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In this work, the influence of dipeptide composition on protein thermostability was studied. After comparing the normalized dipeptide composition between mesophilic proteins and (hyper)thermophilic proteins, we concluded that when organism optimal growth temperature increased, for archaeal proteins, the compositions of VK, KI, YK, IK, KV, KY, and EV increased significantly and the compositions of DA, AD, TD, DD, DT, HD, DH, DR, and DG decreased significantly; and for bacterial proteins, the compositions of KE, EE, EK, YE, VK, KV, KK, LK, EI, EV, RK, EF, KY, VE, KI, KG, EY, FK, KF, FE, KR, VY, MK, WK, and WE increased significantly and the compositions of WQ, AA, QA, MQ, AW, QW, QQ, RQ, QH, HQ, AD, AQ, WL, QL, HA, and DA decreased significantly. So these characteristic dipeptides are correlative to protein thermostability. At the same time, the influence of single amino acid composition on protein thermostability was also studied for comparison. We found that the influence of single amino acid composition could be deduced from the influence of dipeptide composition. So we thought that the influence of dipeptide composition on protein thermostability is larger than the influence of amino acid composition. The characteristic dipeptides not only describe the dipeptides that influence protein thermostability significantly but also show the relationship among significant single amino acids that influence protein thermostability.

The oncogenesis and progression of gastric cancer are closely correlated with the complex regulatory relationships among messenger RNA (mRNA), long noncoding RNA (lncRNA), and microRNA (miRNA). After constructing the gastric cancer lncRNA‐miRNA‐mRNA regulatory network, we analyzed the network topology properties and found that lncRNA ADAMTS9‐AS2 and C20orf166‐AS1 and miRNA hsa‐mir‐204 are key nodes. Further functional enrichment analysis and survival analysis were performed on these key nodes and the RNAs interacting with them. We found that CHRM2, ANGPT2, and COL1A1 interacting with ADAMTS9‐AS2 are enriched in the PI3K‐Akt signaling pathway, and low expression of the ADAMTS9‐AS2 is closely related to the prognosis of patients. Abnormal expression of CACNA1H, FLNA, and FLNC interacting with lncRNA C20orf166‐AS1 is associated with MAPK signaling pathway in gastric cancer. In addition, the downregulated miRNA hsa‐mir‐204 promotes invasion and proliferation of gastric cancer cells by regulating the abnormal expression of mRNAs (CHRDL1 and NPTX1) and lncRNAs (ADAMTS9‐AS2, NKX2‐1‐AS1, TLR8‐AS1, and VCAN‐AS1). This study systematically analyzed the lncRNA‐miRNA‐mRNA regulatory network of gastric cancer, which not only has a new understanding of the pathogenesis of gastric cancer, but also provides new insights for the early diagnosis and treatment of gastric cancer.