Alanine is a non-essential amino acid that can be produced from the breakdown of proteins or carbohydrates. It is involved in the glucose-alanine cycle between muscle and liver.
Jung Myung Seok, Kim Dong Hoon, Kim Hyun, et al.. l-Alanine activates hepatic AMP-activated protein kinase and modulates systemic glucose metabolism. Nutrients (2018). https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6197624/
Glutamine is the most abundant free amino acid in the body and is involved in protein synthesis, immune function, and intestinal health. Glutamine levels may reflect overall protein status.
Zhang M, Guo Y, Jiang J, Zhang Z, Wang J, Liu J. Glutamine as an Anti-Fatigue Amino Acid in Sports Nutrition. Nutrients (2019). https://www.mdpi.com/2072-6643/11/4/861
Isoleucine is the third branched-chain amino acid that plays a central role in protein synthesis and energy metabolism.
Chung-Yang Yeh, Lucas C.S. Chini, Jessica W. Davidson, Gonzalo G. Garcia, Meredith S. Gallagher, Isaac T. Freichels, Mariah F. Calubag, Allison C. Rodgers, Cara L. Green, Reji Babygirija. Late-life isoleucine restriction promotes physiological and molecular signatures of healthy aging. Aging Cell (2023). https://onlinelibrary.wiley.com/doi/full/10.1111/acel.13750
Hao Liu, Jun Sun, Shuang Jiang, Na Jiao, Li Huang, Xiang Xuan Yuan, Guan Qing Li, Wei Yang. Effects of dietary isoleucine supplementation on the production performance, health status and cecal microbiota of Arbor Acre broiler chickens. Microorganisms (2023). https://www.mdpi.com/2076-2607/11/2/236
Shi Ma, Kai Zhang, Shi Shi, Li Xin, Chun Cao, Pei Chen, Hao Liu. Low-protein diets supplemented with isoleucine alleviate lipid deposition in broilers through activating 5′ adenosine monophosphate-activated protein kinase and janus kinase 2/signal transducer and activator of transcription 3 signaling pathways. Poultry Science (2023). https://academic.oup.com/ps/article/102/5/10116867
EFSA Panel on Additives and Products or Substances used in Animal Feed (FEEDAP). The nutritional role of the amino acid l-isoleucine: safety and efficacy of l-isoleucine produced by fermentation with Corynebacterium glutamicum ATCC 13032 for all animal species. EFSA Journal (2020). https://efsa.onlinelibrary.wiley.com/doi/full/10.2903/j.efsa.2020.6021
Leucine is one of the branched-chain amino acids that are key components of proteins. Leucine levels correlate with protein consumption and muscle protein synthesis.
Morton, R. W., et al.. Association of postprandial postexercise muscle protein synthesis with plasma leucine variables. Physiological Reports (2023). https://pubmed.ncbi.nlm.nih.gov/37537134/
Lysine is an essential amino acid that is critical for protein synthesis, especially for collagen, and may be a limiting factor in some cereal-based diets.
Britannica. Lysine, an amino acid released in the hydrolysis of many common proteins but present in small amounts or lacking in certain plant proteins. Britannica (2024). https://www.britannica.com/science/lysine
Methionine is an essential amino acid that plays important roles in protein synthesis, methylation reactions, and the production of cysteine and glutathione.
Proline is a non-essential amino acid that is important for the structure of collagen and other proteins. Proline levels may be influenced by protein intake.
Sergey Melnikov, Justine Mailliot, Lukas Rigger, Sandro Neuner, Byung‐Sik Shin, Gulnara Yusupova, Thomas E Dever, Ronald Micura. Molecular insights into protein synthesis with proline residues. PMC (2016). https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5283605/
Stem Cell Fate Laboratory, Institute of Genetics and Biophysics “A. Buzzati Traverso”, Consiglio Nazionale delle Ricerche, Naples, Italy. The Multifaceted Roles of Proline in Cell Behavior. Frontiers in Cell and Developmental Biology (2021). https://www.frontiersin.org/articles/10.3389/fcell.2021.728576/full
Sergey Melnikov, Justine Mailliot, Lukas Rigger, Sandro Neuner, Byung‐Sik Shin, Gulnara Yusupova, Thomas E Dever, Ronald Micura. Molecular insights into protein synthesis with proline residues. PMC (2016). https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5283605/
Tyrosine is a non-essential amino acid that can be produced from phenylalanine. It is a precursor for neurotransmitters and hormones and is found in many proteins.
Mahta Moinpour, Natalie K. Barker, Lindsay E. Guzman, John C. Jewett, Paul R. Langlais, Jacob C. Schwartz. Discriminating changes in protein structure using tyrosine conjugation. Journal of Protein Science (2023). https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7380675/
Shohei Koide, Sachdev S. Sidhu. The Importance of Being Tyrosine: Lessons in Molecular Recognition from Minimalist Synthetic Binding Proteins. Journal of Molecular Biology (2011). https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2829252/
N. Bagheri, H. Chen, M. Rabasovic, et al.. Non-fluorescent transient states of tyrosine as a basis for label-free protein conformation and interaction studies. Scientific Reports (2024). https://www.nature.com/articles/s41598-024-57054-6
Valine, like leucine, is a branched-chain amino acid that is an important building block for proteins, especially in muscle.
Radzicka, A., & Wolfenden, R.. Clusters of isoleucine, leucine, and valine side chains define cores of stability in partially folded states of TIM barrel proteins. Journal of Molecular Biology (2016). https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4815418/
Wang, Y., Li, X., Zhang, Y., Zhang, Y., & Zhang, L.. Dietary Valine Ameliorated Gut Health and Accelerated the Development of Secondary Follicles in Laying Hens. Animals (2021). https://www.mdpi.com/2076-2615/11/8/2294
