Substrate entering and product leaving trajectories predict an engulfing dynamic for the major conformational change of the β-lactam acylase

It is still a major challenge to acquire insight into the conformational changes between the ground state and the transition state of an enzyme, although conformational fluctuation within interconverting conformers has been widely investigated (1-4). Here, we utilize different enzymatic reactions in b-lactam acylase to figure out the substrate/product trajectories in the enzyme, thereby probing the overall conformational changes in transition state. First, an auto-proteolytic intermediate of cephalosporin acylase (EC 3.5.1.11) with partial spacer segment was identified. As a final proteolytic step, the deletion of this spacer segment was revealed to be a first-order reaction, suggesting an intramolecular Ntn mechanism for the auto-proteolysis. Accordingly, the different proteolytic sites in the acylase precursor indicate a substrate entering pathway along the spacer peptide. Second, bromoacyl-7ACA can interact with penicillin G acylase (EC 3.5.1.11) in two distinguish aspects, to be hydrolyzed as a substrate analogue and to affinity alkylate the conserved Trpb4 as a product analogue. The kinetic correlation between these two reactions suggests a channel opening from Serb1 to Trpb4, responsible for the main product leaving. These two reaction trajectories relaying at the active centre, together with the crystal structures (5-10), predict an engulfing dynamic involving pocket constriction and channel opening

Proteomics study of serum exosomes in Kawasaki disease patients with coronary artery aneurysms

Background: To study the protein profile of the serum exosomes of patients with coronary artery aneurysms (CAA) caused by Kawasaki disease (KD). Methods: Two-dimensional electrophoresis (2-DE) was used to identify proteins from the exosomes of serum obtained from children with CAA caused by KD, as well as healthy controls. Differentially expressed proteins were identified using matrix-assisted laser desorption/ionization time-of-flight/timeof-flight mass spectrometry (MALDI-TOF/TOF MS) analysis. Results: Thirty two differentially expressed proteins were identified (18 up-regulated and 14 downregulated) from serum exosomes of children with CAA and were compared to healthy controls. The expression levels of 4 proteins (TN, RBP4, LRG1, and APOA4) were validated using Western blotting. Classification analysis and protein–protein network analysis showed that they are associated with multiple functional groups, including host immune response, inflammation, apoptotic process, developmental process, and biological adhesion process. Conclusions: These findings establish a comprehensive proteomic profile of serum exosomes from children with CAA caused by KD, and provide additional insights into the mechanisms of CAA caused by KD

Geometric bionics: Lotus effect helps polystyrene nanotube films get good blood compatibility

Various biomaterials have been widely used for manufacturing biomedical applications including artificial organs, medical devices and disposable clinical apparatus, such as vascular prostheses, blood pumps, artificial kidney, artificial hearts, dialyzers and plasma separators, which could be used in contact with blood^1^. However, the research tasks of improving hemocompatibility of biomaterials have been carrying out with the development of biomedical requirements^2^. Since the interactions that lead to surface-induced thrombosis occurring at the blood-biomaterial interface become a reason of familiar current complications with grafts therapy, improvement of the blood compatibility of artificial polymer surfaces is, therefore a major issue in biomaterials science^3^. After decades of focused research, various approaches of modifying biomaterial surfaces through chemical or biochemical methods to improve their hemocompatibility were obtained^1^. In this article, we report that polystyrene nanotube films with morphology similar to the papilla on lotus leaf can be used as blood-contacted biomaterials by virtue of Lotus effect^4^. Clearly, this idea, resulting from geometric bionics that mimicking the structure design of lotus leaf, is very novel technique for preparation of hemocompatible biomaterials

The Impact of Space Delocalization and Time Delocalization on the CSR Strategy in a Transition Period ——A Case Study of Chinese Small and Medium-sized Export-oriented Apparel Firms

Since the 1990s, many Chinese small and medium-sized export-oriented firms have begun to accept higher corporate social responsibility (CSR) standards because of factory inspections. In recent years, firms have been facing greater market competition in a period of transition. Different firms have different attitudes toward CSR behavior in same external macroenvironment, and some firms have formed a CSR strategy. To further explore the issue, this paper studied the impact of space delocalization and time delocalization on the CSR strategy of Chinese small and medium-sized export-oriented firms based on social structure theory. Using the case study approach, the results showed the following: (1) space delocalization can stimulate the CSR behavior of firms, although some behaviors are the result of compromise, and CSR strategy will not be initiated because of passive CSR behavior; (2) the stimulation of space delocalization can stimulate endogenous changes, but the cultural background of time delocalization has a far-reaching impact on the formation of CSR strategy

Discovering Fuzzy Association Rules from Patient's Daily Text Messages to Diagnose Melancholia

With the constant stress from work load and daily life people may show symptoms of melancholia. However, most people are reluctant to describe it or may not know that they already have it. In this paper a novel system is proposed to discover clues from patient’s interaction with psychologist or from self-recorded voice or text messages. A user friendly interface is provided for patients to input text messages or record a voice file by mobile phones or other input devices. A speech-totext conversion software is used to convert voice mails to simple text files in advance. Based on the text files, a data mining model is used to discover frequent keywords mentioned in the text or speech files. The association rules can be used to help psychologists diagnose patients’ degree of melancholia. Experimental results show that the proposed system can effectively discover melancholia keywords