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)

Chemical conjugates of recombinant soluble CD4 (sCD4) with toxins, or with antibodies that activate cytotoxic T cells, can be used to direct selective killing of human immunodeficiency virus (HIV)-infected cells. This approach takes advantage of the ability of sCD4 to bind with high affinity to gp120, the envelope protein of HIV-1, which is expressed on actively infected cells. However, conjugation of sCD4 via reagents that target amino groups may reduce its affinity for gp120, since at least one such group is important for gp120 binding. Here, we describe a novel cross-linking reagent which enables the conjugation of sCD4 via its carbohydrate moieties rather than its free amino groups. This heterobifunctional reagent, 4-(4-N-maleimidophenyl)butyric acid hydrazide (MPBH), combines a nucleophilic hydrazide with an electrophilic maleimide, thereby allowing coupling of carbohydrate-derived aldehydes to free thiols. We describe conditions by which MPBH is coupled selectively to the sialic acid residues of sCD4, and exemplify the use of MPBH by conjugating sCD4 to hemoglobin and to beta-galactosidase. We show that, whereas conjugation of sCD4 via amino groups markedly reduces its gp120 binding affinity, conjugation via the carbohydrate chains using MPBH does not affect binding. Moreover, we demonstrate the ability of a sCD4-MPBH-fluorescein conjugate to label HIV-infected human CEM cells selectively. These results indicate that, by targeting its carbohydrate moieties, sCD4 can be cross-linked to other molecules without compromising its function. The approach described here can be useful for glycoproteins in which amino groups, but not carbohydrates, are important for function. More generally, this approach can be considered for use in cross-linking glycoconjugates to compounds which either contain thiols, or to which thiols can be added.
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PMID:Conjugation of soluble CD4 without loss of biological activity via a novel carbohydrate-directed cross-linking reagent. 163 20

Because metallothionein (MT) is elevated and may be protective in UV-irradiated skin, we have studied the effects of UV and other agents on MT transcription using the sheep MT 1A promoter, linked to the beta-galactosidase gene and stably transfected into human cell lines. beta-galactosidase reporter activity was inducible by adding Zn2+ ions to the medium (100 microM for 2-4 h). Two differentiating agents, butyric acid and azelaic bishydroxamic acid (ABHA), significantly increased the response to Zn2+ in a melanoma cell line (MM96L-gal). UVB (280-315 nm) had two distinct, time-dependent effects. During the first 4 h after irradiation, high doses of UVB inhibited induction by Zn2+, an effect that was made more acute by simultaneous exposure to the differentiating agents. These changes in reporter activity were not due to alterations in Zn2+ transport into the cell. The UVB-depressed MT response subsequently recovered and by 24 h was double the control, yet remained sensitive to ABHA. Reporter activity in transfected HeLa cells differed from that in MM96L, being depressed 4 and 24 h after UVB and insensitive to ABHA at both times. Galactosidase reporter activity driven by non-MT promoters was not affected by these treatments. Dependence of MT transcriptional activity on UV-related DNA damage could be inferred because equitoxic UVC (254 nm) affected the response to Zn2+ in a similar fashion, whereas UVA, cisplatin and a methylating agent had no effect. The MT response was partly dependent on the PKC signal transduction pathway because it was inhibited by phorbol ester in HeLa, and by bisindolyl maleimide in HeLa and MM96L. The biphasic MT transcriptional response may model a signal transduction pathway that gives an early, depressed response to acute UV damage, with exacerbation by concurrent differentiation stimuli, but switches to a positive, cell-specific and potentially protective response at later times.
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PMID:Biphasic response of the metallothionein promoter to ultraviolet radiation in human melanoma cells. 907 40

Lactobacillus acidophilus 74-2, which is used in probiotic products, was administered, with fructo-oligosaccharide in a milk-based product, to the second vessel (duodenum/jejunum) of the SHIME reactor, an in vitro simulation of the human intestinal microbial ecology. The main focus of this study was to monitor the changes of the population density of selected bacterial species in the intestine and the changes of metabolic activities during the supplementation of L. acidophilus and fructooligosaccharide in the SHIME reactor. Interestingly, the addition of L. acidophilus 74-2 with fructooligosaccharide gave rise to an increase of bifidobacteria. Moreover, major positive changes occurred in the production of volatile fatty acids: a strong upward trend was observed especially in the case of butyric acid and propionic acid. Furthermore a noticeable increase of beta-galactosidase activity was monitored, while the activity of beta-glucuronidase, generally considered undesirable, declined.
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PMID:Influence of a synbiotic mixture consisting of Lactobacillus acidophilus 74-2 and a fructooligosaccharide preparation on the microbial ecology sustained in a simulation of the human intestinal microbial ecosystem (SHIME reactor). 1070 85

A new species, Porphyromonas gulae sp. nov., is proposed to include strains isolated from the gingival sulcus of various animal hosts which are distinct from related strains of Porphyromonas gingivalis of human origin. This bacterium exhibits the following characteristics: black-pigmented colonies; asaccharolytic, obligate anaerobic growth; and Gram-negative, non-motile and non-spore-forming, rod-shaped cells. Colonies do not fluoresce under UV light. Vitamin K1 and haemin are required for growth. Cells haemagglutinate sheep erythrocytes. Major fatty acid end products are butyric acid, isovaleric acid, succinic acid and phenylacetic acid. Strains are catalase-positive and indole is produced. Alkaline phosphatase, trypsin-like and N-acetyl-beta-glucosaminidase activities are strong. A beta-galactosidase and a glutamylglutamic acid arylamidase are also present. The G+C content of the chromosomal DNA is 51 mol%. DNA-DNA homology data and 16S rRNA gene sequence analysis provide strong evidence that strains from the animal biotype of P. gingivalis represent a Porphyromonas species that is distinct from P. gingivalis. The type strain of P. gulae is Loup 1T (= ATCC 51700T = NCTC 13180T).
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PMID:Porphyromonas gulae sp. nov., an anaerobic, gram-negative coccobacillus from the gingival sulcus of various animal hosts. 1141 86