Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:4.1.2.42 (DTA)
 1,693 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have constructed hybrid proteins in which the toxic A chains of ricin or diptheria toxin have been linked to either asialofetuin, fetuin, or epidermal growth factor (EGF). Both ASF-RTA and ASF-DTA are potent toxins on cultured rat hepatocytes, cells that display the asialoglycoprotein receptor. Toxicity of these two compounds is restricted to hepatocytes and can be blocked by asialoglycoproteins but not the native glycoproteins or asialoagalactoglycoprotein derivatives, indicating that the toxicity of the conjugates is mediated by the hepatic asialoglycoprotein receptor. The EGF-RTA conjugate is an extremely potent toxin on cells that can bind the hormone, but is only poorly effective on cells that are unable to bind EGF. The EGF-DTA conjugate, in contrast, is unable to kill 3T3 cells and is at least two orders of magnitude less effective than EGF-RTA on A431 cells, a cell line with 1-2 X 10(6) EGF receptors per cell. However, when EGF-RTA and EGF-DTA were tested on primary liver hepatocyte cultures, which were susceptible to both ASF-RTA and ASF-DTA, both EGF conjugates were potent toxins. Sensitivity of the hepatocyte cultures to ricin toxicity increases slightly during a 52-hr culture period. In contrast, sensitivity to EGF-RTA and ASF-RTA decline dramatically during this period. Receptors for both ligands remain plentiful on the cell surface during this time.
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PMID:Toxic ligand conjugates as tools in the study of receptor-ligand interactions. 618 58

Neoglycoalbumin (NGA), a special ligend of asialoglycoprotein receptor on the hepatocyte, was linked via a butanediacyl bridge to acyclovir to form a conjugate NGA-ACV. By using DTA (Differential thermoanalysis) and HPLC analysis, ACV was shown to be connected with NGA by covalent bonds and stable in blood. The radio-biodistribution of 131I-NGA-ACV with high drug density in vivo was carried out in mice. The maximum absorption of 131I-NGA-ACV in liver was 81.7 +/- 10.4% at 5 min. The radioimage of 131I-NGA-ACV with high or low drug density in rabbit showed no significant difference in liver targeting property. The competitive connection tests indicated that 131I-NGA-ACV was concentrated in liver through receptor mediated mechanism. A tentative test of antihepatitis B of NGA-ACV and ACV in vitro showed that the effective dose of the former was significantly lower than that of the latter.
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PMID:[Preparation of hepatic targeting antivirus agent NGA-ACV and its targeting property]. 977 5