title: T4-phage deoxycytidylate deaminase is a metalloprotein containing two zinc atoms per subunit.
abstract: Deoxycytidylate (dCMP) deaminase, a hexameric allosteric enzyme induced on infection of Escherichia coli by bacteriophage T4, was shown to contain two atoms of zinc per subunit by atomic absorption spectroscopy. One zinc appears to be involved in catalysis, as described for adenosine deaminase (Sharaff, A. J., Wilson, D. K., Chang, Z., and Quiocho, F. A. (1992) J. Mol. Biol. 226, 917-921) and cytidine deaminase (Yang, C., Carlow, D., Wolfenden, R., and Short, S. A. (1992) Biochemistry 31, 4168-4174). This thesis is supported by the finding that the enzyme loses about 80% of its activity in the presence of o-phenanthroline. It has also been found that zinc is released when the enzyme is denatured in the presence of the metallochromic indicator, 4-(2-pyridylazo)resorcinol. Renaturation of the deaminase to an active form occurred in the presence but not in the absence of zinc. The second atom of zinc is proposed to be located in a region of T4-dCMP deaminase that resembles a zinc finger. This region, which has the sequence His-X3-Cys-X14-His-X3-His, would represent a zinc-binding motif that has not been described previously.
authors.affiliation: Wadsworth Center for Laboratories and Research, New York State Department of Health and Department of Biomedical Sciences, School of Public Health, State University of New York, Albany 12201-0509.
authors.forename: J T
authors.initials: JT
authors.lastname: Moore
authors.forename: R E
authors.initials: RE
authors.lastname: Silversmith
authors.forename: G F
authors.initials: GF
authors.lastname: Maley
authors.forename: F
authors.initials: F
authors.lastname: Maley
mesh_terms: D000595:Amino Acid Sequence; D001665:Binding Sites; D003844:DCMP Deaminase / Q000037:antagonists & inhibitors / Q000737:chemistry* / Q000378:metabolism; D008667:Metalloproteins / Q000737:chemistry; D008969:Molecular Sequence Data; D010618:Phenanthrolines / Q000494:pharmacology; D011489:Protein Denaturation; D013054:Spectrophotometry, Atomic; D013604:T-Phages / Q000201:enzymology*; D014764:Viral Proteins / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000378:metabolism; D015032:Zinc / Q000032:analysis*; D016335:Zinc Fingers
chemical_list: D008667:Metalloproteins; D010618:Phenanthrolines; D014764:Viral Proteins; D003844:DCMP Deaminase; D015032:Zinc; C025205:1,10-phenanthroline