Among the many important contributions of Kossel was his study of the chemistry of the cell and cell-nucleus. Kossel correctly concluded that the function of nuclein is neither to act as a storage substance nor to furnish energy for muscular contraction; rather, it must be associated with the formation of fresh tissue, i.e. the production of proteins.

In 1910 Kossel was awarded the Nobel Prize in Physiology or Medicine "for his research in cell biology, the chemical composition of the cell nucleus, and for his work in isolating and describing nucleic acids."

See No. 702.

Kossel forecast the polypeptide nature of the protein molecule.