Keto acids that are derivatives of 4-oxopentanoic acids (levulinic acid).

"Semicarbazones are compounds formed when semicarbazide reacts with an aldehyde or ketone, creating a bond that includes a hydrogen bond donor and acceptor, which can be useful in the identification and analysis of carbonyl groups in organic chemistry and medicinal research."

A compound produced from succinyl-CoA and GLYCINE as an intermediate in heme synthesis. It is used as a PHOTOCHEMOTHERAPY for actinic KERATOSIS.

The study of the energy of electrons ejected from matter by the photoelectric effect, i.e., as a direct result of absorption of energy from electromagnetic radiation. As the energies of the electrons are characteristic of a specific element, the measurement of the energy of these electrons is a technique used to determine the chemical composition of surfaces.

An enzyme that catalyzes the formation of porphobilinogen from two molecules of 5-aminolevulinic acid. EC 4.2.1.24.