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
Query: UNIPROT:P50583 (
asymmetrical
)
12,197
document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)
The different patterns of enzymatic cleavage of diadenosine polyphosphates, ApnAs, where n = 3-5, have been established by fast atom bombardment mass spectrometry,
FAB
MS, of the nucleotide products formed in the presence of H2(18)O. The three specific pyrophosphohydrolases, Ap3A hydrolase (EC 3.6.1.29) and (
asymmetrical
)
Ap4A hydrolase
(EC 3.6.1.17) from lupin and the (symmetrical)
Ap4A hydrolase
(EC 3.6.1.41) from Escherichia coli, manifest three different regiospecificities. The Ap3A hydrolase cleaves all four substrates tested, Ap3A, Ap4A, ApCH2ppA, and ApCHFppA, to give [18O]AMP and the corresponding unlabeled adenosine nucleotide. In each case, the enzyme cleaves at the phosphate proximate to the bound adenosine moiety. The (
asymmetrical
)
Ap4A hydrolase
cleaves both Ap4A and Ap5A to give unlabeled ATP plus [18O]AMP and [18O]ADP, respectively, and is thus seen to add water at the fourth phosphate from the bound adenosine moiety. Lastly, the (symmetrical)
Ap4A hydrolase
from E. coli gives beta-[18O]ADP from Ap3A, Ap4A, and Ap5A along with the unlabeled nucleotide coproducts. In addition, with Ap4A alpha S (ApspppA) as substrate for the bacterial enzyme, the products are beta-[18O]ADP and unlabeled ADP alpha S. This symmetrical enzyme is thus characterized as cleaving the polyphosphate chain at the second phosphate from the bound adenosine moiety.
...
PMID:Regiospecificity of the hydrolysis of diadenosine polyphosphates catalyzed by three specific pyrophosphohydrolases. 828 47
New cationic 99Tc/99Tc complexes formed with various symmetrical and
asymmetrical
vicinal dioximes of different carbon chain length (C5-C8) were synthesized by reduction of pertechnetate with BH4-, separated by HPLC and characterized by i.r./u.v./vis. spectroscopy,
FAB
mass spectrometry and electrophoresis. All complexes studied are trisdioximes containing boron as a constituent. Their lipophilicity, as assessed by the octanol/saline partition coefficient, ranges over almost four orders of magnitude. The myocardial uptake of the 99mTc complexes in mice proves to be lower than expected. The organ distributions are distinctly affected by the lipophilicity, the position of the dioxime group and the introduction of a terminal methoxy group.
...
PMID:Preparation, characterization and biological evaluation of cationic 99Tc/99mTc-dioxime complexes. 848 91
