Oxygen-binding heme protein

Elstner EF, Staffer C, Heupel A (1975) Determination of superoxide free radical ion and hydrogen peroxide as products of photosynthetic oxygen reduction. Z Naturforsch 30c 53-57 Emmel T, Sand W, Konig WA, Bock E (1986) Evidence for the existence of a sulphur oxygenase in Sulfolobus brierleyi. J Gen Microbiol 132 3415-3420 Ensign SA, Hyman MR, Arp DJ (1993) In vitro activation of ammonia monooxygenase from Nitrosomonas europaea by copper. J Bacteriol 175 1971-1980 Erickson RH, Hooper AB (1972) Preliminary characterization of variant CO-binding heme protein from Nitrosomonas. Biochim Biophys Acta 275 231-244 Erickson RH, Hooper AB, Terry KR (1972) Solubilization and purification of cytochrome a, from Nitrosomonas. Biochim Biophys Acta 283 155-166 Evans MCW, Buchanan BB, Amon DI (1966) A new ferredoxin-dependent carbon reduction cycle in a photosynthetic bacterium. Proc Natl Acad Sci USA 55 928-934 Falk JE (1964) Porpyrins and metalloporphyrins. Elsevier, Amsterdam... 

Figure 8.8 P450cam secondary structural elements. Numbers above denote approximate residue numbers. Helical segments are represented by upper case letters, whereas lower case letters signify beta sheets. The heme thiolate which anchors the iron-containing and oxygen-binding heme moiety to the protein is near the start of the L helix. (Adapted from DFV Lewis and...

The solvation-desolvation of the protein surface might be considered as a means of storing or spending energy in a way that can be shifted to other parts of the molecule, such as the oxygen-binding heme groups, when molecular transitions occur. 

The precise structural identities of the high-valent oxo-iron states of heme systems are also of interest. Recent work by Mayer [101] indicates that the Fe =0 bond of an oxo iron (IV) complex is 0.1 A longer than expected in comparison with other metal oxo complexes. The oxygen-binding respiratory proteins hemoglobin and myoglobin will each form a relatively stable derivative... 

The most conspicuous use of iron in biological systems is in our blood, where the erythrocytes are filled with the oxygen-binding protein hemoglobin. The red color of blood is due to the iron atom bound to the heme group in hemoglobin. Similar heme-bound iron atoms are present in a number of proteins involved in electron-transfer reactions, notably cytochromes. A chemically more sophisticated use of iron is found in an enzyme, ribo nucleotide reductase, that catalyzes the conversion of ribonucleotides to deoxyribonucleotides, an important step in the synthesis of the building blocks of DNA. 

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