Cobalt ions bacterial

As mentioned above, certain metal ions may be necessary for activity or stability. Thus calcium is needed for bacterial a-amylase. Magnesium or cobalt is needed with glucose isomerase. Calcium stabilises the starch-liquifying bacterial a-amylases but inactivates the glucose isomerase that may be used subsequently. Many enzymes contain an additional non-... 

The crystal structure of the mouse R2 RR has also been solved but it contained only one iron ion, maybe because in this enzyme the iron/radical site is more exposed to the solvent [72]. A recent report on the crystal structure of this mamma-Han R2 with a dinuclear cobalt center replacing iron foimd a different orientation for one of the glutamate Hgands when compared with the bacterial enzyme [73]. This could explain the increased labiHty of one of the iron centers. Because the substrate-binding site in R1 and the radical-generating site in R2 are far apart a... 

For each of the aforementioned cell samples, there were two EMS components corresponding to two chemical forms of high-spin Co". (The presence of the third component with the parameters typical for high-spin nucleogenic iron(lll), stabilized after nuclear decay of the parent Co + ion, is evidently a result of aftereffects of the Co Fe nuclear transformation, as Co " is not expected to appear in such systems.) The presence of at least two major cobaltous forms (with different 5 and A q values, see Table 17.1) revealed in the spectra of cells maybe related to the availability of different functional groups (also with possibly different donor atoms) as ligands at the bacterial cell surface (see, for example. Refs 31,32 and references therein). 

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