Citation, DOI, disclosures and article data
At the time the article was created Daniel J Bell had no recorded disclosures.View Daniel J Bell's current disclosures
Amino acids are the monomeric building blocks of proteins. Amino acids concatenate into chains, which are arbitrarily divided into peptides, polypeptides, or proteins according to chain length. Generally, chains of 10 or fewer amino acids are deemed to be peptides, chain length from 10-100 are polypeptides, and greater than ~100 amino acids are called proteins.
All amino acids (except proline) consist of a carboxyl (-COOH) group and an amino (-NH2) group, with varying side chains.
Proline is chemically strictly an imino acid, which has an imino (>C=NH) group, instead of an amino group, although for biological usage it is counted as an amino acid.
List of amino acids
Essential vs non-essential
Essential amino acids cannot be synthesized by the cells, and therefore must be obtained from the diet.
Conversely the non-essential amino acids can be made by the body and therefore are not mandatory constituents of a balanced diet.
The list of amino acids has the full name of the amino acid and in parentheses the standard three letter code and single letter code.
Essential amino acids
- valine (Val, V)
- leucine (Leu, L)
- isoleucine (Ile, I)
- threonine (Thr, T)
- methionine (Met, M)
- phenylalanine (Phe, F)
- tryptophan (Trp, W)
- lysine (Lys, K)
- histidine (His, H)
Non-essential amino acids
- glycine (Gly, G)
- alanine (Ala, A)
- serine (Ser, S)
- cysteine (Cys, C)
- tyrosine (Tyr, Y)
- aspartic acid (Asp, D)
- asparagine (Asn, N)
- glutamine (Gln, Q)
- glutamic acid (Glu, E)
- proline (Pro, P)
- arginine (Arg, R)
- selenocysteine (Sec, U)
Radiolabeled amino acids
Some amino acids can be labeled with radioactive isotopes for use in nuclear medicine 3,4. Methionine, for example, labeled with carbon-11 can be used in the study of tumors of the central nervous system 5-7. One more example: 18F-DOPA, an intermediate amino acid in the biosynthetic pathway of dopamine, labeled with fluorine-18 is used in the study of Parkinson disease 8-10.
- 1. Kim E. Barrett, Susan M. Barman, Scott Boitano, Heddwen L. Brooks. Ganong's Review of Medical Physiology. (2015) ISBN: 9781259255380
- 2. William Alexander Newman Dorland. Dorland's Illustrated Medical Dictionary. (2018) ISBN: 9781416023647
- 3. Jager PL, Vaalburg W, Pruim J, de Vries EG, Langen KJ, Piers DA. Radiolabeled amino acids: basic aspects and clinical applications in oncology. (2001) Journal of nuclear medicine : official publication, Society of Nuclear Medicine. 42 (3): 432-45. Pubmed
- 4. Huang C, McConathy J. Radiolabeled amino acids for oncologic imaging. (2013) Journal of nuclear medicine : official publication, Society of Nuclear Medicine. 54 (7): 1007-10. doi:10.2967/jnumed.112.113100 - Pubmed
- 5. Ribom D, Smits A. Baseline 11C-methionine PET reflects the natural course of grade 2 oligodendrogliomas. (2005) Neurological research. 27 (5): 516-21. doi:10.1179/174313213X13789811969265 - Pubmed
- 6. Ribom D, Schoenmaekers M, Engler H, Smits A. Evaluation of 11C-methionine PET as a surrogate endpoint after treatment of grade 2 gliomas. (2005) Journal of neuro-oncology. 71 (3): 325-32. doi:10.1007/s11060-004-2031-5 - Pubmed
- 7. Tang BN, Sadeghi N, Branle F, De Witte O, Wikler D, Goldman S. Semi-quantification of methionine uptake and flair signal for the evaluation of chemotherapy in low-grade oligodendroglioma. (2005) Journal of neuro-oncology. 71 (2): 161-8. doi:10.1007/s11060-004-9654-4 - Pubmed
- 8. Fischman AJ. Role of [18F]-dopa-PET imaging in assessing movement disorders. (2005) Radiologic clinics of North America. 43 (1): 93-106. doi:10.1016/j.rcl.2004.08.002 - Pubmed
- 9. Rakshi JS, Pavese N, Uema T, Ito K, Morrish PK, Bailey DL, Brooks DJ. A comparison of the progression of early Parkinson's disease in patients started on ropinirole or L-dopa: an 18F-dopa PET study. (2002) Journal of neural transmission (Vienna, Austria : 1996). 109 (12): 1433-43. doi:10.1007/s00702-002-0753-0 - Pubmed
- 10. Khan NL, Valente EM, Bentivoglio AR, Wood NW, Albanese A, Brooks DJ, Piccini P. Clinical and subclinical dopaminergic dysfunction in PARK6-linked parkinsonism: an 18F-dopa PET study. (2002) Annals of neurology. 52 (6): 849-53. doi:10.1002/ana.10417 - Pubmed