inhibition by galactose than the other two enzymes. AGLI and AGLIII were also inhibited by p-nitrophenol-a-D-galactopyranoside, the substrate used for enzyme activity assay. The gene encoding AGLI was cloned and sequenced. The gene, agl1, encodes 435 amino acids including the signal sequence. It showed similarity with the other a-galactosidases belonging to the glycosyl hydrolase family 27. The N-terminal amino acid sequence of AGLIII was also similar to the sequences of other members of family 27, whereas the N-terminus of AGLII was completely different from the sequences of other reported hydrolases.

Amino Acid Sequence↗
PubMed1998

Alpha-galactosidase of the marine bacterium Pseudoalteromonas sp. KMM 701.

An alpha-galactosidase that inactivates the group specificity of B erythrocytes (group III) of human blood and does not affect A erythrocytes (group II) was isolated from the marine bacterium Pseudoalteromonas sp. KMM 701. The enzyme preparation did not contain lectin, hemolytic, sialidase, endoglycanase, or glycosidase activities. The enzyme is stable at 20 degreesC for 24 h, has pH optimum for catalysis within the range of 6.7-7.7, and is stable to high concentrations of NaCl. It is 4-fold more efficient than the alpha-galactosidase from green coffee beans. At pH 7.0 the Km for p-nitrophenyl-alpha-D-galactopyranoside is 0.29 mM. The molecular weight of the enzyme determined by gel-filtration is 195 +/- 5 kD. The alpha-galactosidase is denatured by urea and guanidine hydrochloride. Its activity does not depend on the presence of metal ions. It contains a sulfhydryl group essential for its catalytic activity.

ABO Blood-Group System↗
PubMed1986

Pathogenesis of shigella diarrhea: evidence for an N-linked glycoprotein shigella toxin receptor and receptor modulation by beta-galactosidase.

Pathogenic mechanisms in infectious diseases often involve specific receptor-ligand interactions of cells and soluble molecules. To further elucidate structure-function relations for shigella toxin receptors, we studied binding of purified 125I-labeled toxin and biologic response under various conditions in an experimental model using HeLa cells. Response to toxin was reversibly inhibited by treatment of cells with trypsin or tunicamycin, an inhibitor of glycoprotein synthesis that also significantly inhibited toxin binding, a result indicating that the receptor is an N-linked glycoprotein. Removal of terminal beta-linked galactose from the HeLa cell surface with beta-galactosidase increased toxin binding and activity, and it also potentiated the effects of lysozyme and wheat-germ agglutinin, which recognize oligomeric beta 1----4-linked N-acetyl-D-glucosamine and inhibit toxin activity as well. Incubation of cells with beta-N-acetylglucosaminidase, which cleaves terminal beta-linked N-acetyl-D-glucosamine, inhibited toxin activity. Effects of beta-galactosidase were reversed by readdition of galactose to cell-surface oligosaccharide acceptors. The data demonstrate that alterations of a single sugar on cell-surface glycoproteins may have a dramatic effect on receptor activity and indicate that shigella toxin is a sugar-binding protein with specificity for beta 1----4-linked N-acetyl-D-glucosamine.

Acetylglucosamine↗
PubMed1990

Partial apolipoprotein E-beta-galactosidase fusion protein expressed in Escherichia coli retains binding activity to the LDL(B/E) receptor.

A partial rat apo E-beta-galactosidase fusion protein was produced in Escherichia coli Y1089 infected with recombinant lambda GT11 obtained by immunoscreening of a rat liver cDNA library with an anti-rat LDL antiserum. Partial cDNA overlapped the apo E mRNA sequence coding for apo E binding domain towards the LDL(B/E) receptor up to codon for Arg-139. Fusion protein specifically bound to human fibroblasts. The high-affinity component exhibited a Kd of 5 x 10(-8) M and 4.1 x 10(5) sites per cell. Fusion protein binding to fibroblasts was mediated by their apo E moiety and not by beta-galactosidase since: (1) specific binding of fusion protein was competed out by human LDL; (2) beta-galactosidase did not compete with fusion protein binding; and (3) human fibroblasts from a patient with familial hypercholesterolemia, deficient in LDL(B/E) receptor, bound fusion protein 10-times lower than control fibroblasts. It was demonstrated that partial fusion protein retained the functional activity of the native apo E. However, compared to full-length native or engineered apo E, fusion protein was able to bind fibroblasts without being complexed with phospholipids. Fusion proteins might be a useful tool for studying the functional efficiency of the LDL(B/E) receptor and for mapping residues and domains involved in the binding process.

Apolipoproteins E↗
PubMed2004

Enzymatic synthesis of poly-N-acetyllactosamines as potential substrates for endo-beta-galactosidase-catalyzed hydrolytic and transglycosylation reactions.

Enzymatic synthesis of GlcNAc-terminated poly-N-acetyllactosamine beta-glycosides GlcNAcbeta1,3(Galbeta1,4GlcNAcbeta1,3)(n)Galbeta1,4GlcNAcbeta-pNP (n=1-4) was demonstrated using a transglycosylation reaction of Escherichia freundii endo-beta-galactosidase. The enzyme catalyzed a transglycosylation reaction on GlcNAcbeta1,3Galbeta1,4GlcNAcbeta-pNP (1), which served both as a donor and an acceptor, and converted 1 into p-nitrophenyl beta-glycosides GlcNAcbeta1,3(Galbeta1,4GlcNAcbeta1,3)(1)Galbeta1,4GlcNAcbeta-pNP (2), GlcNAcbeta1,3(Galbeta1,4GlcNAcbeta1,3)(2)Galbeta1,4GlcNAcbeta-pNP (3), GlcNAcbeta1,3(Galbeta1,4GlcNAcbeta1,3)(3)Galbeta1,4GlcNAcbeta-pNP (4) and GlcNAcbeta1,3(Galbeta1,4GlcNAcbeta1,3)(4)Galbeta1,4GlcNAcbeta-pNP (5). When 2 was used as an initial substrate, it led to the preferential synthesis of nonasaccharide beta-glycoside 4 to heptasaccharide beta-glycoside 3. This suggests that 4 is directly synthesized by transferring the tetrasaccharide unit GlcNAcbeta1,3Galbeta1,4GlcNAcbeta1,3Gal to nonreducing end GlcNAc residue of 2 itself. The efficiency of production of poly-N-acetyllactosamines by E. freundii endo-beta-galactosidase was significantly enhanced by the addition of BSA and by a low-temperature condition. Resulting 2 and 3 were shown to be useful for studying endo-beta-galactosidase-catalyzed hydrolytic and transglycosylation reactions.

Animals↗
PubMed2001

Purification and some characteristics of a recombinant dimeric rhizobium meliloti beta-galactosidase expressed in escherichia coli.

A recombinant Rhizobium meliloti beta-galactosidase was purified to homogeneity from an Escherichia coli expression system. The gene for the enzyme was cloned into a pKK223-3 plasmid which was then used to transform E. coli JM109 cells. The enzyme was purified 35-fold with a yield of 34% by a combination of DEAE-cellulose (pH 8.0) and two sequential Mono Q steps (at pH 8.0 and 6.0, respectively). The purified enzyme had an apparent molecular mass of 174 kDa and a subunit molecular weight of 88 kDa, indicating that it is a dimer. It was active with both synthetic substrates p-nitrophenyl beta-D-galactopyranoside (PNPG) and o-nitrophenyl beta-D-galactopyranoside (ONPG) with K(m)(PNPG) and K(m)(ONPG) of 1 mM at 25 degrees C. The k(cat)/K(m) ratios for both substrates were approximately 70 mM(-1) sec(-1), indicating no clear preference for either PNPG or ONPG, unlike E. coli beta-galactosidase. After non-denaturing electrophoresis, active beta-galactosidase bands were identified using 5-bromo-4-chloro-3-indolyl beta-D-galactopyranoside (X-gal) or 6-bromo-2-naphthyl beta-D-galactopyranoside (BNG) and diazo blue B.

Journal Article↗
PubMed1998

Effect of chlorination on beta-D-galactosidase activity of sewage bacteria and Escherichia coli.

The effect of chlorine on beta-D-galactosidase activity of sewage bacteria and Escherichia coli was studied. beta-D-galactosidase activity of sewage was more resistant to chlorine than faecal coliform cultivability. At low initial dosage (0.05 mg Cl2 l-1) neither cultivability (colony-forming units (cfu)), nor enzyme activity of E. coli suspensions were severely impaired. When initial chlorine concentration was increased to 0.1 mg Cl2 l-1, the cfu number decreased whereas enzyme activity remained high, i.e. the enzyme activity calculated cfu-1 increased. At higher chlorine doses both cfu and enzyme activity were reduced, but non-cultivable cells retained assayable activity after chlorination. Mean values of the enzyme activity calculated cfu-1 decreased when the chlorine dosage was increased from 0.1 to 0.5 mg Cl2 l-1, but were not significantly different (P > 0.05) for dosages of 0.2-0.7 mg Cl2 l-1. After chlorination, beta-D-galactosidase activity of E. coli was less reduced than cfu and direct viable count numbers, but more reduced than 5-cyano-2-3, ditolyl tetrazolium chloride and total cell counts, and the enzyme activity represented an alternative activity parameter of chlorinated samples.

Bacterial Proteins↗