Heterogeneous nanomechanical properties of type I collagen in longitudinal direction

Biomechanics and Modeling in Mechanobiology - Collagen is an abundant structural biopolymer in mammal vertebrates, providing structural support as well as mechanical integrity for connective...     

Facile synthesis, ex-vivo and in vitro screening of 3-sulfonamide derivative of 5-(4-chlorophenyl)-1-(2,4-dichlorophenyl)-4-methyl-1H-pyrazole-3-carboxylic acid piperidin-1-ylamide (SR141716) a potent CB1 receptor antagonist

Facile synthesis of biaryl pyrazole sulfonamide derivative of 5-(4-chlorophenyl)-1-(2,4-dichlorophenyl)-4-methyl-1H-pyrazole-3-carboxylic acid piperidin-1-ylamide (SR141716, 1) and an investigation of the effect of replacement of the –CO group in the compound 1 by the –SO₂ group in the aminopiperidine region is reported. Primary ex-vivo pharmacological testing and in vitro screening of sulfonamide derivative 2 showed the loss of CB1 receptor antagonism.     

Antimicrobial protein from Streptomyces fulvissimus inhibitory to methicillin resistant Staphylococcus aureus

Fermented culture of Streptomyces fulvissimus was found to secrete an antibacterial protein inhibitory to Micrococcus luteus, Bacillus subtilis, Bacillus cereus and methicillin resistant Staphylococcus aureus (MRSA) strains. The extracellular protein from the fermented culture on concentration revealed a high molecular weight peptide of 63kDa on SDS-PAGE gel and the region on gel displayed inhibitory activity against methicillin resistant Staphylococcus aureus. Bioactivity of the extra cellular protein was non-sensitive to proteinase K, alpha chymotrypsin, protease, EDTA (ethylene diamine tetra acetic acid), PMSF (phenyl methyl sulfonyl fluoride) and DMSO (dimethyl sulfoxide) but partially susceptible to amylase and heat. Glycoprotein nature of the proteinaceous compound was confirmed by periodic acid schiffs (PAS) staining. The secretary protein of S. fulvissimus demonstrated a significant activity against MRSA strain. It could be an important source for developing new drugs to control multidrug resistant gram positive bacteria.     

Bacteriocin: safest approach to preserve food products

Start of the 21st century with its universal call to feed the hungry is an appropriate time to refocus attention on food security and especially the impact of biopatenting on poor communities who are the primary victims of hunger in our world. Antibacterial metabolites of lactic acid bacteria and Bacillus spp have potential as natural preservatives to control the growth of spoilage and pathogenic bacteria in food. Among them, bacteriocin is used as a preservative in food due to its heat stability, wider pH tolerance and its proteolytic activity. Due to thermo stability and pH tolerance it can withstand heat and acidity/alkanity of food during storage condition. Bacteriocin are ribosomally synthesized peptides originally defined as proteinaceous compound affecting growth or viability of closely related organisms. Research is going on extensively to explore the nascent field of biopreservation. Scientists all over the world are showing their keen interest to isolate different types of bacteriocin producing strains and characterize bacteriocin produced by them for food preservation.     

Integrin alpha2-mediated ERK and calpain activation play a critical role in cell adhesion and motility via focal adhesion kinase signaling: identification of a novel signaling pathway

Higher levels of focal adhesion kinase (FAK) are expressed in colon metastatic carcinomas. However, the signaling pathways and their mechanisms that control cell adhesion and motility, important components of cancer metastasis, are not well understood. We sought to identify the integrin-mediated mechanism of FAK cleavage and downstream signaling as well as its role in motility in human colon cancer GEO cells. Our results demonstrate that phosphorylated FAK (tyrosine 397) is cleaved at distinct sites by integrin signaling when cells attach to collagen IV. Specific blocking antibodies (clone P1E6) to integrin alpha2 inhibited FAK activation and cell motility (micromotion). Ectopic expression of the FAK C-terminal domain FRNK attenuated FAK and ERK phosphorylation and micromotion. Calpain inhibitor N-acetyl-leucyl-leucyl-norleucinal blocked FAK cleavage, cell adhesion, and micromotion. Antisense approaches established an important role for mu-calpain in cell motility. Expression of wild type mu-calpain increased cell micromotion, whereas its point mutant reversed the effect. Further, cytochalasin D inhibited FAK phosphorylation and cleavage, cell adhesion, locomotion, and ERK phosphorylation, thus showing FAK activation downstream of actin assembly. We also found a pivotal role for FAK Tyr(861) phosphorylation in cell motility and ERK activation. Our results reveal a novel functional connection between integrin alpha2 engagement, FAK, ERK, and mu-calpain activation in cell motility and a direct link between FAK cleavage and enhanced cell motility. The data suggest that blocking the integrin alpha2/FAK/ERK/mu-calpain pathway may be an important strategy to reduce cancer progression.     

Chain collapse of an amyloidogenic intrinsically disordered protein

Natively unfolded or intrinsically disordered proteins (IDPs) are under intense scrutiny due to their involvement in both normal biological functions and abnormal protein misfolding disorders. Polypeptide chain collapse of amyloidogenic IDPs is believed to play a key role in protein misfolding, oligomerization, and aggregation leading to amyloid fibril formation, which is implicated in a number of human diseases. In this work, we used bovine κ-casein, which serves as an archetypal model protein for amyloidogenic IDPs. Using a variety of biophysical tools involving both prediction and spectroscopic techniques, we first established that monomeric κ-casein adopts a collapsed premolten-globule-like conformational ensemble under physiological conditions. Our time-resolved fluorescence and light-scattering data indicate a change in the mean hydrodynamic radius from ∼4.6 nm to ∼1.9 nm upon chain collapse. We then took the advantage of two cysteines separated by 77 amino-acid residues and covalently labeled them using thiol-reactive pyrene maleimide. This dual-labeled protein demonstrated a strong excimer formation upon renaturation from urea- and acid-denatured states under both equilibrium and kinetic conditions, providing compelling evidence of polypeptide chain collapse under physiological conditions. The implication of the IDP chain collapse in protein aggregation and amyloid formation is also discussed.