Ala-Leu-Ala-Leu is a peptide. Ala-Leu-Ala-Leu can be used for the research of experiment research[1].
References
[1] Irtaza Hassan, et al. Effect of the Hydration Shell on the Carbonyl Vibration in the Ala-Leu-Ala-Leu Peptide. Molecules. 2021 Apr 8;26(8):2148. DOI:10.3390/molecules26082148