Fig. 5

![Fig. 5: Cofactor balance analysis showing tetrahydrobiopterin (BH4) or related cofactor levels in the 5-HTP-producing E. coli strains. Adequate cofactor supply is essential for tryptophan hydroxylase activity and efficient 5-HTP biosynthesis.](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9509612/bin/12934_2022_1920_Fig5_HTML.jpg)

> Source: Zhen Zhang et al. "Metabolic engineering of Escherichia coli for efficient production of L-5-hydrox." *Microbial cell factories*, 2022. PMID: [36153615](https://pubmed.ncbi.nlm.nih.gov/36153615/)

<figure>
  <img src="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9509612/bin/12934_2022_1920_Fig5_HTML.jpg" alt="Cofactor balance analysis showing tetrahydrobiopterin (BH4) or related cofactor levels in the 5-HTP-producing E. coli strains. Adequate cofactor supply is essential for tryptophan hydroxylase activity and efficient 5-HTP biosynthesis." />
  <figcaption>Fig. 5. Cofactor balance analysis showing tetrahydrobiopterin (BH4) or related cofactor levels in the 5-HTP-producing E. coli strains. Adequate cofactor supply is essential for tryptophan hydroxylase activity and efficient 5-HTP biosynthesis.<br>  Source: Zhen Zhang et al. "Metabolic engineering of Escherichia coli for efficient production of L-5-hydrox." <em>Microbial cell factories</em>, 2022. PMID: <a href="https://pubmed.ncbi.nlm.nih.gov/36153615/">36153615</a></figcaption>
</figure>