Michael Behe — American Scientist

Michael J. Behe is an American biochemist, author, and intelligent design advocate. He serves as professor of biochemistry at Lehigh University in Pennsylvania and as a senior fellow of the Discovery Institute's Center for Science and Culture. Behe is best known for his argument for irreducible complexity, which argues that some biochemical structures are too complex to be explained by known evolutionary mechanisms and are therefore probably the result of intelligent design. Behe has testified in several court cases related to intelligent design, including the court case Kitzmiller v. Dover Area School District that resulted in a ruling that intelligent design was religious in nature... (wikipedia)

As can be seen even by this limited number of examples proteins carry out amazingly diverse functions.
Proteins are the machinery of living tissue that builds the structures and carries out the chemical reactions necessary for life.
It is often said that science must avoid any conclusions which smack of the supernatural.
Thus it seemed to Haeckel that such simple life could easily be produced from inanimate material.
In Darwin's time all of biology was a black box: not only the cell, or the eye, or digestion, or immunity, but every biological structure and function because, ultimately, no one could explain how biological processes occurred.