Amino acid function, VIII

The functions of the above three classes of proteins are directly related to the protein-bound copper ions. In those cases where functions have been unequivocally established, they are either electron storage and transfer or redox catalysis. Representative proteins from each of the above-mentioned classes have been purified directly from their natural sources and extensively characterized both structurally and biophysically. In addition, there are well-established protocols for their expression and purification from different heterologous systems. [Factor VIII is a special case for which blue copper binding has not been experimentally demonstrated, although at least two such sites can be identified in its amino acid sequence (Section VIII).]... 

Table VIII shows the 12 amino acids which have remained totally invariant throughout the 67 known eukaryotes and the five photosynthetic and respiratory bacterial cytochromes of Table VII. It is a remarkably long list considering that it may represent as much as three eons of independent development, and it must provide evidence for an irreducible minimum necessary for a functioning cytochrome molecule. The list could be enlarged by including obvious functional equivalents such as tyrosine-phenylalanine at position 46, but this shorter list gains in impressiveness by its total constancy.

VIII. Further Evidence for Possible Functional hnphcations of Siahdases IX. /n silica Analysis of Siahdase Gene Expression Patterns Amino Acid Sequence Variants in Human Siahdases Siahdases in Teleosts... 

Amino acid oxidase oxidatively deaminates the amino acid at the left (one of many) the enzyme specifically catalyzes this particular reaction as described extensively in Chapt. VIII-7. Another possible reaction, decarboxylation, does not occur. The catalysis of CO2 loss requires a different enzyme, and a third reaction, transamination, requires a third enzyme assisting in the exchange of functional groups (the keto group of oxaloacetic acid with the amino group). Obviously each of the three enzymes possesses a characteristic reaction specificity this is true for all enzymes. 

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