D-Aminolevulinic acid

D-Aminolevulinic acid (dALA or δ-ALA or 5-aminolevulinic acid) is the first compound in the porphyrin synthesis pathway, the pathway that leads to hemoglobin in mammals.

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In non-photosynthetic eukaryotes such as animals, insects, fungi, and protozoa as well as the α-proteobacteria group of bacteria it is produced by the enzyme ALA synthase, from glycine and succinyl CoA. This reaction is known as the Shemin pathway.

In plants, algae, bacteria (except for the α-proteobacteria group) and archaea it is produced from glutamic acid via glutamyl-tRNA and glutamate-1-semialdehyde. The enzymes involved in this pathway are glutamyl-tRNA synthetase, glutamyl-tRNA reductase and glutamate-1-semialdehyde aminotransferase. This pathway is known as the C5 or Beale pathway.^[1][2]

Clinical significance

It elicits synthesis and accumulation of fluorescent porphyrins (protoporphyrin IX) in epithelia and neoplastic tissues, among them malignant gliomas. It is used to visualise tumorous tissue in neurosurgical procedures. Studies ^[3] have shown that the intraoperative use of this guiding method may reduce the tumour residual volume and prolong progression-free survival in patients suffering from this disease.

dALA is also a photosensitizer for photodynamic therapy.

References

1. ^ Beale, Samuel I. (1990) Biosynthesis of the tetrapyrrole pigment precursor, d-aminolevulinic acid, from glutamate. Plant Physiology, 93(4), 1273-1279
2. ^ Willows R.D. (2004) Chlorophylls In: Encylopaedia of Plant and Crop Science. pp 258-262, Ed: Robert M. Goodman. Marcel Dekker Inc, ISBN 0-8247-4268-0
3. ^ Stummer W, Pichlmeier U, Meinel T, Wiestler OD, Zanella F, Reulen HJ (2006). "Fluorescence-guided surgery with 5-aminolevulinic acid for resection of malignant glioma: a randomised controlled multicentre phase III trial". Lancet Oncol. 7 (5): 392-401. doi:10.1016/S1470-2045(06)70665-9. PMID 16648043.

See also

• Porphyrin