Myoglobin, function properties

The myoflbers of muscle are not homogenous but can be categorized into red and white on the basis of ATPase activity ( ). Not only the functional properties but also the composition of the two fiber types varies widely. Red fibers, for example, have considerably more myoglobin and lipid than do white type fibers. 

In addition to activities ordinarily ascribed to them, peroxidase and catalase possess properties as oxygen transferases and mixed function oxidases. They may exist in functionally active ferrous forms which have, like hemc lobin and myoglobin, the property of combining with molecular oxygen. This oxygen may be transferred to substrate, or be reduced in steps. For purposes of the present review, mechanisms that have been proposed for peroxidatic and catalatic oxidations will be summarized and followed by discussion of dihydroxyfumaric acid oxidase, tryptophan oxidase, and indolyl-acetic oxidase and related oxidases, and indole oxidase. All of these have properties in common with peroxidase and catalase. 

Metals at the active sites of metalloproteins display special properties and are generally impressively efficient in their functional roles. The metal or metals are said to be poised for catalytic action or in an entatic state, an expression first used by Vallee and Williams in their seminal paper of 1968 (2). The fine tuning or control of the peptide in many cases results in previously unobserved aspects of the coordination chemistry of the metal in question. There are many examples, almost as many as there are metalloproteins, from (in the case of Fe) the five-coordinate high-spin Fe(II) in myoglobin and hemoglobin... 

---