Carboxyl groups have an electronegative oxygen atom double bonded to a carbon atom. This carbon-oxygen bond is very polar and the fact that its a double bond increases the polarity of the bond.
PEA agar, also referred to as Phenylethyl Alcohol Agar is a medium  used by microbiologists to grow microorganisms. The ingredient that  supplies nitrogen is casein. Making the world better, one answer at a time.
Download Dr. Jonejaâs guide to growing DAO rich sprouts here: Pea seedlings as a supplement. As I outline in my first book, a diet rich in vitamin B6, magnesium, copper and other nutrients is necessary in order for our body to produce the histamine-lowering enzyme DAO (diamine oxidase).