Brooks B W, Young N M, Watson D C, Robertson R H, Sugden E A, Nielsen K H, Becker S A
Agriculture Canada, Animal Diseases Research Institute, Nepean, Ontario, Canada.
J Clin Microbiol. 1991 Aug;29(8):1652-8. doi: 10.1128/jcm.29.8.1652-1658.1991.
By using a combination of agarose and polyacrylamide gel electrophoresis, Mycobacterium paratuberculosis antigen D was resolved from a crude sonicated preparation of the organism and characterized as a component with a molecular mass of approximately 400,000 Da. While this component was composed mainly of protein, with unusually high proportions of glutamic acid and leucine, it was resistant to digestion with a number of proteolytic enzymes. Structural detail revealed by electron microscopy, amino acid sequence data, and the demonstration of a Soret band in its absorption spectrum indicated that antigen D was similar to an Escherichia coli bacterioferritin.