Karaca Tuğçe Deniz, Doğan Alev
Health Service Vocational School, University of Gazi, Golbası, Ankara, Turkey.
Department of Science Education, Faculty of Gazi Education, University of Gazi, Teknikokullar, 06500, Ankara, Turkey.
Amino Acids. 2023 Apr;55(4):443-450. doi: 10.1007/s00726-023-03238-9. Epub 2023 Jan 24.
The protonation constants are one of the most fundamental properties of biological molecules. The determination of the constants of the dipeptide is interesting and necessary for a full understanding of its activities in biological process. In this study, the protonation constants of some aliphatic alanine dipeptides (alanyl-alanine, alanyl-phenylalanine, alanyl-valine, alanyl-leucine, and alanyl-methionine) were studied in water and ethanol-water mixtures (20%ethanol-80%water;40%ethanol-60%water;60%ethanol-40%water, (v/v)) at 25 ± 0.1 °C under nitrogen atmosphere and ionic strength at 0.10 mol L by potentiometry. The constants of the systems were calculated using Best computer program. The effects of the different amino acids bound to the alanine on the acidity of the alanyl dipeptides were investigated. The constants were influenced by changes in solvent composition and their variations were discussed in terms of solvent and structural properties.
质子化常数是生物分子最基本的性质之一。测定二肽的常数对于全面了解其在生物过程中的活性很有趣且必要。在本研究中，通过电位滴定法在25±0.1℃、氮气气氛和离子强度为0.10 mol/L的条件下，研究了一些脂肪族丙氨酸二肽（丙氨酰 - 丙氨酸、丙氨酰 - 苯丙氨酸、丙氨酰 - 缬氨酸、丙氨酰 - 亮氨酸和丙氨酰 - 甲硫氨酸）在水和乙醇 - 水混合物（20%乙醇 - 80%水；40%乙醇 - 60%水；60%乙醇 - 40%水，(v/v)）中的质子化常数。使用Best计算机程序计算体系的常数。研究了与丙氨酸相连的不同氨基酸对丙氨酰二肽酸度的影响。这些常数受溶剂组成变化的影响，并根据溶剂和结构性质对其变化进行了讨论。
