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This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Rights and Permissions Citing Articles Citing Articles via HighWire Citing Articles via CrossRef Citing Articles via Google Scholar Google Scholar Articles by Zerez, C. R. Articles by Tanaka, K. R. Search for Related Content PubMed PubMed Citation Articles by Zerez, C. R. Articles by Tanaka, K. R. Social Bookmarking                   What's this?  Previous Article  |  Table of Contents  |  Next Article  Partial purification and properties of nicotinamide adenine dinucleotide synthetase from human erythrocytes: evidence that enzyme activity is a sensitive indicator of lead exposure CR Zerez, MD Wong and KR Tanaka Department of Medicine, Harbor-UCLA Medical Center, Torrance 90502. We have examined properties of nicotinamide adenine dinucleotide (NAD) synthetase from human erythrocytes. The enzyme was found to be cold labile and extremely unstable in crude hemolysate, with complete loss of activity occurring after 24 hours at 4 degrees C. However, maintenance of crude hemolysate at 20 to 25 degrees C in the presence of EDTA and KCl increased NAD synthetase stability substantially (half- life = 10 days). Using these conditions, NAD synthetase was purified 3,100-fold with a 29% yield using DEAE-cellulose column chromatography, ammonium sulfate fractionation, and dialysis. The apparent Michaelis- Menten constants for nicotinic acid adenine dinucleotide (NAAD), adenosine triphosphate, Mg2+, glutamine, and K+ were 0.108, 0.154, 1.36, 2.17, and 8.32 mmol/L, respectively. The pH optimum ranged between 6.8 and 7.4, and the molecular weight was estimated to be 483 +/- 5 Kd. The enzyme was markedly inhibited by Pb2+ and Zn2+, with concentrations necessary for 50% inhibition of activity of 1.3 and 2.0 mumol/L, respectively. The incubation of intact red blood cells with lead followed by rigorous washing to remove lead abolished nearly all NAD synthetase activity. In contrast, glucose-6-phosphate dehydrogenase activity, which is not sensitive to lead, was unaffected, whereas pyrimidine 5'-nucleotidase activity, which is sensitive to lead, was decreased 30% to 50% under these conditions. More importantly, patients with lead overburden (34 to 72 micrograms Pb2+/dL blood) all had markedly decreased NAD synthetase activity. These data together with other results suggest that erythrocyte NAD synthetase activity is a sensitive indicator of lead exposure in humans. Volume 75, Issue 7, pp. 1576-1582, 04/01/1990 Copyright © 1990 by The American Society of Hematology CiteULike    Connotea    Del.icio.us    Digg    Reddit    Technorati    What's this? This article has been cited by other articles: N. Hara, K. Yamada, M. Terashima, H. Osago, M. Shimoyama, and M. Tsuchiya Molecular Identification of Human Glutamine- and Ammonia-dependent NAD Synthetases. CARBON-NITROGEN HYDROLASE DOMAIN CONFERS GLUTAMINE DEPENDENCY J. Biol. Chem., March 21, 2003; 278(13): 10914 - 10921. [Abstract] [Full Text] [PDF]

	Copyright © 1990 by American Society of Hematology         Online ISSN: 1528-0020