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At least 19 recordsLinked to original sources
PubMed1975

Inhibition of human liver beta-galactosidases and beta-glucosidase by n-bromoacetyl-beta-D-galactosylamine.

N-Bromoacetyl-beta-D-galactosylamine is an irreversible inhibitor of the 'acid' and the 'neutral' beta-galactosidases (beta-D-galactoside galactohydrolase, EC 3.2.1.23) of human liver. The inactivation of acid beta-galactosidase appears to involve a group with a pKa = 4.5. The inhibition of neutral beta-galactosidase only occurs above pH 8.0. Both enzymes are protected against inhibition by the presence of substrates, suggesting that the inhibitor reacts with the active site of the enzymes. Other lysosomal hydrolases are not inhibited by N-bromoacetyl-beta-D-galactosylamine, with the exception of 'neutral' beta-glucosidase (beta-D-glucoside glucohydrolase, EC 3.2.1.21). The pH dependence of neutral beta-glucosidase inactivation is essentially identical to that of the neutral beta-galactosidase. Inhibition of beta-glucosidase by this galactose derivative suggests that the same enzyme may bind glucosides and galactosides. Furthermore, both neutral beta-galactosidase and beta-glucosidase are inactivated at 52 degrees C with a half-life of 7.5 min. The presence of a single enzyme with both beta-glucosidase and beta-galactosidase activities is also supported by mixed-substrate experiments.

Acetylgalactosamine↗
PubMed1975

Stimulation of rat liver beta-galactosidase activity by ions.

1. The p-nitrophenyl beta-D-galactosidase asctivity in rat liver homogenates of lysosome-rich fractions was shown to be markedly affected by the ionic composition of the medium. A stimulation of the reaction rate at pH 5 was produced by most of the salts tested, which contained anions such as acetate, SO4(2-) and Cl-, and cations such as Na+, K= and Mg2+. The most pronounced effect was observed with MgCl2. Only potassium glutamate was inhibitory. 2. Five peaks of beta-galactosidase activity obtained by DEAE-cellulose chromatography were equally sensitive to changes in the ionic composition of the medium. In the presence of added NaC1, the whole rate-pH curve was displaced towards higher pH values, the optimum being shifted from 2.0-2.5 to 3.5. The stimulation at pH 5.0 appeared to be mainly due to changes in Vmax., whereas the apparent Km was slightly modified. 3. Unlike the total, the free beta-galactosidase activity remained unchanged or even declined when KC1 was added to the reaction medium.

Acetates↗
PubMed1975

Molecular nature of beta-galactosidase from different tissues in two strains of the house mouse.

One inbred mouse strain, C57BL/Kl, has high galactosidase activities in all tissues while another strain, DBA/2/Kl, has low activities determined by the Bgs locus. Beta-Galactosidase from these two strains was partly purified by a five-step procedure: acidification, ammonium sulfate precipitation, gel filtration at two pHs, and isoelectric focusing. No qualitative differences were found between the enzyme preparations from the two strains. They had identical heat inactivation curves, pH optima, molecular weight, and isoelectric points, and the Km values were very similar. It thus seems that this genetic difference in enzyme activity probably cannot be explained by a variation of the galactosidase-specific activity but rather reflects a difference in number of enzyme molecules. Eight different isoenzymes were separated from liver, kidney, and spleen. Each isoenzyme has a different electrophoretic mobility and there is a stepwise increase in molecular weight from 143,000 to 380,000 beginning with the protein having the lowest isoelectric point. A likely interpretation is that the isoenzymes bind a smaller polypeptide in varying numbers in addition to the enzymatic polypeptide per se.

Animals↗
PubMed1976

A quantitation of the factors which affect the hydrolase and transgalactosylase activities of beta-galactosidase (E. coli) on lactose.

A study was implemented to quantitate the hydrolase and transgalactosylase activities of beta-galactosidase (E. coli) with lactose as the substrate and to investigate various factors which affect these activities. At low lactose concentrations the rate of galactose production was equal to the rate of glucose production. The rate of galactose production relative to glucose, however, dropped dramatically at lactose concentrations higher than 0.05 M and production of trisaccharides and tetrasaccharides began (galactose/glucose ratios of about 2:1 and 3:1, respectively, were found for these two types of oligosaccharides). At least five different trissacharides were formed and their patterns of formation showed that they probably utilized both lactose and allolactose as galactosyl acceptors. Allolactose was produced in amounts proportional to glucose at all lactose concentrations (ratios of allolactose/glucose were about 0.88). Analyses of various data, including a reaction analyzed at very early times, showed that the major means of production of allolactose (and the only means initially) was the direct enzymatic transfer of galactose from the 4 position to the 6 position of the glucose moiety of lactose without prior release of glucose from the enzyme. It was shown, however, that allolactose could also be formed in significant quantities by the transfer of galactose to the 6 position of free glucose, and also by hydrolysis of preformed trisaccharide. A mechanism which fits the initial velocity data was proposed in which the steps involving the formation of an enzyme-gallactose-glucose complex, the formation and breakage of allolactose on the enzyme, and the release of glucose all seem to be of roughly equal magnitude and rate determining. Various factors affected the amounts of transgalactosylase and hydrolase activities occurring. At high pH values (greater than 7.8) the transgalactosylase/hydrolyase activity ratio increased dramatically while it decreased at low pH values (less than 6.0). At mid pH values the ratio was essentially constant. The absence of Mg2+ caused a large decrease in the transgalactosylase/hydrolase activity ratio while the absence of all but traces of Na+ or K+ had no effect. The anomeric configuration of lactose altered the transgalactosylase/hydrolase activity ratios, alpha-Lactose resulted in a decrease of allolactose production (transgalactosylase activity) relative to hydrolase activities (glucose production) while beta-lactose had the opposite effect.

Chromatography, Gas↗
PubMedDate not supplied

[Preparation and properties of beta-galactosidase linked covalently with KM-cellulose].

Fungal beta-galactosidase was immobilized by covalent binding with KM-cellulose. The resultant preparation contained 3 mg protein per 1 g carrier; its specific activity was 65% of the initial one. As a result of immobilization pH optimum remained unchanged whereas the temperature optimum decreased from 65 degrees to 50 degrees. The seemings Km of the immobilized enzyme varied insignificantly as compared with Km of the soluble enzyme.

Binding Sites↗
PubMedDate not supplied

Regional study of acid hydrolases and lysosomal membrane properties in the normal human brain at various ages.

Acid hydrolases and lysosomal membrane properties were studied at various ages in the normal human brain. In CSF and four brain regions, the inferior olive, the cerebellar cortex, the caudate nucleus and the frontal cortex were thus beta-galactosidase, beta-glucosidase, alpha-mannosidase, hexosaminidase and acid phosphatase biochemically quantitated at ages varying between 2 and 89 years of age. Also the membrane latency for acid phosphatase was studied in these regions. No major regional quantitative differences were found with regard to the enzymes studied. Their kinetic properties were also defined. There appeared to exist a regional and intra-areal variation in lysosomal membrane permeability. There was, however, no age related increase in total enzyme contents. The possibility significance of these findings are discussed with reference to the aging process.

Acid Phosphatase↗
PubMed1976

The subcellular distribution of adenylate and guanylate cyclases in murine lymphoid cells.

Membrane vesicles can be prepared from murine lymphoid cells by nitrogen cavitation and fractionated by sedimentation through nonlinear sucrose density gradients. Two subpopulations of membrane vesicles, PMI and PMII, can be distinguished on the basis of sedimentation rate. The subcellular distribution of adenylate and guanylate cyclases in these membrane subpopulations have been compared with the distribution of a number of marker enzymes. Approximately 20-30% of the total adenylate and guanylate cyclase activity is located at the top of the sucrose gradient (soluble enzyme), the remainder of the activity being distributed in the PMI and PMII fractions (membrane-bound enzyme). More than 90% of the 5'-nucleotidase and NADH oxidase activities detected in lymphoid cell homogenates are located in PMI and PMII fractions, whereas succinate cytochrome c reductase activity is detected only in the PMII fractions. In addition, beta-galactosidase activity is distributed in the soluble and PMII fractions of the sucrose density gradients. On the basis of the fractionation patterns of these various enzyme activities, it appears that PMI fractions contain vesicles of plasma membrane and endoplasmic reticulum, whereas PMII fractions contain mitochondria, lysomes, and plasma membrane vesicles. Approximately 30-40% of the adenylate and guanylate cyclase activities in PMII can be converted to a PMI-like form following dialysis and resedimentation through a second nonlinear sucrose gradient. Adenylate and guanulate cyclases can be distinguished on the basis of sensitivity to nonionic detergents.

Adenylyl Cyclases↗
PubMed1975

Defective lysosomal enzyme secretion in kidneys of Chediak-Higashi (beige) mice.

The beige mouse is an animal model for the human Chediak-Higashi syndrome, a disease characterized by giant lysosomes in most cell types. In mice, treatment with androgenic hormones causes a 20-50-fold elevation in at least one kidney lysosomal enzyme, beta-glucuronidase. Beige mice treated with androgen had significantly higher kidney beta-glucuronidase, beta-galactosidase, and N-acetyl-beta-D-glucosaminidase (hexosaminidase) levels than normal mice. Other androgen-inducible enzymes and enzyme markers for the cytosol, mitochondria, and peroxisomes were not increased in kidney of beige mice. No significant lysosomal enzyme elevation was observed in five other organs of beige mice with or without androgen treatment, nor in kidneys of beige females not treated with androgen. Histochemical staining for glucuronidase together with subcellular fractionation showed that the higher glucuronidase content of beige mouse kidney is caused by a striking accumulation of giant glucuronidase-containing lysosomes in tubule cells near the corticomedullary boundary. In normal mice lysosomal enzymes are coordinately released into the lumen of the kidney tubules and appreciable amounts of lysosomal enzymes are present in the urine. Levels of urinary lysosomal enzymes are much lower in beige mice than in normal mice. It appears that lysosomes may accumulate in beige mice because of defective exocytosis resulting either from decreased intracellular motility of lysosomes or from their improper fusion with the plasma membrane. A similar defect could account for characteristics of the Chediak-Higashi syndrome.

Alcohol Oxidoreductases↗
PubMed1976

Acid hydrolases in leukocytes and platelets of normal subjects and in patients with Gaucher's and Fabry's disease.

Lymphocytes, monocytes, neutrophilic granulocytes and platelets were each separated to greater than 95% purity from six normal subjects, three patients with Gaucher's disease, two heterozygotes for Gaucher's disease, and one patient with Fabry's disease. Activities of the following acid hydrolases were determined: "acid" (pH 4.0) beta-glucosidase, pH 5.0 beta-glucosidase, alpha-galactosidase, alpha-arabinosidase, alpha-mannosidase, alpha-glucosidase, beta-glucuronidase, beta-galactosidase, beta-hexosaminidase, and acid phosphatase. Enzymatic activity varied greatly with cell type and the enzyme being measured; the importance of assaying pure preparations especially for heterozygote detection is emphasized. Gaucher's disease patients' cells were found to be deficient in the pH 4.0 acid beta-glucosidase, variable in the pH 5.0 beta-glucosidase, and normal in all other acid hydrolases tested, including acid phosphatase, the activity of which is known to be elevated in plasma. Blood cells of a patient with Fabry's disease were deficient in alpha-galactosidase and normal in all other acid hydrolases tested.

Acid Phosphatase↗
PubMed1976

Acid, neutral, and alkaline hydrolases in arthritic synovium.

The levels of six lysosomal enzymes (acid phosphatase, beta-acetylglucosaminidase, cathepsin D, beta-galactosidase, arylsulfatase A, and beta-glucuronidase) and four neutral and alkaline hydrolases (esterase, inorganic phyrophosphatase, alkaline phosphatase, and 5'-nucleotidase) were measured in osteoarthritic, rheumatoid and control synovia. All enzyme levels in diseased synovium except esterase values in osteoarthritis were significantly elevated compared with controls. The mean values of the group of acid hydrolases and the group of neutral and alkaline hydrolases in osteoarthritic synovia were 1.9- and 2.0-fold greater than those of control specimens. In rheumatoid synovia, the values were 4.2- and 4.5 fold greater than control for the same enzymes. Levels in rheumatoid synovia were significantly higher than those in osteoarthritic synovia with the exception of 5'-nucleotidase. Only a limited correlation between the extents of inflammation present in the synovia and the levels of a lysosomal marker enzyme (cathepsin D) was observed. These results demonstrate that whatever the mechanism, increased levels of acid hydrolases as well as certain neutral and alkaline hydrolases are present in osteoarthritic and rheumatoid synovia, and these enzymes are probably contained in the synovial lining cells.

Acetylglucosaminidase↗
PubMed1975

Lysosomal hydrolases of the epidermis. I. Glycosidases.

Seven distinct glycosidases (EC 3.2) have been characterized in guinea-pig epidermis. Their properties indicate them to be of lysosomal origin. The 'profile' of the epidermal glycosidases is significantly different from that reported for whole skin, the activities of beta-galactosidase and beta-acetylglucosaminidase being very high and those of the remaining enzymes relatively low in epidermis.

Acetylglucosaminidase↗
PubMed1976

Effect of long-term starvation on the rat liver lysosomes.

The effect of 120- and 240-h starvation on rats hepatocytes ultrastructure and particularly the changes of the lysosomes were studied. Eelectronmicroscopically and cytochemically there have been observed diminution of the number of mitochondria and degranulation and vacuolzation of the ER. At the same time Golgi complex was hypertrophied and the number of lysosomes was much increased, mainly those of the autophagic type. Biochemically was shown, that the activity of some acid hydrolases (beta-glucosidase, alpha- and beta-galactosidases, beta-N-acetylglucosaminidase, beta-glucuronidase and arylsulphatases A and B) in the liver of starved rats was markedly expressed. The sedimentation properties of the lysosomes and the lysosomal membrane stability was damaged as well. The data received have been discussed in the light of the reconstructive role of lysosomes.

Acetylglucosaminidase↗
PubMed2024

New vectors and optimal conditions for allelic exchange in hypervirulent Klebsiella pneumoniae.

The emergence of antibiotic-resistant Klebsiella pneumoniae is a significant global health threat that has led to increased morbidity and mortality. This resistance also hinders basic research, as many strains are no longer susceptible to antibiotics commonly used in microbial genetics. Addressing this requires the development of new genetic tools with alternative selective markers. In this report, we introduce new allelic exchange vectors for use in drug-resistant strains. These vectors feature a conditional R6K origin of replication, an origin of transfer, SacB counter-selection, and alternative selectable markers. We validated the vectors by generating unmarked deletions in the K. pneumoniae KPPR1S bla (β-lactamase) and lacZ (β-galactosidase) genes. During this process, we defined optimized conditions for SacB-mediated allelic exchange in KPPR1S, significantly enhancing the efficiency of mutant generation. Furthermore, we demonstrated that lacZ is dispensable for virulence and that the lacZ mutant can serve as a surrogate for wild-type strains in competition assays using the Galleria mellonella infection model. Our findings provide new tools for the efficient genetic manipulation of K. pneumoniae and other drug-resistant bacteria.

Klebsiella pneumoniae↗
PubMed2001

A novel eIF2B-dependent mechanism of translational control in yeast as a response to fusel alcohols.

Fusel alcohols are natural products of amino acid catabolism in the yeast Saccharomyces cerevisiae that cause morphological changes similar to those seen during pseudohyphal growth. We have discovered that certain of these alcohols, including butanol and isoamyl alcohol, bring about a rapid inhibition of translation at the initiation step. This inhibition is strain specific and is not explained by previously described translational control pathways. Using genetic mapping, we have identified a proline to serine allelic variation at amino acid 180 of the GCD1 gene product as the genetic locus that allows translational regulation upon butanol addition. Gcd1p forms part of the eIF2B guanine nucleotide complex that is responsible for recycling eIF2-GDP to eIF2-GTP. This represents one of the key limiting steps of translation initiation and we provide evidence that fusel alcohols target eIF2B in order to bring about translational regulation.

Alcohols↗
PubMed2026

Trimming galactose side chains of arabinogalactan proteins alters pectin and hemicellulose deposition in secondary cell walls of Arabidopsis thaliana floral stem internodes.

Shaping the cell wall composition and structure to meet the requirements of different tissues and developmental stages relies on multiple actors, including arabinogalactan proteins (AGPs). Although the specific role of these proteins in cell wall dynamics is still under debate, especially in events involving significant remodeling of the cell wall, their carbohydrate motif, type II arabinogalactan (AGII), seems to be crucial for their function. This study aims to investigate the function of AGII, specifically the galactose residues of its side chains, in the structural organization of the cell wall during the cessation of elongation and the transition to secondary growth. To achieve this, we characterized floral stem internodes of Arabidopsis thaliana plants overproducing the chickpea βV-galactosidase protein (35S::βV-Gal plants), an enzyme that specifically hydrolyzes the β-(1,3)- and β-(1,6)-galactosyl residues of AGII. Changes induced in the cell wall by trimming galactose residues of AGII resulted in a noticeable increase in homogalacturonan methyl esterification. Additionally, these neutral galactose side chains may regulate hemicellulose-cellulose interactions and influence xylan distribution through the cellulose network, which in turn affects the deposition of lignin and determines its recalcitrance to enzymatic degradation.

Arabidopsis↗
PubMed2026

Rhodoglobus galactosidasius sp. nov., a psychrophilic Actinomycetota producing a cold-active β-galactosidase isolated from Cape Hallett, Antarctica.

A novel psychrophilic member of the phylum Actinomycetota, designated strain CPHL_1T, was isolated from the shoreline of Cape Hallett, Antarctica. Cells were Gram-positive, aerobic, non-motile, non-spore-forming rods (0.7-1.0 µm in length) with orange to yellow pigmentation. Optimal growth occurred at 15 °C, pH 8.0, with NaCl tolerance up to 3% (w/v). Strain CPHL_1T exhibited cytosolic cold-active β-galactosidase activity, with an optimum at 15 °C and pH 7.0 and formed non-adherent biofilms. Phylogenetic analysis based on 16S rRNA gene sequence placed the strain within the genus Rhodoglobus, showing high similarity to Rhodoglobus vestalii LV3T (99.4%) and Rhodoglobus aureus CMS 81yT (97.6%). Chemotaxonomic characteristics, including the predominance of anteiso-C15 : 0, anteiso-C17 : 0 and iso-C16 : 0 fatty acids, the presence of MK-11, MK-10 and MK-12 as the major respiratory quinones, and genomic G+C content of 60%, further supported its assignment to the genus Rhodoglobus. Whole-genome comparisons revealed clear taxonomic distinction, with strain CPHL_1T sharing 88.9% average nucleotide identity (ANI) and 38.3% digital DNA-DNA hybridization (dDDH) values with R. aureus, and 81.7% ANI and 25.1% dDDH with R. vestalii, confirming its status as a novel species. Phylogenetic analysis revealed that the β-galactosidases from these Rhodoglobus strains form a well-supported clade with high sequence similarity. Based on these data, a novel species is proposed: Rhodoglobus galactosidasius sp. nov. (type strain CPHL_1T =ITEM 19986T =KCTC 59592T). Genomic analyses also highlighted its biosynthetic potential for specialized metabolites, consistent with the recognized metabolic diversity of the genus.

Phylogeny↗
PubMed2005

Molecular determinants for PspA-mediated repression of the AAA transcriptional activator PspF.

The Escherichia coli phage shock protein system (pspABCDE operon and pspG gene) is induced by numerous stresses related to the membrane integrity state. Transcription of the psp genes requires the RNA polymerase containing the sigma(54) subunit and the AAA transcriptional activator PspF. PspF belongs to an atypical class of sigma(54) AAA activators in that it lacks an N-terminal regulatory domain and is instead negatively regulated by another regulatory protein, PspA. PspA therefore represses its own expression. The PspA protein is distributed between the cytoplasm and the inner membrane fraction. In addition to its transcriptional inhibitory role, PspA assists maintenance of the proton motive force and protein export. Several lines of in vitro evidence indicate that PspA-PspF interactions inhibit the ATPase activity of PspF, resulting in the inhibition of PspF-dependent gene expression. In this study, we characterize sequences within PspA and PspF crucial for the negative effect of PspA upon PspF. Using a protein fragmentation approach, we show that the integrity of the three putative N-terminal alpha-helical domains of PspA is crucial for the role of PspA as a negative regulator of PspF. A bacterial two-hybrid system allowed us to provide clear evidence for an interaction in E. coli between PspA and PspF in vivo, which strongly suggests that PspA-directed inhibition of PspF occurs via an inhibitory complex. Finally, we identify a single PspF residue that is a binding determinant for PspA.

Bacterial Proteins↗