Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.2.1.23 (beta-galactosidase)
14,648 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The sequence of the COOH-terminal third (omega) of beta-galactosidase is presented. The size of the 7 cyanogen bromide peptides of this segment is larger on the average, about 52 amino acid residues as compared to an average size of 42 for cyanogen bromide peptides in the whole molecule. Tyrosine, phenylalanine, and valine are low in this segment whereas alanine and lysine are high. This region has a slight excess of basic groups.
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PMID:Amino acid sequence of beta-galactosidase. X. Sequence of the COOH-terminal segment, CNBr peptides 18 to 24, residues 654 to 1021. 9 97

Amino-acid analyses on the acid hydrolysates of an angiofibroma and skin established that the former tissue contained less collagen than skin based on the reduced content of hydroxyproline, glycine, proline and alanine in the tumour. From lysosomal enzyme measurements it became evident that the specific activities of the hexosaminidases, beta-glucuronidase and beta-galactosidase were elevated. Analyses of the alcohol insoluble fraction following pronase digestion revealed that the tumour contained more acidic glycosaminoglycan (AG) than skin as assessed by uronic acid and hexosamine measurements. More outstanding, however, was the seven-fold increase in the total carbohydrate in the AG fraction of the tumour. The overall composition of this fraction was very similar to comparable material from foetal skin except that the tumour fraction contained increased sulphate concentration.
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PMID:Chemical analysis of an angiofibroma from a patient with tuberous sclerosis. 20 95

The amino acid sequence of beta-galactosidase was determined. The protein contains 1021 amino acid residues in a single polypeptide chain. The subunit molecular weight calculated from the sequence is 116,248. The sequence determination, carried out mainly by conventional methods, was aided by complementation tests, by the use of termination mutant strains, and by a new immunochemical method. The five residue sequence Thr-Pro-His-Pro-Ala appears twice within the polypeptide chain, but no other striking homologous features are evident.
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PMID:The amino acid sequence of beta-galactosidase of Escherichia coli. 32 55

Intracistronic alpha-complementation between a cyanogen bromide digest of beta-galactosidase and an extract of the lac Zminus operator-proximal deletion mutant M15 was used to monitor the purification of a cyanogen bromide peptide (CB2) responsible for the complementation. Key steps in the purification were ion exchange chromatography on carboxymethylcellulose and sulfopropyl-Sephadex in the presence of urea, and Sephadex gel filtration. CB2 contains residues 3 to 92 of beta-galactosidase. Its sequence is: Ile-Thr-Asp-Ser-Leu-Ala-Val-Val-Leu-Gln-Arg-Arg-Asp-Trp-Glu-Asn-Pro-Gly-Val-Thr-Gln-Leu-Asn-Arg-Leu-Ala-Ala-His-Pro-Pro-Phe-Ala-Ser-Trp-Arg-Asn-Ser-Glu-Glu-Ala-Arg-Thr-Asp-Arg-Pro-Ser-Gln-Gln-Leu-Arg-Ser-Leu-Asn-Gly-Glu-Trp-Arg-Phe-Ala-Trp-Phe-Pro-Ala-Pro-Glu-Ala-Val-Pro-Glu-Ser-Trp-Leu-Glu-Cys-Asp-Leu-Pro-Glu-Ala-Asp-Thr-Val-Val-Val-Pro-Ser-Asn-Trp-Gln-Met. Thus no more than 1/13 of the beta-galactosidase polypeptide chain, starting 2 residues from the NH2 terminus, is necessary for alpha-complementation with M15 as alpha-acceptor.
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PMID:Amino acid sequence of beta-galactosidase. IV. Sequence of an alpha-complementing cyanogen bromide peptide, residues 3 to 92. 109 37

A mutant of Escherichia coli is described whose cells show a spherical or irregular morphology, associated with leakage of beta-galactosidase and other intracellular proteins. The expression of the morphologic abnormality is most marked when the mutant is grown in rich media and is suppressed by D-alamine, D-serine, D-glutamate, or glycine supplementation. D-Alanine is the most effective amino acid supplement, half maximally supressing this anomalous property at a concentration of 75 mug/ml, as measured by the reduction in beta-galactosidase released from the cells. The mutant is more sensitive to penicillin G, D-methionine, and D-valine and it is relatively resistant to lysozyme. These phenotypic abnormalities are likewise corrected by the above supplementations. The relative rates of peptidoglycan synthesis in mutant and parent, grown under restrictive conditions, were measured both in vivo and in vitro by rates of incorporation of L-[14-D]alanine and uridine-5'-diphosphate-N-acetyl-D-[1-15C-A1-glucosamine, respectively. There is not metabolic block in the biosynthesis of uridine-5'-diphosphate-N-acetyl-muramyl-pentapeptide as shown by enzymic analysis and the lack of accumulation of uridine-5'-diphosphate-N-acetylmuramyl-peptide precursors. These preliminary studies suggest that the mutant possesses a defect in the biosynthesis of peptidoglycan although the exact lesion has not yet been established.
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PMID:D-Alanine-requiring cell wall mutant of Escherichia coli. 109 98

The human 72-kDa (CLG4A) and 92-kDa (CLG4B) type IV collagenases contain a domain consisting of three contiguous copies of the fibronectin (FN)-derived type II homology unit (T2HU), T2HU-1, T2HU-2, and T2HU-3. To investigate the functional role of this domain, we have constructed plasmids expressing beta-galactosidase fusion proteins with one or more of the CLG4B-derived T2HU. The gelatin binding assays demonstrate that a single copy of T2HU-2 renders beta-galactosidase capable of binding gelatin. The three repeats, however, differ dramatically in their capacity to bind gelatin, with T2HU-1 and T2HU-3 having significantly less binding activity than T2HU-2. Using alanine scanning mutagenesis we have defined the amino acid residues (Arg307, Asp309, Asn319, Tyr320, Asp323) that are critical for gelatin binding of T2HU-2. The low gelatin binding of T2HU-1 compared to T2HU-2 was traced to the non-conserved residues Ala228-Ala and Leu253-Pro. The results suggest that the gelatin binding of the type IV collagenase proenzyme is mediated by the FN-like domain, although the presence of another gelatin-binding site cannot be excluded. The FN domain-mediated binding, however, is not a rate-limiting step in the hydrolysis of gelatin by the enzyme.
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PMID:Alanine scanning mutagenesis and functional analysis of the fibronectin-like collagen-binding domain from human 92-kDa type IV collagenase. 131 21

Urinary dilution adjustment methods can be used to reduce the intra-individual variability in concentrations of metals and other substances in urine due to variability in urinary flow. In this study linear and non-linear dilution adjustments with urinary flow, creatinine (CREAT) and urinary density (UD) were compared for the urinary enzymes alanine amino peptidase (AAP), beta-galactosidase (beta GAL) and N-acetyl-beta, D-glucosaminidase (NAG). The most optimal dilution adjustment for AAP was: AAPadjusted = AAPmeasured/(CREATmeasured)0.824 The optimal dilution adjustment for beta GAL was: beta GALadjusted = beta GALmeasured/(CREATmeasured)0.878 For NAG the optimal dilution adjustment parameter was the conventional linear adjustment with SG. It could not be determined whether urinary dilution methods can be useful for population based reference intervals of urinary enzymes. If personal reference intervals can be calculated, urinary dilution adjustment methods may be useful by reduction of intraindividual variability.
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PMID:A comparison of dilution adjustment methods for urinary enzymes. 135 36

Biotinylation of fusion proteins in E. coli was studied using a sequence of Propionibacterium freudenreichii transcarboxylase 1.3S biotin subunit. As the biotinylation sequence, we examined two sequences: one was of amino acid residues [84-123] of 1.3S, a partial sequence containing a region from a conserved tetrapeptide (Ala-Met-Bct-Met) around the biotinyl lysine (Bct) to the carboxyl terminal; the other was of an almost entire sequence [18-123]. We constructed recombinant plasmids for fusion proteins of beta-galactosidase, of chloramphenicol acetyltransferase, and of alkaline phosphatase. We found the biotinylation in the [18-123] sequence fused to alkaline phosphatase.
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PMID:In vivo biotinylation of fusion proteins expressed in Escherichia coli with a sequence of Propionibacterium freudenreichii transcarboxylase 1.3S biotin subunit. 136 26

The Avi-3 antigen, which is found only in Mycobacterium avium culture sonic extracts, is species specific and results in strong skin test activity in guinea pigs sensitized with heat-killed M. avium. Its gene was cloned by using a previously developed single-probe method and was sequenced. The gene encoded a 194-amino-acid polypeptide with a molecular weight of 21,500. A recombinant Avi-3 antigen expressed in Escherichia coli reacted with monoclonal and polyclonal antibodies raised against the native Avi-3 antigen. To identify epitopes on this protein for immunodiagnostic purposes, various parts of the Avi-3 antigen were expressed as beta-galactosidase fusion proteins, using pUR and pURS expression vectors. The clones screened by both antibody reactivity and T-cell proliferative activity defined fragments with coexisting B- and T-cell epitopes. A B-cell epitope (Asn-176 to Ala-186) and two T-cell epitopes (Glu-75 to Ile-86 and Arg-155 to Leu-164) were thus defined. The synthetic polymerized peptides of the T-cell epitopes were proven to elicit a delayed cutaneous hypersensitivity reaction in guinea pigs. This mapping method would be useful in the development of a subunit vaccine consisting of an immunodominant B-cell epitope linked to a T-cell epitope in the vicinity.
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PMID:Cloning and expression of the gene for the Avi-3 antigen of Mycobacterium avium and mapping of its epitopes. 137 65

Although it is energetically extremely unfavorable to have charged amino acid residues of a polypeptide in the hydrophobic environment of the membrane phospholipid bilayer, a few such charged residues are found in membrane-spanning regions of membrane proteins. Ion pairs (salt bridges) would be much more stable in low dielectric media than single ionized residues. This paper provides indirect evidence for a salt bridge between Asp-240 and Lys-319 in the lactose carrier of Escherichia coli. When Asp-240 was changed to alanine by site-directed mutagenesis, there was a loss of the ability to accumulate methyl-beta-D-thiogalactopyranoside (TMG), melibiose, or lactose. Fast-growing revertants were isolated on melibiose minimal agar plates. Two second-site revertants were isolated: Asp-240-->Ala plus Gly-268-->Val and Asp-240-->Ala plus Lys-319-->Gln. These revertants showed extremely poor accumulation of TMG, melibiose, and lactose, but showed significant "downhill" lactose entry into beta-galactosidase-containing cells with sugar concentrations of 2 and 5 mM. It is concluded that there is some important interaction between Asp-240 and Lys-319, possibly a salt bridge.
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PMID:Possible salt bridges between transmembrane alpha-helices of the lactose carrier of Escherichia coli. 140 Mar 92


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