The secreted Mycobacterium bovis BCG antigen 85 complex, which is known to bind to human fibronectin, consists of three closely related cross-reacting antigens. Amino-terminal sequence analysis of the purified proteins showed distinct differences. Data are presented to show that the three components are produced by individual cells, which indicates that three separate genes are involved. INFECT. IMMUN. on August 5, 2020 by guest http://iai.asm.org/ Downloaded from

Amyloid fibrils were extracted from deposits in joint tissue of heavy breed layers with spontaneous amyloid arthropathy and characterized as being of the AA-type. Amino acid sequencing revealed a pattern quite similar to duck AA. Acute phase sera of chicken experimentally injected with Enterococcus faecalis showed a SAA-protein like band cross reacting with anti-chicken AA in immunoblot.

An amyloid fibril protein AR has been further characterized as to amino acid sequence of the first 45 N‐terminal residues. There are clear homologies with light chain‐variable regions, particularly with λ light chains and mostly with the VλII subgroup. However, there is as much as a 55% difference from the Vλ.II subgroup and even greater differences from other subgroups. This is much more than the variation known to occur within a given light chain‐variable subgroup and also a greater difference than those known to occur between the existing subgroups. For this reason protein AR appears to be the prototype for a new variable subgroup of λ chains. In agreement with the National Biomedical Research Foundation, this new subgroup is termed VλV.

An Fh fragment corresponding to the hinge region of IgG3 has been isolated by J single α‐chymotrypsin treatment of whole IgG3 Various combinations of two enzymes have also been used, but with somewhat lower yield and less purity The isolated Fh fragment has features similar to those of the bound hinge region in the intact IgG3 and its F(ab')2 and Fch fragments. The Fh fragment has a char acteristically high content of cystine and proline and seems to lack aromatic amino acids

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