Nucleases essential functions

Nuclease-(1-126) is inactive and appears to be disordered as judged by measurements of optical rotation, circular dichroism, and intrinsic viscosity 80). Nuclease-(127-149) is also inactive and does not bind to nuclease-(1-126) (80). Thus, the cleavage of the peptide bond between residues 126 and 127 destroys the functional structure of nuclease in contrast to the cleavage of bonds in the region of residues 48-50, which leaves the structure of nuclease essentially unchanged. 

In addition to common nucleases listed in Table 12.9, cells contain many distinct nucleases, which perform essential functions (Deutscher, 1993). For example, RNases are involved in ... 

Metal ions released from metal implants by osteoclastic bio-corrosion are distributed through- out the body and are eventually taken up by dendritic cells, the most potent anti-gen-presenting cells [14, 15, 18]. Besides changing phenotypic and functional properties of dendritic cells [18], metal ions complex with cellular proteins and peptides. In case of titanium, the ions form complexes with phosphorus-containing proteins and peptides (usually signaling molecules), nucleotides (DNA in the nuclease and RNA in the cytoplasm) and lipids (phospholipids of the cellular membranes) [15]. The new antigenic metal-peptides are presented by dendritic cells to specific T-lymphocytes that react and are activated [15]. The dendritic cells and activated T-lymphocytes accumulate in tissues with high metal concentrations, usually close to the metal implant, and form inflammatory reactions [7] that include secretion of inflammatory cytokines, such as TNF-a, TGF-b, interleukin-6 and interleukin-lb [19]. Most important is secretion of RANK-L by the activated T-lymphocytes, an essential factor for maturation, survival and function of osteoclasts [19]. 

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