Topic
Alkaline phosphatase
About: Alkaline phosphatase is a research topic. Over the lifetime, 20218 publications have been published within this topic receiving 540547 citations. The topic is also known as: Alkaline_phosphatase & IPR001952.
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TL;DR: The cysteines of the Escherichia coli periplasmic enzyme alkaline phosphatase were found to be fully reduced when the protein was retained in the cytoplasm, which contrasted with the normally exported protein, wherein disulfide bonds formed rapidly.
Abstract: The cysteines of the Escherichia coli periplasmic enzyme alkaline phosphatase, which are involved in disulfide bonds in the native enzyme, were found to be fully reduced when the protein was retained in the cytoplasm. Under these circumstances the cysteines remained reduced for at least several minutes after the synthesis of the protein was completed. This contrasted with the normally exported protein, wherein disulfide bonds formed rapidly. Disulfide bond formation accompanied export and processing. The implications of these findings for the inactivity of the enzyme in the cytoplasm are discussed. Images
212 citations
TL;DR: By destabilizing the membranes of P. aeruginosa, gentamicin increases the release of membrane vesicles three- to five-fold, which may help account for some of the bacterium-mediated toxicity encountered during patient treatment with aminoglycoside antibiotics.
Abstract: Pseudomonas aeruginosa (and various other gram-negative pathogens) liberate membrane vesicles during normal growth. These bilayered vesicles consist of endotoxin (lipopolysaccharide), outer membrane proteins and several potent hydrolytic enzymes including protease, alkaline phosphatase, phospholipase C and peptidoglycan hydrolase. The vesicles contain pro-elastase and alkaline phosphatase (which are periplasmic constituents) and so are important for packaging periplasmic components as they are liberated to the outside of the cell. Once liberated, the vesicles are capable of fusing with the membranes of epithelial cells and liberating their virulence factors into host cells where they degrade cellular components, thereby aiding infection by the pathogen. The aminoglycoside antibiotic, gentamicin, is thought to kill bacteria by inhibiting protein synthesis, yet this cationic antibiotic can also perturb the packing order of lipids, thereby destabilizing bilayered membranes. For pathogens with highly anionic lipopolysaccharide on their surface, such as P. aeruginosa, this membrane destabilization can be so serious that it can cause cell lysis; these cells are therefore killed by a combination of protein synthesis inhibition and surface perturbation. By destabilizing the membranes of P. aeruginosa, gentamicin increases the release of membrane vesicles three- to five-fold. This may help account for some of the bacterium-mediated toxicity encountered during patient treatment with aminoglycoside antibiotics.
211 citations
TL;DR: The different effects of cytokines on TNAP activity and collagen expression may help explain why inflammation decreases bone formation in RA whereas it induces ectopic ossification from collagen-rich entheses during SpAs.
210 citations
TL;DR: Differences in behavior between PDL cells and gingival fibroblasts may prove important in designing appropriate clinical therapies directed at stimulating periodontal regeneration.
Abstract: A primary objective in the treatment of periodontal diseases is the regeneration of the mineralized and soft connective tissue components of the attachment apparatus. Current theories suggest the cells of the periodontium have the capacity, when appropriately triggered, to actively participate in restoring connective tissues, including mineralized tissues. To evaluate further the role of such cells in periodontal homeostasis, periodontal ligament (PDL) cells and gingival fibroblasts (GF) were cultured and examined for alkaline phosphatase levels and for the ability to produce mineralized nodules in culture. These are two characteristics of osteoblast-like cells in vitro. The levels of alkaline phosphatase produced by these cells were determined by a modified kinetic assay and the ability of these cells to produce mineral-like nodules in vitro was evaluated by Von Kossa staining and light and electron microscopy. PDL cells had significantly higher levels of alkaline phosphatase when compared with gingival fibroblasts obtained from the same patient and the same passage, in vitro. Furthermore PDL cells, but not GF, were capable of producing mineral-like nodules in vitro. These results indicate differences in behavior between PDL cells and GF; such differences may prove important in designing appropriate clinical therapies directed at stimulating periodontal regeneration.
210 citations
TL;DR: MS‐based proteomics can reveal novel markers for MSCs that can be used for their isolation and for monitoring OB differentiation, and no concordance was detected between the changes in levels of gene and protein expression during OB differentiation.
Abstract: One of the major limitations for understanding the biology of human mesenchymal stem cells (hMSCs) is the absence of prospective markers needed for distinguishing them from other cells and for monitoring lineage-specific differentiation. Mass spectrometry (MS)-based proteomics has proven extremely useful for analyzing complex protein expression patterns and, when applied quantitatively, can be used to resolve subtle differences between samples. Thus, we used MS to characterize changes in expression of membrane protein markers before and after short-term induction of osteoblast (OB) differentiation in a cell model of hMSCs established by overexpression of human telomerase reverse-transcriptase gene. We identified 463 unique proteins with extremely high confidence, including all known markers of hMSCs (e.g., SH3 [CD71], SH2 [CD105], CD166, CD44, Thy1, CD29, and HOP26 [CD63]) among 148 integral membrane or membrane-anchored proteins and 159 membrane-associated proteins. Twenty-nine integrins and cell adhesion molecules, 20 receptors, and 18 Ras-related small GTPases were also identified. Upon OB differentiation, the expression levels of 83 proteins increased by at least twofold whereas the levels of another 21 decreased by at least twofold. For example, alkaline phosphatase (ALP), versican core protein, and tenascin increased 27-, 12-, and 4-fold, respectively, and fatty acid synthase decreased sixfold. The observed increases in veriscan and ALP were confirmed using immunocytochemistry and cytochemistry. Quantitative real-time reverse transcription-polymerase chain reaction confirmed the presence of mRNA of these membrane proteins. However, with the exception of ALP, no concordance was detected between the changes in levels of gene and protein expression during OB differentiation. In conclusion, MS-based proteomics can reveal novel markers for MSCs that can be used for their isolation and for monitoring OB differentiation.
209 citations