Finkina Ekaterina I, Melnikova Daria N, Bogdanov Ivan V, Ignatova Anastasia A, Ovchinnikova Tatiana V
M. M. Shemyakin & Yu. A. Ovchinnikov Institute of Bioorganic Chemistry, The Russian Academy of Sciences, Miklukho-Maklaya str., 16/10, 117997 Moscow, Russia.
Department of Biotechnology, I. M. Sechenov First Moscow State Medical University, Trubetskaya str., 8-2, 119991 Moscow, Russia.
Membranes (Basel). 2021 Sep 30;11(10):754. doi: 10.3390/membranes11100754.
Previously, we have demonstrated that Gly m 4, one of the major soybean allergens, could pass through the Caco-2 epithelial barrier and have proposed a mechanism of sensitization. However, it is not known yet whether Gly m 4 can reach the intestine in its intact form after digestion in stomach. In the present work, we studied an influence of various factors including lipids (fatty acids and lysolipids) on digestibility of Gly m 4. Using fluorescent and CD spectroscopies, we showed that Gly m 4 interacted with oleic acid and LPPG (lyso-palmitoyl phosphatidylglycerol), but its binding affinity greatly decreased under acidic conditions, probably due to the protein denaturation. The mimicking of gastric digestion revealed that Gly m 4 digestibility could be significantly reduced with the change of pH value and pepsin-to-allergen ratio, as well as by the presence of LPPG. We suggested that the protective effect of LPPG was unlikely associated with the allergen binding, but rather connected to the pepsin inhibition due to the lipid interaction with its catalytic site. As a result, we assumed that, under certain conditions, the intact Gly m 4 might be able to reach the human intestine and thereby could be responsible for allergic sensitization.
此前，我们已经证明，大豆主要过敏原之一的Gly m 4能够穿过Caco-2上皮屏障，并提出了一种致敏机制。然而，目前尚不清楚Gly m 4在胃中消化后是否能以完整形式到达肠道。在本研究中，我们研究了包括脂质（脂肪酸和溶血脂质）在内的各种因素对Gly m 4消化率的影响。通过荧光光谱和圆二色光谱，我们发现Gly m 4与油酸和溶血棕榈酰磷脂酰甘油（LPPG）相互作用，但其结合亲和力在酸性条件下大大降低，这可能是由于蛋白质变性所致。模拟胃消化的实验表明，随着pH值、胃蛋白酶与过敏原比例的变化以及LPPG的存在，Gly m 4的消化率会显著降低。我们认为，LPPG的保护作用不太可能与过敏原结合有关，而更可能是由于脂质与胃蛋白酶催化位点相互作用而导致胃蛋白酶受到抑制。因此，我们推测，在某些条件下，完整的Gly m 4可能能够到达人体肠道，从而可能导致过敏致敏。
