Metalloproteins

Publisher Website
Google Scholar
Abstract
The present status of our knowledge of metalloenzymes gives cause for both joy and sorrow. The number and diversity of enzymatic reactions which are dependent upon metalloproteins could scarcely have been envisioned by the pioneers who opened up the field through studies on the nonheme oxygen-carrying proteins. On the other hand, it is discouraging that we still do not know precisely the nature of the organic-chemical bonding about the central metal ion. At this juncture it seems that the first complete structure of a metalloprotein will be provided through application of one of two methods, both of which have experienced substantial technological advances in recent years-amino acid sequence analysis and crystallography. The determination of the amino acid composition of a pure protein is now not vastly more difficult than the establishment of the empirical formula of an organic compound, and the fixing of the sequence of the amino acid residues is similarly a relatively straightforward exercise in organic structural characterization. In the case of crystallography, the introduction of computers and other mechanical devices has eliminated much of the tedious work which hitherto detracted from the elegance and effectiveness of this technique. Applied to "simple" metalloproteins such as the ferredoxins, in which the equivalent weight based on metal content is not too large, these approaches should afford rewarding results. Substantial progress in this direction has already been made with carbonic anhydrase (203) and with carboxypeptidase (202).