LIFE SCIENCE

Detailed explanation-1: -Proline and hydroxyproline contains an -imino group and, therefore, they are -imino acids (Fig. 1). However, because proline is a substrate for protein synthesis like a-AA and hydroxyproline is its post-translational metabolite, they are loosely referred to as AA in biochemistry.

Detailed explanation-2: -Proline. Proline contains a secondary amine group, called an imine, instead of a primary amine group. For this reason, proline is called an imino acid.

Detailed explanation-3: -Hydroxyproline is produced by hydroxylation of the amino acid proline by the enzyme prolyl hydroxylase following protein synthesis (as a post-translational modification). The enzyme catalyzed reaction takes place in the lumen of the endoplasmic reticulum.

Detailed explanation-4: -The only proteinogenic amino acid of this type is proline, although the related non-proteinogenic amino acids hydroxyproline and pipecolic acid have often been included in studies of this class of compounds.

Detailed explanation-5: -Hydroxyproline is a neutral heterocyclic protein amino acid. It is found in collagen and as such it is common in many gelatin products. Hydroxyproline is mostly used as a diagnostic marker of bone turnover and liver fibrosis.