Delta-1-pyrroline-5-carboxylate

Delta-1-pyrroline-5-carboxylate (also known as P5C or 1-pyrroline-5-carboxylate) is a metabolite involved in several important biochemical pathways in the human body. It is an intermediate in both the proline and arginine biosynthesis pathways, and plays a crucial role in the cellular response to osmotic stress.

Structure and Properties[edit | edit source]

Delta-1-pyrroline-5-carboxylate is a cyclic amino acid derivative, with a five-membered ring structure. It has a carboxylate group at the 5-position, and a double bond between the 1- and 2-positions. This gives it a degree of aromaticity, which can influence its reactivity and interactions with other molecules.

Biosynthesis[edit | edit source]

P5C is synthesized from glutamate in a two-step process. First, glutamate is reduced to glutamate semialdehyde by the enzyme glutamate 5-kinase. This is then spontaneously converted to P5C.

In the reverse direction, P5C can be converted back to glutamate by the enzyme P5C dehydrogenase, in a reaction that also produces NADH.

Role in Proline and Arginine Biosynthesis[edit | edit source]

P5C is a key intermediate in the biosynthesis of the amino acids proline and arginine. In the proline biosynthesis pathway, P5C is reduced to proline by the enzyme P5C reductase, using NADH as a cofactor.

In the arginine biosynthesis pathway, P5C is first converted to ornithine by the enzyme ornithine aminotransferase. Ornithine is then converted to arginine via a series of reactions known as the urea cycle.

Role in Osmotic Stress Response[edit | edit source]

Under conditions of osmotic stress, cells can accumulate high levels of P5C, which can be converted to proline. Proline acts as a compatible solute, helping to maintain cell volume and protect cellular structures.