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Class Ic ribonucleotide reductase (RNR) from Chlamydia trachomatis (C. tm.) lacks the tyrosyl radical and uses a Mn(IV)-Fe(III) cluster for cysteinyl radical initiation in the large subunit. Here we investigated and compared the metal content and specific activity of the C. tm. wild-type R2 protein and its F127Y mutant, as well as the native mouse R2 protein and its Y177F mutant, all produced as recombinant proteins in Escherichia coli. Our results indicate that the affinity of the RNR R2 proteins for binding metals is determined by the nature of one specific residue in the vicinity of the dimetal site, namely the one that carries the tyrosyl radical in class Ia and Ib R2 proteins. In mouse R2, this tyrosyl residue is crucial for the activity of the enzyme, but in C. tm., the corresponding phenylalanine plays no obvious role in activation or catalysis. However, for the C. tm. wild-type R2 protein to bind Mn and gain high specific activity, there seems to be a strong preference for F over Y at this position. In studies of mouse RNR, we find that the native R2 protein does not bind Mn whereas its Y177F mutant incorporates a significant amount of Mn and exhibits 1.4% of native mouse RNR activity. The observation suggests that a manganese-iron cofactor is associated with the weak activity in this protein.

The rates of reduction of the diferric/radical center in mouse ribonucleotide reductase protein R2 were studied by light absorption and EPR in the native protein and in three point mutants of conserved residues involved in the proposed radical transfer pathway (D266A, W103Y) or in the unstructured C terminal domain (Y370W). The pseudo-first order rate constants for chemical reduction of the tyrosyl radical and diferric center by hydroxyurea, sodium dithionite or the dihydro form of flavin adenine dinucleotide, were comparable with or higher (particularly D266A, by dithionite) than in native R2. Molecular modeling of the D266A mutant showed that the iron/radical site should be more accessible for external reductants in the mutant than in native R2. The results indicate that no specific pathway is required for the reduction. The dihydro form of flavin adenine dinucleotide was found to be a very efficient reductant in the studied proteins compared to dithionite alone. The EPR spectra of the mixed-valent Fe(II)Fe(III) sites formed by chemical reduction in the D266A and W103Y mutants were clearly different from the spectrum observed in the native protein, indicating that the structure of the diferric site was affected by the mutations, as also suggested by the modeling study. No difference was observed between the mixed-valent EPR spectra generated by chemical reduction in Y370W mutant and native mouse R2 protein

The aim was to see how burn victims experience their situation and if they feel suffering. Then it is discussed against different perspectives of suffering. The problems were ?How does a burn victim experience their situation??, ?Does a burn victim suffer?? and ? How does the attitude inflect the suffering?? To find the answers, the authors made a literature review in which already published interviews from ordinary papers were used. In the result, the authors used the individual?s own words. The word shows that the persons suffer in many ways. For example, the look changes, the pain is constant and the people feel insecure in their life. The authors find out that a burn is a traumatic experience and it is a dramatic change in the individual?s life. An individual need to talk about the accident and the situation. It is important that the burn victim feel support so they easier can get on with their life. Sammanfattning Syftet var att ta reda på hur brännskadade människor upplever sin situation och om det förekommer något lidande. Detta diskuteras utifrån olika lidandeperspektiv. Problemformuleringarna var ?Hur upplever brännskadade individer sin situation??, ?Upplever en brännskadad individ ett lidande?? och ?Hur påverkar människans inställning lidandet??. För att belysa detta har författarna gjort en litteraturstudie där publicerade intervjuer, från vanlig dagspress, har använts. I resultatet används citat från de drabbade. Citaten visar att brännskadade individer lider på flera olika sätt. Exempel är att utseendet förändras, att alltid ha olidliga smärtor samt att individerna känner en otrygghet i sitt liv. Författarna har kommit fram till att en brännskada är en traumatisk upplevelse som förändrar individens liv radikalt. En individ behöver få prata igenom sin situation. Det är även viktigt att den drabbade får stöd för att kunna gå vidare i sitt liv.