Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.2.1.23 (beta-galactosidase)
 14,648 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Production of beta-galactosidase by Sclerotium rolfsii NCIM 1084 was studied under submerged fermentation conditions. The enzyme was produced extracellularly and constitutively on glucose. The enzyme production was enhanced when galactose, raffinose, cellobiose, sucrose, xylose, maltose, cellulose and pectin were used as carbon sources. Cellulose and diammonium hydrogen phosphate were best carbon and nitrogen sources, respectively. Surfactants such as Sag, Paraffin oil, Tween 20 and Tween 80 increased the enzyme production. Maximum yield of beta-galactosidase obtained was 3.8-4.2 nkat/ml. The optimum pH, optimum temperature and molecular weight of the beta-glactosidase were 2.7, 60 degrees C and 2,21,000 daltons, respectively. The enzyme is an aryl beta-glactosidase and did not hydrolyse lactose. The Km value for o-nitrophenyl beta-D-galactoside was 3.7 mM. Galactose and 2-mercaptoethanol inhibited the enzyme.
 ...
PMID:Aryl beta-galactosidase from Sclerotium rolfsii: physiological and biochemical studies. 897 38

A series of gel filtration, native polyacrylamide gel electrophoresis (PAGE) and sucrose density experiments showed that uncomplemented M15 beta-galactosidase is in a monomer-dimer equilibrium and that only under some specific conditions does the equilibrium strongly favor dimerization. The ratio of dimer to monomer increased as a function of the protein concentration, and a very good fit to a theoretical plot of the effect of protein concentration on an associating system of this type was found. The Kdiss (equilibrium constant for dimer dissociation) was 2.5 x 10(-7) M. The addition of 20 mM Mg2+ lowered the Kdiss to 1.5 x 10(-7) M, and the addition of 150 mM NaCl lowered the value to 0.4 x 10(-7) M. Thiol reagents (2-mercaptoethanol and dithiothreitol) caused the equilibrium to shift totally to the dimeric form. The monomer-dimer equilibrium was also found to be dependent upon the pH. The dissociation increased as the pH was raised to 8.5, but there was a reversal of the equilibrium in favor of dimer formation at pH 9.0. This suggests that one (or more) residues with a pKa value of about 8.0 is involved. Tyr and Lys were eliminated as possible residues involved and it is, therefore, likely that one or more Cys are involved. Further evidence that uncomplemented M15 beta-galactosidase is in a monomer-dimer equilibrium was that the gel-filtration peaks were not totally resolved and that native PAGE bands were diffuse under all conditions except at high thiol concentration.
 ...
PMID:Monomer-dimer equilibrium of uncomplemented M15 beta-galactosidase from Escherichia coli. 906 75

Lack of permissive and productive cell cultures for the human papillomaviruses (HPVs) has hindered the study of virus-neutralizing antibodies and infection. We developed a cell-free system generating infectious HPV16 pseudovirions. HPV16 L1/L2 capsids, which had been self-assembled in insect cells (Sf9) expressing virion proteins L1 and L2, were disassembled with 2-mercaptoethanol (2-ME), a reducing agent, and reassembled by removal of 2-ME in the presence of a beta-galactosidase expression plasmid. Plasmid DNA purified together with the reassembled capsids was resistant to DNase I digestion. The reassembled pseudovirions mediated DNA transfer to COS-1 cells, as monitored by induced beta-galactosidase activity. Transfer was inhibited by anti-HPV16 L1 antiserum but not by antisera against L1s of HPV6 and HPV18. Construction in vitro of HPV pseudovirions containing marker plasmids would be potentially useful in developing methods to assay virus-neutralizing antibodies and to transfer exogenous genes to HPV-susceptible cells.
 ...
PMID:In vitro construction of pseudovirions of human papillomavirus type 16: incorporation of plasmid DNA into reassembled L1/L2 capsids. 981 79

M15 beta-galactosidase (Escherichia coli) is a mutant form of beta-galactosidase having residues 11-41 deleted. It is an inactive dimer but can be complemented to the active tetrameric form by the addition of a peptide containing the deleted residues. The activities of uncomplemented and complemented M15 beta-galactosidases decreased starting at 42 degrees C--uncomplemented over a narrow temperature range, complemented over a broad range. This is because uncomplemented protein is a simple dimer while complemented is a mix of interacting oligomers at high temperatures. The effects of added components on stability and alpha-complementation are best explained by binding effects on equilibria between native forms and forms susceptible to inactivation. Mg2+ stabilized complemented protein but destabilized uncomplemented protein (10x less Mg2+ was needed for complemented protein). Alpha-complementation increased somewhat at low Mg2+ but decreased at high Mg2+. These effects can be explained by differential Mg2+ binding to the native and susceptible forms. The enhancement of both stability and alpha-complementation by Na+ can be explained by preferential binding of Na+ to the native forms of both the uncomplemented and complemented proteins. Low 2-mercaptoethanol concentrations stabilized uncomplemented M15 beta-galactosidase, but high concentrations destabilized it. All concentrations destabilized complemented M15 beta-galactosidase. Alpha-complementation was enhanced by 2-mercaptoethanol. Thus, there is a correlation between stability of the uncomplemented protein and alpha-complementation at low 2-mercaptoethanol owing to interactions with native forms. The lack of correlation at higher 2-mercaptoethanol probably results from precipitation by 2-mercaptoethanol. In contrast to irreversible thermal inactivation, differences in reversible stability in urea were small. This suggests that quaternary structure and Mg2+ and Na+ sites are lost at low urea concentrations and are unimportant at the urea concentrations that result in reversible denaturation.
 ...
PMID:Stabilities of uncomplemented and complemented M15 beta-galactosidase (Escherichia coli) and the relationship to alpha-complementation. 1043 45

beta-Galactosidase catalyzed beta-galactosylation not only of a hydroxyl group but also of a thiol group in the condensation reaction of D-galactose and 2-mercaptoethanol. The thio-galactosylation product was confirmed as 2-hydroxyethyl S-beta-D-galactoside on the bases of fast atom bombardment mass spectrometry, infrared spectroscopy, and nuclear magnetic resonance spectorometry. Aspergillus oryzae beta-galactosidase hydrolyzed p-nitrophenyl S-beta-D-galactoside most rapidly among several beta-galactosidases and produced the thio-galactosylation product most efficiently. The Penicillim multicolor enzyme was as effective as the A. oryzae enzyme. However the enzymes from Escherichia coli, Saccharomyces fragilis, Kluyveromyces lactis, and Bacillus circulans galactosylated hydroxyl groups predominantly to produce O-galactoside. The thio-galactoside was synthesized most effectively at a 2-mercaptoethanol concentration of about 1.25 M. Galactose concentration at 0.8-2.8 M did not affect the synthetic yield of the thiogalactoside so greatly.
 ...
PMID:Galactosylation of thiol group by beta-galactosidase. 1083 Apr 85

We have shown previously that a 'soluble' form of PrP (prion protein), not associated with membranous vesicles, exists in the male reproductive fluid [Ecroyd, Sarradin, Dacheux and Gatti (2004) Biol. Reprod. 71, 993-1001]. Attempts to purify this 'soluble' PrP indicated that it behaves like a high-molecular-mass complex of more than 350 kDa and always co-purified with the same set of proteins. The main associated proteins were sequenced by MS and were found to match to clusterin (apolipoprotein J), BPI (bacterial permeability-increasing protein), carboxylesterase-like urinary excreted protein (cauxin), beta-mannosidase and beta-galactosidase. Immunoblotting and enzymatic assay confirmed the presence of clusterin and a cauxin-like protein and showed that a 17 kDa hydrophobic epididymal protein was also associated with this complex. These associated proteins were not separated by a high ionic strength treatment but were by 2-mercaptoethanol, probably due to its action on reducing disulphide bonds that maintain the interaction of components of the complex. Our results suggest that the associated PrP retains its GPI (glycosylphosphatidylinositol) anchor, in contrast with brain-derived PrP, and that it is resistant to cleavage by phosphatidylinositol-specific phospholipase C. Based on these results, the identity of the associated proteins and the overall biochemical properties of this protein ensemble, we suggest that 'soluble' PrP can form protein complexes that are maintained by hydrophobic interactions, in a similar manner to lipoprotein vesicles or micellar complexes.
 ...
PMID:The epididymal soluble prion protein forms a high-molecular-mass complex in association with hydrophobic proteins. 1602 66

A psychrotrophic bacterium producing a cold-adapted beta-galactosidase upon growth at low temperatures was classified as Arthrobacter sp. 20B. A genomic DNA library of strain 20B introduced into Escherichia coli TOP10F' and screening on X-Gal (5-bromo-4-chloro-3-indolyl-beta-D-galactopyranoside)-containing agar plates led to the isolation of beta-galactosidase gene. The beta-galactosidase gene (bgaS) encoding a protein of 1,053 amino acids, with a calculated molecular mass of 113,695 kDa. Analysis of the amino acid sequence of BgaS protein, deduced from the bgaS ORF, suggested that it is a member of the glycosyl hydrolase family 2. A native cold-adapted beta-galactosidase was purified to homogeneity and characterized. It is a homotetrameric enzyme, each subunit being approximately 116 kDa polypeptide as deduced from native and SDS-PAGE, respectively. The beta-galactosidase was optimally active at pH 6.0-8.0 and 25 degrees Celsius. P-nitrophenyl-beta-D-galactopyranoside (PNPG) is its preferred substrate (three times higher activity than for ONPG-o-nitrophenyl-beta-D-galactopyranoside). The Arthrobacter sp. 20B beta-galactosidase is activated by thiol compounds (53% rise in activity in the presence of 10 mM 2-mercaptoethanol), some metal ions (activity increased by 50% for Na(+), K(+) and by 11% for Mn(2+)) and inactivated by pCMB (4-chloro-mercuribenzoic acid) and heavy metal ions (Pb(2+), Zn(2+), Cu(2+)).
 ...
PMID:A new beta-galactosidase with a low temperature optimum isolated from the Antarctic Arthrobacter sp. 20B: gene cloning, purification and characterization. 1977 12


<< Previous 1 2