Biocytin

What it isBiotin bound to lysine — the form in which biotin functions on, and is recycled from, its carboxylase enzymes.

Why it mattersBiotinidase releases biotin from biocytin; without that recycling, dietary biotin cannot keep up.

What it changesBiotinidase deficiency, a newborn-screening target, is treated with pharmacologic biotin for life.