Protein kinase C substrate is a substrate of Protein kinase C, can be used to detect protein. Protein kinase C is a key regulatory element in signal transduction and exerts its effects by catalysing specific substrate phosphorylation.

C-Phycocyanin is a water-soluble protein pigment that is also used as a nutrient supplement for human beings.

2,2'-Dipyridyl disulfide is a useful reagent for determination of sulfhydryl groups, preparation of amino acid active esters and the thio esters of phosphoric acid.