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Phosphate Residue (phosphate + residue)
Selected AbstractsAn assay system for the detection of phospholipase C activityEUROPEAN JOURNAL OF LIPID SCIENCE AND TECHNOLOGY, Issue 10 2003Markus Durban Abstract Phospholipase C (PLC, EC 3.1.4.3) enzymes specifically hydrolyze the C-O-P-bond in phospholipids, yielding sn -1, 2(2, 3)-diglycerides and a phosphate residue bearing the corresponding head group. Biochemical characterization of PLC requires methods for determination of activity. During characterization and purification, proteins are separated by polyacrylamide gel electrophoresis (PAGE). For direct identification and visualization of PLC, a new assay for activity staining in native and renatured SDS-PAGE is described. Incubation of a gel containing an active PLC in the presence of ,-naphthylphosphorylcholine leads to ,-naphthol formation. This reacts with the diazonium salt Fast Red, forming a red dye which allows clear determination of PLC purity, molecular weight and substrate specificity. The assay was verified using commercially available PC-PLC and new PC-PLC-producing Bacillus cereus strains. The substrate ,-NPC was prepared by chemical synthesis at an overall yield of 12%. [source] Protein Hydrolysate of Salted Duck Egg White as a Substitute of Phosphate and Its Effect on Quality of Pacific White Shrimp (Litopenaeus Vannamei)JOURNAL OF FOOD SCIENCE, Issue 8 2009Thammarat Kaewmanee ABSTRACT:, Protein hydrolysate from salted egg white (PHSEW) with different degrees of hydrolysis (DH) (3%, 6%, and 9%) was produced using pepsin. Disappearance of proteins with molecular weight (MW) of 108 and 85 kDa with the concomitant formation of proteins with MW of 23, 20, 13, and 5 kDa was observed in PHSEW. The use of PHSEW for quality improvement of Pacific white shrimp (Litopenaeus vannamei) was investigated. Shrimp soaked in 4% NaCl containing 7% PHSEW and 2.5% mixed phosphates (0.625% sodium acid pyrophosphate [SAPP] and 1.875% tetrasodium pyrophosphate [TSPP]) had the highest cooking yield with the lowest cooking loss (P,< 0.05), compared with shrimps with other treatments. Nevertheless, no difference in weight gain was obtained in comparison with those treated with 4% NaCl containing 3.5% mixed phosphate (P,> 0.05). Cooked shrimp treated with 4% NaCl containing 7% PHSEW and 2.5% mixed phosphate or those treated with 4% NaCl containing 3.5% mixed phosphate had the higher score of appearance, texture, and overall likeness but less shear force, in comparison with the control (no treatment) (P,< 0.05). Microstructure study revealed that muscle fibers of cooked shrimp from both treatments had the swollen fibrils and gaps, while the control had the swollen compact structure. Therefore, use of PHSEW could reduce phosphate residue in shrimps without an adverse effect on sensory properties. [source] Novel diadenosine polyphosphate analogs with oxymethylene bridges replacing oxygen in the polyphosphate chainFEBS JOURNAL, Issue 6 2009Potential substrates and/or inhibitors of Ap4A hydrolases Dinucleoside polyphosphates (NpnN,s; where N and N, are nucleosides and n = 3,6 phosphate residues) are naturally occurring compounds that may act as signaling molecules. One of the most successful approaches to understand their biological functions has been through the use of NpnN, analogs. Here, we present the results of studies using novel diadenosine polyphosphate analogs, with an oxymethylene group replacing one or two bridging oxygen(s) in the polyphosphate chain. These have been tested as potential substrates and/or inhibitors of the symmetrically acting Ap4A hydrolase [bis(5,-nucleosyl)-tetraphosphatase (symmetrical); EC 3.6.1.41] from E. coli and of two asymmetrically acting Ap4A hydrolases [bis(5,-nucleosyl)-tetraphosphatase (asymmetrical); EC 3.6.1.17] from humans and narrow-leaved lupin. The six chemically synthesized analogs were: ApCH2OpOCH2pA (1), ApOCH2pCH2OpA (2), ApOpCH2OpOpA (3), ApCH2OpOpOCH2pA (4), ApOCH2pOpCH2OpA (5) and ApOpOCH2pCH2OpOpA (6). The eukaryotic asymmetrical Ap4A hydrolases degrade two compounds, 3 and 5, as anticipated in their design. Analog 3 was cleaved to AMP (pA) and ,,,-methyleneoxy-ATP (pOCH2pOpA), whereas hydrolysis of analog 5 gave two molecules of ,,,-oxymethylene ADP (pCH2OpA). The relative rates of hydrolysis of these analogs were estimated. Some of the novel nucleotides were moderately good inhibitors of the asymmetrical hydrolases, having Ki values within the range of the Km for Ap4A. By contrast, none of the six analogs were good substrates or inhibitors of the bacterial symmetrical Ap4A hydrolase. [source] Discovery, regulation, and action of the major apoptotic nucleases DFF40/CAD and endonuclease GJOURNAL OF CELLULAR BIOCHEMISTRY, Issue 6 2005Piotr Widlak Abstract Toward the end of the 20th and beginning of the 21st centuries, clever in vitro biochemical complementation experiments and genetic screens from the laboratories of Xiaodong Wang, Shigekazu Nagata, and Ding Xue led to the discovery of two major apoptotic nucleases, termed DNA fragmentation factor (DFF) or caspase-activated DNase (CAD) and endonuclease G (Endo G). Both endonucleases attack chromatin to yield 3,-hydroxyl groups and 5,-phosphate residues, first at the level of 50,300 kb cleavage products and next at the level of internucleosomal DNA fragmentation, but these nucleases possess completely different cellular locations in normal cells and are regulated in vastly different ways. In non-apoptotic cells, DFF exists in the nucleus as a heterodimer, composed of a 45 kD chaperone and inhibitor subunit (DFF45) [also called inhibitor of CAD (ICAD-L)] and a 40 kD latent nuclease subunit (DFF40/CAD). Apoptotic activation of caspase-3 or -7 results in the cleavage of DFF45/ICAD and release of active DFF40/CAD nuclease. DFF40's nuclease activity is further activated by specific chromosomal proteins, such as histone H1, HMGB1/2, and topoisomerase II. DFF is regulated by multiple pre- and post-activation fail-safe steps, which include the requirements for DFF45/ICAD, Hsp70, and Hsp40 proteins to mediate appropriate folding during translation to generate a potentially activatable nuclease, and the synthesis in stoichiometric excess of the inhibitors (DFF45/35; ICAD-S/L). By contrast, Endo G resides in the mitochondrial intermembrane space in normal cells, and is released into the nucleus upon apoptotic disruption of mitochondrial membrane permeability in association with co-activators such as apoptosis-inducing factor (AIF). Understanding further regulatory check-points involved in safeguarding non-apoptotic cells against accidental activation of these nucleases remain as future challenges, as well as designing ways to selectively activate these nucleases in tumor cells. © 2005 Wiley-Liss, Inc. [source] | |||||||||||||