Structural Basis for Phospholyase Activity of a Class III Transaminase Homologue

Pyridoxal‐phosphate (PLP)‐dependent enzymes catalyse a remarkable diversity of chemical reactions in nature. A1RDF1 from Arthrobacter aurescens TC1 is a fold type I, PLP‐dependent enzyme in the class III transaminase (TA) subgroup. Despite sharing 28 % sequence identity with its closest structural homologues, including β‐alanine:pyruvate and γ‐aminobutyrate:α‐ketoglutarate TAs, A1RDF1 displayed no TA activity. Activity screening revealed that the enzyme possesses phospholyase (E.C. 4.2.3.2) activity towards O‐phosphoethanolamine (PEtN), an activity described previously for vertebrate enzymes such as human AGXT2L1, enzymes for which no structure has yet been reported. In order to shed light on the distinctive features of PLP‐dependent phospholyases, structures of A1RDF1 in complex with PLP (internal aldimine) and PLP ? PEtN (external aldimine) were determined, revealing the basis of substrate binding and the structural factors that distinguish the enzyme from class III homologues that display TA activity.     

Use and recycling of Ca-alginate biocatalyst for removal of phenol from wastewater

The objective of the current work is the exhaustive study of the phenol degradation potential in both free cell and immobilized bacterium (Pseudomonas aeruginosa) in calcium alginate beads (biocatalyst) was investigated for its ability to grow and degrade phenol as its sole source of carbon and energy.The biodegradation assays were performed in liquid medium with phenol being the only substrate. It was found that P. aeruginosa is able to degrade phenol up to 500 mg L^?1 in 50 h as free cell and 900 mg L^?1 in 80 h when immobilized in the calcium alginate beads. However, for 1200 mg L^?1 concentration, the immobilized cells took much more time (290 h) for a complete degradation.The reuse of these beads in different concentrations of phenol (100–900 mg L^?1) showed that the cells keep their phenol degradation ability up to 900 mg L^?1in 78.5 h with 99% removal efficiency.Similarly, the reuse of the biocatalyst in the same initial phenol concentration (500 mg L^?1), allows us to get 9 cycles.     

Fast mode decision algorithm for H.264/SVC enhancement layer

Scalable video coding (SVC) has been standardized to extend the capabilities of the H.264 advanced video coding (AVC). The SVC can compress several video sequences of various resolutions as a single bit-stream. In the SVC enhancement layer, for Joint Scalable Video Model (JSVM) software implementation, an exhaustive mode decision process based on the base layer mode predictions is performed to obtain the best mode for each macroblock (MB). This technique may achieve a higher coding efficiency; however, it induces a significant computational complexity in the encoding engine. In order to speedup the SVC encoder, a fast mode decision algorithm was proposed in this paper. In other words, our aim was to decrease the number of candidate modes to reduce the computational complexity and maintain the same level of coding efficiency, this approach used the spatial and temporal correlation between MB situated at the enhancement layer and its co-located MB at the base layer. Our statistical analyses were made using several HD sequences with different motion characteristics. Experimental results show a significant improvement in terms of time encoding which is a major constraint for any real-time implementation. However, this gain is accompanied with an acceptable loss in video quality and a tolerable bit rate increase for most media supports. In fact, our proposed algorithm permits a major improvement that can reach up to 64.9 % in terms of computational effort. This gain will induce an average loss yield to 10.5 or 13.87 % that is comparable to the 13.12 % of the He Li’s algorithm with an acceptable loss in terms of subjective video quality.     

"Eyewitness researchers as experts in court: responsive to change in a dynamic and rational process": Comment.

Responds to the comments by M. L. McCullough (see record 2002-12932-018) on the original article (see record 2001-17140-001) which discussed eyewitness testimony. The current author states that McCullough's commentary rests on a foundation of assumptions that were both na?ve and erroneous. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Some hydrolases in human schistosomiasis with special reference to arylsulfatase B

Among many tested enzymes, lipase was found to be the one most affected by schistosomiasis in human serum, where it is increased eightfold. Arylsulfatases A and B and aspartyl protease displayed a significant decrease in the serum, while other enzymes showed a significant increase. α‐Amylase and Leucine aminopeptidase were significantly increased and arylsulfatase B showed a significant decrease. Arylsulfatase B from a patient's leucocytes did not show either changed kinetic behaviour or temperature‐dependent conformational changes. These results indicate that the diminished activity of this enzyme may be attributed to an opposing mechanism of regulation.