The product is a recombinant, biosynthetic, fast-acting insulin analogue. It has a single amino acid substitution at position B28 where proline is replaced with aspartic acid. This substitution decreases its propensity to form hexamers. The product is produced in a genetically modified strain of Saccharomyces cerevisiae and harvested from a bioreactor. Aspart https://www.creativebiomart.net/therapeutic-proteins/p/124/fast-acting-insulin-analogue-has-a-single-amino-acid-substitution-at-position-b28-where-proline-is-replaced-with-aspartic-acid/