Dr. Al Claiborne
Professor of Biochemistry 

B.A., Vanderbilt University, 1974 
Ph.D. (Biochemistry), Duke University, 1979 

Telephone: (336) 716-3914 
Email: alc@invader.bgsm.wfu.edu

Gram-positive bacteria such as the streptococci present an intriguing system for investigating the structural, functional, and genetic aspects of oxygen metabolism. These facultative anaerobes lack the ability to synthesize heme and therefore do not have either catalase or the respiratory cytochromes found in other bacteria such as Escherichia coli. In place of these hemeproteins, streptococci have developed an unusual array of flavin-linked enzymatic responses to the presence of oxygen and its metabolites; these include the NADH peroxidase and NADH oxidase, which have been studied intensively in our laboratory. The combined application of molecular cloning and sequencing approaches with X-ray crystallography and functional analyses has allowed us to demonstrate that these proteins represent a new class of peroxide reductases within the flavoprotein disulfide reductase family. A major distinction between the peroxide and disulfide reductase classes lies in the unique cysteine-sulfenic acid (Cys-SOH) redox center identified in the peroxidase and oxidase, in contrast to the redox-active disulfides (Cys-SS-Cys) found in the disulfide reductases. My laboratory is currently applying technologies spanning the range from recombinant protein expression and site-directed mutagenesis to rapid reaction kinetics and molecular graphics in the study of the peroxidase and oxidase. Ongoing high-resolution NMR and X-ray crystallographic approaches are being applied as well, toward our ultimate goal of understanding the structural and mechanistic adaptations which allow these flavoproteins to catalyze reactions in oxygen metabolism normally requiring either direct heme enzyme involvement or heme-mediated electron transport.