Wiktionary
nonprotein
a. Having a source other than protein. n. That which is not a protein.
Usage examples of "nonprotein".
For example, porphyrin complexed with iron or magnesium is the nonprotein part of hemoglobin and chlorophyll.
In addition, a number of hormones turned out to be nonprotein in structure and, as far as we know, all enzymes are proteins.
The molecule of rhodopsin is made up of two parts: a protein, opsin, and a nonprotein portion, very similar in structure to vitamin A, which is retinene.