Backbone circularization of protein is a powerful method to improve its structural stability. In this paper, we presumed that a tight connection leads to much higher stability. Therefore, we designed circularized variants of a granulocyte-colony stimulating factor (G-CSF) with a structurally optimized terminal connection. To estimate the appropriate length of the connection, we surveyed the Protein Data Bank to find local structures as a model for the connecting segment. We set the library of local structures composed of “helix–loop–helix,” subsequently selected entries similar to the G-CSF terminus, and finally sorted the hit structures according to the loop length. Two, five, or nine loop residues were frequently observed; thus, three circularized variants (C163, C166, and C170) were constructed, prepared, and evaluated. All circularized variants demonstrated a higher thermal stability than linear G-CSF (L175). In particular, C166 that retained five connecting residues demonstrated apparent T m values of 69.4 °C, which is 8.7 °C higher than that of the circularized variant with no truncation (C177), indicating that the optimization of the connecting segment is effective for enhancing the overall structural stability. C166 also showed higher proteolytic stability against both endoprotease and exopeptidase than L175. We anticipate that the present study will contribute to the improvement in the general design of circularized protein and development of G-CSF biobetters.
Peptic ulcer disease (PUD) is a multifactorial and complex disease caused by an imbalance of protective and aggressive factors (endogenous and exogenous). Despite advances in recent years, it is still responsible for substantial mortality and triggering clinical problems. Over the last decades, the understanding of PUD has changed a lot with the discovery of Helicobacter pylori infection. However, this disease continues to be a challenge due to side-effects, incidence of relapse from use of various anti-ulcer medicines, and the rapid appearance of antimicrobial resistance with current H. pylori therapies. Consequently, there is the need to identify more effective and safe anti-ulcer agents. The search for new therapies with natural products is a viable alternative and has been encouraged. The literature reports the importance of monoterpenes based on the extensive pharmacological action of this class, including wound healing and anti-ulcerogenic agents. In the present study, 20 monoterpenes with anti-ulcerogenic properties were evaluated by assessing recent in vitro and in vivo studies. Here, we review the anti-ulcer effects of monoterpenes against ulcerogenic factors such as ethanol, nonsteroidal anti-inflammatory drugs (NSAIDs), and Helicobacter pylori, highlighting challenges in the field.Biomolecules 2020, 10, 265 2 of 18 PUD results from an imbalance in mucosal defensive factors, such as mucus secretion, bicarbonate efflux, endogenous antioxidant, cell regeneration, continuous synthesis and release of prostaglandin E 2 (PGE 2 ), nitric oxide (NO), and sulfhydryl compounds (SH); and aggressive agents such as smoking, alcohol consumption, dietary factors, stress, prolonged and excessive intake of nonsteroidal anti-inflammatory drugs (NSAIDs), and Helicobacter pylori (H. pylori) infection, among others [6][7][8][9]. For a long time, it was believed that the main factor implicated in the development and progression of peptic ulceration was an hypersecretory acidic environment and together with dietary factors and/or stress was thought to cause most of PUD. But the discovery of H. pylori infection and the widespread use of NSAIDs in the second half of the 20 th century changed this perception. In recent years, peptic ulcer has been found to have multiple causes-H. pylori infection, NSAIDs, smoking, alcohol consumption, stress, lifestyle, and genetic predispositions are determined as major risk factors for the development of PUD [2]. PathophysiologyUnder normal conditions, gastric and duodenal mucosa integrity is maintained by the mucus-bicarbonate barrier, the neutral pH, and continuous epithelial cell renewal [10,11]. PGE 2 stimulates cell proliferation, mucus, and bicarbonate production, promoting a crucial function in mucosa preservation. Another vital factor in gastric homeostasis is adequate blood flow. The NO and PGs are responsible for the maintenance of proper perfusion to the gastric mucosa, assuring the delivery of oxygen and nutrients, as well as removing toxic metabolites, preventing damages to the ti...
To deterinne whether the presence of bacterial flora contributes to the ontogenic development of macrophage function, the ability of macrophages to release superoxide anion (O2-) in response to stimulation with phorbol myristate acetate was compared in conventional and germfree mice of various ages after birth.
The aim of this research was to compare the accuracy of urinary protein/creatinine ratio (PCR) and albumin/creatinine ratio (ACR) in defining optimal cut-off points to rule-out significant proteinuria (>300 mg/24 h) in pregnancy. The secondary outcome measure was to determine the investigation of choice to evaluate proteinuria used by maternity units in the UK. PCR and ACR were calculated on first (PCR1, ACR1) void urine samples of the 24-hour urinary protein collection (24UP). Sensitivity and specificity was calculated for different cut-off points for PCR1 and ACR1 to rule-out significant proteinuria. An online survey was sent to RCOG members questioning them on their investigation of choice to evaluate proteinuria. We concluded from our results that both PCR and ACR are good rule-out tests for significant proteinuria in pregnancy using cut-off points of <20 mg/mmol and <2.5 mg/mmol. PCR is the investigation of choice in 56% of UK units studied.
It has been reported that a point mutation of minichromosome maintenance (MCM)4 causes mammary carcinoma, and it deregulates DNA replication to produce abnormal chromosome structures. To understand the effect of this mutation at level of MCM2-7 interaction, we examined the effect of the same mutation of human MCM4 on the complex formation with MCM6 and MCM7 in insect cells. Human MCM4/6/7 complexes containing the mutated MCM4 were formed, but the hexameric complex formation was not evident in comparison with those containing wild-type MCM4. In binary expression of MCM4 and MCM6, decreased levels of MCM6 were recovered with the mutated MCM4, compared with wild-type MCM4. These results suggest that this mutation of MCM4 perturbs proper interaction with MCM6 to affect complex formation of MCM4/6/7 that is a core structure of MCM2-7 complex. Consistent with this notion, nuclear localization and MCM complex formation of forcedly expressed MCM4 in human cells are affected by this mutation. Thus, the defect of this mutant MCM4 in interacting with MCM6 may generate a decreased level of chromatin binding of MCM2-7 complex.
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