Structural studies of hemoglobin from two flightless birds, ostrich and turkey: insights into their differing oxygen-binding properties

Crystal structures of hemoglobin (Hb) from two flightless birds, ostrich (Struthio camelus) and turkey (Meleagris gallopova), were determined. The ostrich Hb structure was solved to a resolution of 2.22 Å, whereas two forms of turkey Hb were solved to resolutions of 1.66 Å (turkey monoclinic structure; TMS) and 1.39 Å (turkey orthorhombic structure; TOS). Comparison of the amino-acid sequences of ostrich and turkey Hb with those from other avian species revealed no difference in the number of charged residues, but variations were observed in the numbers of hydrophobic and polar residues. Amino-acid-composition-based computation of various physical parameters, in particular their lower inverse transition temperatures and higher average hydrophobicities, indicated that the structures of ostrich and turkey Hb are likely to be highly ordered when compared with other avian Hbs. From the crystal structure analysis, the liganded state of ostrich Hb was confirmed by the presence of an oxygen molecule between the Fe atom and the proximal histidine residue in all four heme regions. In turkey Hb (both TMS and TOS), a water molecule was bound instead of an oxygen molecule in all four heme regions, thus confirming that they assumed the aqua-met form. Analysis of tertiary- and quaternary-structural features led to the conclusion that ostrich oxy Hb and turkey aqua-met Hb adopt the R-/RH-state conformation.

Bio-functional enhancement of plant based-haemagglutinin by fusion with IgMFc

The creation of recombinant oligomeric haemagglutinin proteins from A/H5N1 virus is a new concern for many scientists. In this study, the gene encoding the haemagglutinin protein (H5TG) derived from virus A/duck/Vietnam/TG24-01/2005 was fused with three different motifs (GCN4pII, GCN4pII-IgMFc and GCN4pII-ELP-IgMFc) in order to form three recombinant proteins (trimeric H5TGpII, oligomeric H5TGpII-IgMFc and ELPylated oligomeric H5TGpII-ELP-IgMFc, respectively) for enhancing protein expression, bio-function and purification of H5TG. These H5TG fragments have been attached to expression cassettes in the pCB301 shuttle vector, transiently expressed in Nicotiana benthamiana by agroinfiltration, then the protein expression was confirmed by SDS-PAGE and Western blot analysis. The results showed that the expression level of the H5TGpII-ELP-IgMFc protein in plant raw extract was stronger than that of two other proteins analyzed in this paper. Evaluation of bio-function showed that the haemagglutination titre (HA titre) of the total solution protein extract containing H5TGpII-IgMFc protein was highest (64 HAU) compared to that containing two remaining proteins (8 HAU). Subsequently, the H5TGpII and H5TGpII-IgMFc proteins were purified by immobilized metal ion affinity chromatography (IMAC), while the H5TGpII-ELP-IgMFc protein was purified using membrane-based Inverse Transition Cycling (mITC). The oligomer state of the purified proteins was then determined by non-reducing SDS-PAGE. The haemagglutination assay analysis of purified proteins showed that the lowest protein amount causing erythrocyte agglutination (1 HAU) of the H5TGpII-IgMFc protein was 0.06 µg and lower four times than that of H5TGpII and H5TGpII-ELP-IgMFc proteins (both of them were 0.24 µg). This indicates that the fusing of the GCN4pII-IgMFc motif into the H5TG protein gives the stronger bio-function than the fusing of two remaining motifs into this protein. This result opens up the applicability of the IgMFc for generation of oligomer proteins to enhance the bio-function of target proteins in the study of recombinant vaccine production.

Evaluation of Strategies for Decreasing Blood Glucose Using Albuminbinding Domain

Objective: Frequent administrations for DPPIV-resistant GLP-1 analogs are necessary to maintain the blood concentrations due to the short half-life of less than 5 minutes. However, most delivery systems that possess the ability of sustainable release of GLP-1 have drawbacks such as low yield, high cost and undesirable side effects. Therefore, we aimed to prepare a simple and efficient delivery system that could be feasibly applied to reduce blood glucose. Methods: A novel GLP-1 delivery system (GLP-1-ELPs-SA) was prepared and characterized by circular dichroism. Furthermore, the activity and property of GLP-1-ELPs-SA were evaluated in vitro and in vivo. Results: GLP-1-ELPs-SA are easily expressed in E. coli in a soluble formulation and purified through the inverse transition cycle. GLP-1-ELPs-SA spontaneously generated depot under physiological conditions. GLP-1-ELPs-SA was also found to be dispersed in the blood vessels from the depot and showed a high affinity to bind with mice (C57BL/6J) albumin, which shows that GLP-1-ELPs-SA has a long circulation time in vivo. Conclusions: Our delivery system could markedly decrease the clearance of recombinant proteins based on serum albumin, without substantially increasing the protein molecular weight and remarkably reducing the blood glucose within 120 h.

Finite element based Monte Carlo simulation of options on Lévy driven assets

This paper extends the simulation algorithm by Andreasen and Huge (2011) to the simulation of option prices and deltas on Lévy driven assets where the simulation is performed relying on the inverse transition matrix of the discretized partial integro differential equation (PIDE). We demonstrate how one can get accurate prices and deltas of European options on VG and CGMY via Monte Carlo simulations.

RESEARCH OF TEMPERATURE PROFILES IN THE WELL IN THE COURSE OF PUMPING LIQUID ON THE BASIS OF NUMERICAL INVERSION OF ISEGER

The analysis of a temperature profile in the trunk of a vertical well when pumping liquid was carried out. The paper describes the application of an algorithm of the inverse numerical transformation with use of Gaussian quadratures (Iseger's method) to a task about a temperature profile under conditions of a short-term liquid pumping into the well. Analytical dependences are constructed on the basis of a method of the Laplace-Carson integral transformation of decomposition. The inverse transition is carried out on the basis of numerical inversion with use of Gaussian quadratures (Iseger's method).