Faculty of Pure and Applied Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8573, Japan.
Alliance Protein Laboratories, San Diego, CA 92121, United States.
Int J Biol Macromol. 2018 Jul 15;114:497-503. doi: 10.1016/j.ijbiomac.2018.03.011. Epub 2018 Mar 2.
Allantoin is widely used in pharmaceutical and cosmetic products, and is composed of a hydantoin ring and a ureido group. Recent reports showed that allantoin suppresses thermal aggregation of hen egg white lysozyme (LYZ). However, structural insight into the properties of allantoin on protein aggregation and whether allantoin controls the aggregation of other proteins under different stress conditions remain unclear. Here we studied the structural properties of allantoin in terms of its effects on protein aggregation by comparing allantoin with urea and hydantoin. Furthermore, we analyzed the effects of allantoin and its derivatives on the aggregation of LYZ, carbonic anhydrase from bovine erythrocytes (BCA), albumin from chicken egg white (OVA), and immunoglobulin G (IgG) by various stresses in comparison with arginine. These four proteins are widely different in charged state and molecular size. Allantoin suppressed the aggregation and inactivation of LYZ comparing to arginine without affecting the melting temperature of proteins, and was responsible for the slightly improved formation of soluble oligomers and insoluble aggregates of IgG with thermal and acidic stresses. In contrast, hydantoin increased the solubility of aromatic amino acids more effectively than arginine and allantoin. The structural properties underlying the observed effects of allantoin as an aggregation suppressor include hydrophobic interactions between hydantoin moiety and aromatic ring on the surface of proteins, which is reflected on the difference between allantoin and arginine. These results show that the backbone of hydantoin ring may be a new category of additives for development of small aggregation suppressors.
尿囊素广泛应用于药物和化妆品产品，由尿嘧啶环和脲基组成。最近的报告表明，尿囊素能抑制鸡卵清溶菌酶（LYZ）的热聚集。然而，尿囊素对蛋白质聚集的特性以及在不同应激条件下是否控制其他蛋白质的聚集的结构见解尚不清楚。在这里，我们通过将尿囊素与尿素和海因比较，研究了尿囊素对蛋白质聚集的结构特性及其对蛋白质聚集的影响。此外，我们分析了尿囊素及其衍生物对 LYZ、牛红细胞碳酸酐酶（BCA）、鸡卵清白蛋白（OVA）和免疫球蛋白 G（IgG）在与精氨酸比较的各种应激下聚集的影响。这四种蛋白质在荷电状态和分子大小上有很大的不同。与精氨酸相比，尿囊素抑制 LYZ 的聚集和失活，而不影响蛋白质的熔点，并负责在热和酸性应激下略微改善 IgG 的可溶性低聚物和不溶性聚集体的形成。相比之下，海因比精氨酸和尿囊素更有效地增加芳香族氨基酸的溶解度。作为聚集抑制剂的尿囊素的观察到的效果的结构特性包括海因部分与蛋白质表面的芳环之间的疏水相互作用，这反映在尿囊素和精氨酸之间的差异上。这些结果表明，海因环的骨架可能是开发小分子聚集抑制剂的一个新类别添加剂。
