Biological Functions of Iron-Containing Proteins

This may explain why this family of bacteria are foimd in dairy products, where the presence of lactoferriin makes iron availabihty problematic. Class II RNRs are also found in some archaebacteria. 

FIGURE 13.3 The three classes of RNRs utilize their metallo-cofactors to generate an active-site thiyl radical (S ). The diferric-tyrosyl radical in class 1 enzymes is on the R2 subunit, at best 35 A from the thiyl radical (on subunit Rl). (Fmm Stubbe et al, 2001.) 

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