Proline is one of the twenty amino acids that are used by living organisms as a building block of proteins. Technically, proline is an imino acid, as it contains no amino group.
In proteins, proline can act as a structural disruptor for α helices, and as a turning point in β sheets. Multiple prolines in a row can create a proline helix.
... he was admitted
to the Augustinian convent of Mount Saint Agnes
near Zwolle where his brother John had been before
him and had risen to the dignity of prior. Thomas ...