The Copper Complexes of Amino-acids, Peptides and Peptones

That proteins and their constituents combine with heavy met’als to form “complexes” has been known for some time. Among these copper has received the most attention and considerable work has been done on the copper complexes of amino-acids; t’hey have been isolated,2 analyzed and studied by chemical and physical methods. On the other hand the complexes of peptides and peptones have received only a superficial and qualitative study. This is not due to the unimportance of peptide copper salts, for the behavior of peptide and peptone copper salts on treatment with an excess of alkali has been and is yet the most reliable test known for protein-like substances. The real reason for this lack of investigation is, without doubt, due first to the difficulty of obtaining peptides and peptones pure, and second to the fact that the copper salts of these substances are not easily crystallized. It is our belief that a quantitative study of these copper salts3 will throw some light on the constit,ution of proteins and it is therefore our intention to continue from time to time our efforts in this field. In a previous preliminary communication4 one of us showed a