The essential oil composition of four genetically diverse stocks of Murraya koenigii leaves cultivated at the CIMAP Research Farm, Lucknow, were analysed by GC and GC-MS. The oil from the stock of the northern Indian plains, Lucknow, showedˇ-pinene (70.0%),ˇ-caryophyllene (6.5%) and˛-pinene (5.4%) as the major constituents, while the oil from the stock of the lower Himalayan range, Pant Nagar, showed˛-pinene (65.7%), -pinene (13.4%) andˇ-phellandrene (7.4%) as the major constituents. In contrast to the above, the oil from the stock of southern India, Kozhikode, showedˇ-caryophyllene (53.9%), aromadendrene (10.7%) and˛-selinene (6.3%) as the major constituents. On the other hand, the oil from the stock of eastern India, Bhubaneshwar, showeď -phellandrene (30.2%),ˇ-caryophyllene (24.2%),˛-pinene (15.0%), (E)-ˇ-ocimene (5.0%) and aromadendrene (4.5%) as the major constituents. The GC-MS analysis of the stock oil samples from the northern Indian plains, lower Himalayan range, southern and eastern India resulted in the identification of 65, 56, 57 and 66, constituents, representing 99.2%, 98.8%, 87.4% and 98.2% of the oils, respectively.

We explore a novel phenomenon of focused ion beam (FIB) induced bending of carbon nanopillars or cantilever structures. The bending occurs towards the ion beam during scanning. The explanation of this bending has been sought on the basis of a model which considers temperature rise and gradients caused by the impinging ion beam. The process is controllable and reversible, which makes it highly suitable for in situ manipulation to make desired 3D shapes by the piecewise bending of the nanopillars and cantilever structures during their fabrication using electron beam or FIB chemical vapor deposition (EB-CVD or FIB-CVD). Its usefulness in the fabrication of nanosize mechanical components has been demonstrated by making a branch structure from a single cantilever.

No abstract

Toxoplasma gondii (TgADF) belongs to a functional subtype characterized by strong G-actin sequestering activity and low F-actin severing activity. Among the characterized ADF/cofilin proteins, TgADF has the shortest length and is missing a C-terminal helix implicated in F-actin binding. In order to understand its characteristic properties, we have determined the solution structure of TgADF and studied its backbone dynamics from 15N-relaxation measurements. TgADF has conserved ADF/cofilin fold consisting of a central mixed β-sheet comprised of six β-strands that are partially surrounded by three α-helices and a C-terminal helical turn. The high G-actin sequestering activity of TgADF relies on highly structurally and dynamically optimized interactions between G-actin with the G-actin binding surface of TgADF. The equilibrium dissociation constant for TgADF and rabbit muscle G-actin was 23.81 nM, as measured by ITC, which reflects very strong affinity of TgADF and G-actin interactions. The F-actin binding site of TgADF is partially formed, with a shortened F-loop that does not project out of the ellipsoid structure and a C-terminal helical turn in place of the C-terminal helix α4. Yet, it is more rigid than the typical F-actin binding site of Leishmania donovani cofilin. Experimental observations and structural features do not support the interaction of PIP2 with TgADF, and PIP2 does not affect the interaction of TgADF with G-actin. Overall, this study suggests that conformational flexibility of G-actin binding sites enhances the affinity of TgADF for G-actin, while conformational rigidity of F-actin binding sites of conventional ADF/cofilins is necessary for stable binding to F-actin.

Rv3619c and Rv3620c are the secretory, antigenic proteins of the ESAT-6 ⁄ CFP-10 family of Mycobacterium tuberculosis H37Rv. In this article, we show that Rv3619c interacts with Rv3620c to form a 1 : 1 heterodimeric complex with a dissociation constant (K d ) of 4.8 · 10)7 M. The thermal unfolding of the heterodimer was completely reversible, with a T m of 48°C. The comparative thermodynamics and thermal unfolding analysis of the Rv3619c-Rv3620c dimer, the ESAT-6-CFP-10 dimer and another ESAT family heterodimer, Rv0287-Rv0288, revealed that the binding strength and stability of Rv3619c-Rv3620c are relatively lower than those of the other two pairs. Molecular modeling and docking studies predict the structure of Rv3619c-Rv3620c to be similar to that of ESAT-6-CFP-10. Spectroscopic studies revealed that, in an acidic environment, Rv3619c and Rv3620c lose their secondary structure and interact weakly to form a complex with a lower helical content, indicating that Rv3619c-Rv3620c is destabilized at low pH. These results, combined with those of previous studies, suggest that unfolding of the proteins is required for dissociation of the complex and membrane binding. In the presence of membrane mimetics, the a-helical contents of Rv3619c and Rv3620 increased by 42% and 35%, respectively. In mice, the immune response against Rv3619c protein is characterized by increased levels of interferon-c, interleukin-12 and IgG 2a , indicating a dominant Th1 response, which is mandatory for protection against mycobacterial infection. This study therefore emphasizes the potential of Rv3619c as a subunit vaccine candidate.