Results from the protein test experiment
This photograph shows some of the results from the followup tests from the enzyme investigations.
Biuret reagent - on the right hand side - is a light blue colour. In the presence of (soluble) protein it gradually turns a violet colour.
The enzyme pepsin and its substrate in the investigation egg white each turn biuret reagent violet as they are both proteins.
Similarly, the enzymes lipase and amylase are positive, as is gelatin, a soluble protein.