ABSTRACT
Arginine kinase (AK) is a key enzyme in energy metabolism of invertebrates and plays an important regulatory role in the life activities such as growth and development, nutrition utilization, immune resistance and stress response. Arginine kinase of Bombyx mori (BmAK) is related to the energy balance and anti-NPV process, but there is little research on its molecular structure and enzymatic properties. We cloned the ORF sequence of BmAK gene, and analyzed chromosomal localization, genomic structure, mRNA structure, secondary and tertiary structure. Phylogenetic analysis indicated that AK was highly conserved in evolution. Soluble recombinant BmAK was obtained by prokaryotic expression, and purified by Ni-NTA affinity chromatography. The circular dichroism spectroscopy showed that BmAK contained α-helix structures, and its α-helix structures were relatively stable in the pH range between 5 and 10. Enzyme activity analysis showed that the optimum temperature of BmAK was 30 ℃ and the optimum pH of BmAK was 7.5. The optimal temperature of BmAK was 25 ℃. Between 15 ℃ and 30 ℃, the structure and activity of BmAK was relatively stable. The structure of BmAK was relatively stable at pH 7.0. Our findings reveal the structure and function of BmAK to develop novel green safe and environmentally friendly insecticides.
ABSTRACT
Protein tyrosine phosphatase (PTP, EC 3.1.3.48) specifically catalyzes the removal of phosphate groups from phosphorylated tyrosine residues, resulting in protein dephosphorylation, thus regulates life activities such as cell growth, proliferation, differentiation and immunization. Protein tyrosine phosphatase h of Bombyx mori (BmPTP-h) is involved in the replication of nucleopolyhedrovirus (NPV) in Bombyx mori, but the structure and properties of BmPTP-h are little known so far. In this study, the coding sequence of BmPTP-h gene was cloned from the midgut of Bombyx mori, and its genomic structure, mRNA structure, sequence signature, secondary structure and the state in solution were analyzed. Homologous amino acid sequences alignment analysis indicated that BmPTP-h had a high similarity to PTP sequences of numbers of insect NPVs, implying that they may have a common ancestor and similar function. We constructed a prokaryotic expression vector, expressed and obtained the soluble recombinant BmPTP-h in Escherichia coli at 25 ℃, and purified BmPTP-h using Ni-NTA affinity chromatography. Gel filtration analysis showed that BmPTP-h was able to form aggregate and monomer in solution. Circular dichroism spectroscopy analysis showed that the recombinant BmPTP-h contained α-helix structure. Increasing temperature resulted in the unfolding of the α-helix structure of BmPTP-h and the decrease of the α-helix structure content of BmPTP-h. These studies provide a basis to better study the structure and regulation mechanism of BmPTP-h.
ABSTRACT
Basic helix loop helix (bHLH) transcription factor plays an important role in biological processes. Bmsage is a class of bHLH transcription factor highly expressed in the silk gland of Bombyx mori, which is not only involved in the developmental regulation of the silk gland cells at the embryonic period, but also plays a crucial regulatory role during the synthesis of silk protein. However, currently, much of the property and structure of Bmsage is still remained unknown. To study the property, structure and biological role of Bmsage, we constructed several prokaryotic expression vectors of Bmsage fused with NusA, MBP, SUMO, Trx and His tags, respectively, then screened and determined the best soluble expression vector and condition of Bmsage in Escherichia coli combining with the induction temperature and IPTG concentration, and further purified the recombinant Bmsage by Ni-column affinity chromatography according to the established expression condition and characterized its secondary structure using circular dichroism spectra. The results showed that NusA and MBP could significantly enhance the soluble expression of Bmsage in E. coli, but it was difficult to separate Bmsage from these tags. SUMO could not only increase the soluble expression of Bmsage in E. coli to a certain degree, but also be effectively separated from Bmsage. Other tags did not effectively promote the soluble expression of Bmsage in E. coli. Circular dichroism spectra showed that the purified Bmsage had well-defined α-helix structure in solution, indicating that SUMO may promote the correct folding of Bmsage into native-like structure. These work not only establish a foundation for further study of the property, structure and function of Bmsage, but also provide a reference for the expression and purification of other similar proteins.
ABSTRACT
Objective By investigating the actualities of career development potential of eight-year program medical students, to explore a direction of training mode innovation aiming to improve career development potential. Methods Eight-year program medical graduates, their tutors, and di-rectors of their clinical department in a university hospital were the subjects of the current study. Questionnaire method was applied to evaluate professional competence including clinical skills, re-search capabilities and integrative ability . Anonymous questionnaires were dispensed to eight-year program medical graduates for self-evaluation. Distinct anonymous questionnaires were dispensed to tutors directors for evaluation. Traditional doctoral graduates (professional degree or academic degree) were set as standard for comparison of specific ability of eight-year program medical students. Results 74 out of 85 (87%) questionnaires for Eight-year program medical graduates were available. 53 out of 63 (84%) questionnaires for tutors were available. 21 out of 26 (81%) questionnaires for directors of clinical departments were available. In clinical capabilities, according to 43 percent (32 persons) of the eight-year MD graduates' self-assessment and the evaluation of 94%(50 persons) mentors and 81%(17 people) department directors, eight-year program medical graduates were regarded as lower-skilled clinicians compared with doctoral graduates with professional degree . Eight-year program medical graduates were also considered with worse research capabilities than doctoral graduates with profes-sional degree by themselves (76%, n=56), their tutors (91%, n=48), and their department directors (86%, n=18). Conclusions The survey shows that to some extent, the current eight-year clinical doctoral graduates lack of career development potential, reflecting the current training mode cannot lead to the given training goals. We suggest that both clinical skills and research capabilities should be enhanced to make sure that eight-year program medical graduates deserve the title of academic physicianorphysician scientists.
ABSTRACT
Quite a few orthopedics experts have fabricated some novel bone scaffolds with nanotechnology and have carried out some researches on nano-biological effects. The study of the biological effects about nano-biomaterials can facilitate the understanding of the interaction between the biomaterials and the organism, and provide research ideas and direction to construct new biomaterials with physiological function. To better understand the interaction of nano biomaterials with protein, cells and bio-security, this review presents recent advances of biological effects about nano scaffold for bone tissue engineering.