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Query: UMLS:C0027960 (mole)
 21,279 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A survey of the major deoxyribonucleases in Pseudomonas aeruginosa strain PAO was undertaken. Two activities predominated in Brij-58 lysates of this organism. These have been purified from contaminating nuclease activities, and some of their properties have been elucidated. The first was a nuclease that degraded heat-denatured deoxyribonucleic acid (DNA) to mono- and dinucleotides. The activity of this enzyme was confined to single-stranded DNA, and 100% of the substrate was hydrolyzed to acid-soluble material. The Mg2+ optimum is low (1 to 3mM), and the molecular weight is 6 X 10(4). The second predominant activity was an adenosine 5'-triphosphate (ATP)-dependent deoxyribonuclease. This enzyme had an absolute dependence on the presence of ATP Mg2+ concentrations of approximately 10 mM. Five moles of ATP was consumed for each mole of phosphodiester bonds cleaved. The acid-soluble products of the reaction consisted of short oligonucleotides from one to six bases in length. Only 50% of the double-stranded DNA was rendered acid soluble in a limit digest. The molecular weight of this enzyme is 3 X 10(5). The observation of these enzymes in P. aeruginosa is consistent with the possibility that recombinational pathways similar to those of Escherichia coli are operating in this organism.
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PMID:Purification and properties of two deoxyribonucleases of Pseudomonas aeruginosa. 6 Mar 31

The diastereo-enantio separation of isomeric mixtures of exametazime (HM-PAO) by liquid chromatography is described using an achiral sorbent (RP-18). A chiral eluent with the initial complex of Cu(II) and the optically active selector N,N-dimethyl-l-phenylalanine (l-DM-PhA), based on the ligand-exchange principle, has been applied. The separation is based on the presence of the immobilized binary complex Cu(l-DM-PhA)(2) and formation of mixed ternary complex. The optimal mole ratio of Cu(II):l-DM-PhA is 1:4, the pH should be between 4.1 and 4.2 and up to 0.8 mM of triethylamine is added for column presaturation with the initial complex. The elution order has been defined using isolated l-HM-PAO via l-HM-PAO L(+)tartrate and meso-HM-PAO obtained by repeated recrystallization from the isomeric mixture of HM-PAO. Complete resolution between all isomers (R(S) from 2.14 to 3.91) and partial resolution for meso(EE)/l-HM-PAO (R(S)=0.83) has been obtained. This means that the proposed chiral ligand-exchange chromatography (CLEC) can be used for determination of the isomeric purity of HM-PAO. This as an alternative method for resolution measurements with chiral columns.
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PMID:Chiral ligand-exchange chromatography for diastereo-enantio separation of exametazime. 1290 59

99M Tc (V)-d,l-HM-PAO complex is well-known radiopharmaceutical for regional cerebral blood flow imaging. The proposed modifications in exametazime, hexamethylpropyleneamine oxime (HM-PAO) (4,8-diaza-3,6,6,9-tetramethylundecane-2,10-dione bisoxime) synthesis, for reduction of intermediary reactant diiminebisoxime (DI) (4,8-diaza-3,6,6,9-tetramethylundecane-3,8-diene-2,10-dione bisoxime) concerned two reductants (NaBH(4) and KBH(4)), two solvents (ethanol and 2-propanol), and three mole ratios of reactant/reductants (1:1, 1:1.5, and 1:2). The simultaneous analysis of diastereo-enantiomeric HM-PAO content, as well as the content of starting DI, in different reduction mixtures were performed using chiral ligand-exchange chromatography (CLEC). The separation of the samples of investigated reduction mixtures, obtained in the second step of HM-PAO synthesis, has been accomplished by using an achiral sorbent (RP-18) and a chiral mobile phase (CMP) containing copper(II) complex with N,N-dimethyl-l-phenylalanine (l-DM-PhA) as initial complex for CLEC. With 12 different reduction conditions, the obtained ratios of diastereoisomers d,l-HM-PAO: meso-HM-PAO varied from 69.2:30.8 to 15.9:84.1, in comparison to the reduction in routine synthesis of HM-PAO which gives an equal mixture of diastereoisomers. The ternary mixed complexes formation recorded spectrophotometrically on addition of HM-PAO or DI to the mobile phase with binary complex Cu(l-DM-PhA)(2), due to the evidence of bathochromic shift of 46nm for lambda(max) with significant difference in absorptivity contributes to separation mechanism.
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PMID:Chiral ligand-exchange chromatography as the screening method for proposed modifications in exametazime synthesis to enhance diastereoselectivity. 1501 42