The proteolytic specificity of rhodostoxin, the major hemorrhagin from Calloselasma rhodostoma (Malayan pit viper) venom was investigated using oxidized B-chain of bovine insulin as substrate. Six peptide bonds were cleaved: Ser9-Hist10, His10-Leu11, Ala14-Leu15, Tyr16-Leu17, Gly20-Glu21 and Phe24-Phe25. Deglycosylated rhodostoxin, however, cleaved primarily at Arg22-Gly23.
The prevalence of atherosclerosis has increased significantly in the recent years due to sedentary lifestyle and high-fat diet. However, the association between saturated fat intake and the increased risk for atherosclerotic cardiovascular diseases remains heavily debated. Lauric acid belongs to the saturated fatty acid group and its unique medium chain fatty acid properties are proven to be beneficial to humans in many ways. Thus, the aim of this project is to investigate the effect of lauric acid on the expression of a disintegrin and metalloproteinase with thrombospondin motifs (ADAMTS) genes-ADAMTS-1, ADAMTS-4, and ADAMTS-5-in macrophages. These genes encode for proteases that participate in the extracellular matrix remodeling and they play important roles in the vulnerability of atherosclerotic plaque. Here, we show that the treatment of 20 µM of lauric acid successfully reduced both transcriptional and translational expressions of these genes in THP-1 differentiated macrophages after 24-h incubation. Further cell signaling experiments using a panel of kinase inhibitors and phosphorylated antibodies proved that lauric acid down-regulated ADAMTS-1 by reducing the activation of PI3K and JNK at Tyr458 and Tyr185, respectively. Finally, JNK1 siRNA knockdown assay confirmed that ADAMTS-1 was regulated through JNK pathway, and lauric acid interfered with this pathway to down-regulate ADAMTS-1 expression. Although preliminary, this present study indicates that lauric acid has the potential to stabilize atherosclerotic plaque and may prevent thrombosis by interfering with the ADAMTS-1 expression through PI3K/JNK pathways.
Burkholderia cepacia complex (Bcc) are opportunistic pathogens implicated with nosocomial infections, and high rates of morbidity and mortality, especially in individuals with cystic fibrosis (CF). B. cepacia are naturally resistant to different classes of antibiotics, and can subvert the host innate immune responses by producing quorum sensing (QS) controlled virulence factors and biofilms. It still remains a conundrum as to how exactly the bacterium survives the intracellular environment within the host cells of CF patients and immunocompromised individuals although the bacterium can invade human lung epithelial cells, neutrophils, and murine macrophages. The mechanisms associated with intracellular survival in the airway epithelial cells and the role of QS and virulence factors in B. cepacia infections in cystic fibrosis remain largely unclear. The current review focuses on understanding the role of QS-controlled virulence factors and biofilms, and provides additional impetus to understanding the potentials of QS-inhibitory strategies against B. cepacia.
Recombinant elastase strain K overexpressed from E. coli KRX/pCon2(3) was purified to homogeneity by a combination of hydrophobic interaction chromatography and ion exchange chromatography, with a final yield of 48% and a 25-fold increase in specific activity. The purified protein had exhibited a first ever reported homodimer size of 65 kDa by SDS-PAGE and MALDI-TOF, a size which is totally distinct from that of typically reported 33 kDa monomer from P. aeruginosa. The organic solvent stability experiment had demonstrated a stability pattern which completely opposed the rules laid out in previous reports in which activity stability and enhancement were observed in hydrophilic organic solvents such as DMSO, methanol, ethanol and 1-propanol. The high stability and enhancement of the enzyme in hydrophilic solvents were explained from the view of alteration in secondary structures. Elastinolytic activation and stability were observed in 25 and 50% of methanol, respectively, despite slight reduction in α-helical structure caused upon the addition of the solvent. Further characterization experiments had postulated great stability and enhancement of elastase strain K in broad range of temperatures, pHs, metal ions, surfactants, denaturing agents and substrate specificity, indicating its potential application in detergent formulation.