Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C1832588 (PSS)
 2,979 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Whereas mammalian cells produce PS by a base exchange reaction from preexisting phospholipids, yeast cells synthesize PS from CDP-diacylglycerol and serine by the PS synthase reaction. Yeast PS synthase was purified to homogeneity and shown to have a molecular mass of 23 kDa. The activity is dependent on either Mg2+ or Mn2+ and Triton X-100. The enzyme specifically transfers the phosphatidyl group from CDP-diacylglycerol or dCDP-diacylglycerol to L-serine, but not to threonine, cysteine and ethanolamine. The PSS/CHO1 gene encoding the enzyme was cloned by the complementation of the choline auxotrophic pss/cho1 mutant. The deduced protein comprises 279 amino acids with a calculated molecular mass of 30,804. The primary translate undergoes proteolytic processing to the enzymatically more active 23-kDa enzyme. The deduced amino acid sequence contains several putative membrane-spanning regions and resembles that of the Bacillus subtilis enzyme, but not those of the E. coli and Haemophilus influenzae enzymes. The sequence also contains the local, conserved region found in enzymes catalyzing the transfer of the phosphoalcohol moiety from CDP-alcohol, such as PI synthase, cholinephosphotransferase and phosphatidylglycerolphosphate synthase. The activity of PS synthase is maximal in the exponential phase, but decreases when cells enter the stationary phase. The enzyme is phosphorylated at a single serine residue by cyclic AMP-dependent protein kinase with a 60-70% decrease in enzymatic activity, but the primary translation product is not phosphorylated. PS synthase is inhibited by CTP, probably due to the chelation of the divalent cations, Mg2+ and Mn2+, and also by sphingoid bases, such as sphinganine and phytosphingosine. Phosphatidate, phosphatidylcholine and phosphatidylinositol are stimulatory, whereas cardiolipin and diacylglycerol are inhibitory. The expression of yeast PS synthase is transcriptionally repressed by myo-inositol and choline in a coordinate manner with other phospholipid-synthesizing enzymes. The upstream regulatory region of the PSS/CHO1 gene responsible for the myo-inositol-choline regulation was identified. An octameric sequence, CATRTGAA (R = A or G), plays an important role in the conferral of the myo-inositol-choline transcriptional regulation.
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PMID:Phosphatidylserine synthase from yeast. 937 Mar 37

Using A10B single-chain fragment variable (scFv) as a model system, we demonstrated that the flexibility of scFv linker engineering can be combined with the inherent quick and adaptable characters of surface coupling chemistry (e.g., electrostatic, hydrogen bonding, or covalent attachment) to attach scFv to preformed functionalized self-assembled monolayers (SAMs). Six arginines, which were separated by glycine or serine as spacer, were incorporated in the peptide linker to form a 15-mer peptide linker (RGRGRGRGRSRGGGS). The polycationic arginine peptide was engineered into the A10B scFv-RG3 to favor its adsorption at anionic charged template surface (11-mercaptoundecanoic acid (MUA) and poly(sodium 4-styrenesulfonate (PSS))). This new approach was compared with the other engineered scFv constructs. Our results demonstrated that the anionic charged SAM template facilitated the oriented immobilization of scFvs on the SAM template surface as well as reduced the possibility of protein denaturation when directly immobilized on the solid surface. A 42-fold improvement of detection limits using MUA/A10B scFv-RG3 (less than 0.2 nM experimentally determined) was achieved compared to A10B Fab antibody and a 5-fold improvement was observed compared to A10B scFv that was engineered with a cysteine in the linker sequence. Using protein A-coated gold nanoparticles, a picomolar experimental detection limit was achieved. With 20 amino acids to choose from, engineered recombinant scFv in combination with SAM technology and nanoparticle mass amplification provide an emerging strategy for the development of highly sensitive and specific scFv immunosensors.
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PMID:Engineering peptide linkers for scFv immunosensors. 1829 Jun 68

Electrochemical impedance spectroscopy and the quartz crystal microbalance are used to monitor the deposition of polyelectrolytes onto an interface modified with a monolayer of cysteine. When using an anionic redox probe, Fe(CN)(6)(-4), the impedance of the cysteine modified electrode is a function of the solution pH; the charge-transfer resistance being higher at basic pH, and smaller under acidic conditions relative to the value found when the solution is buffered near the pI for cysteine. This behavior is consistent with the electrostatic interaction between the anionic redox probe and the net charge of the interface. After exposure of the cysteine-modified interface to 0.10 mol L(-1) HCl solutions containing polystyrene sulfonate, the impedance of the modified interface increases. This behavior is consistent with the interface having a net negative charge, and suggests that the polyanion is confined to the interface. Quartz crystal microbalance measurements also show that 700+/-20 ng of the PSS is deposited under the acidic conditions. After exposure to 0.10 mol L(-1) NaOH solutions containing poly(diallyldimethyl)ammonium chloride, the impedance of the modified interface decreases, consistent with the electrostatic assembly of the polycation to the cysteine monolayer under these conditions. Quartz crystal microbalance measurements indicate that 770+/-40 ng of the poly(diallyldimethylammonium chloride) are deposited under the basic conditions.
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PMID:Electrostatic deposition of polycations and polyanions onto cysteine monolayers. 1910 47

Free radicals that form from reactive species of nitrogen and oxygen can react dangerously with cellular components and are involved with the pathogenesis of diabetes, cancer, Parkinson's, and heart disease. Cysteine amino acids, due to their reactive nature, are prone to oxidation by these free radicals. Determining which cysteines oxidize within proteins is crucial to our understanding of these chronic diseases. Wet lab techniques, like differential alkylation, to determine which cysteines oxidize are often expensive and time-consuming. We utilize machine learning as a fast and inexpensive approach to identifying cysteines with oxidative capabilities. We created the original features RAMmod and RAMseq for use in classification. We also incorporated well-known features such as PROPKA, SASA, PSS, and PSSM. Our algorithm requires only the protein sequence to operate; however, we do use template matching by MODELLER to acquire 3D coordinates for additional feature extraction. There was a mean improvement of RAM over N6C by 22.04% MCC. It was statistically significant with a p-value of 0.015. RAM provided a significant increase over PSSM with a p-value of 0.040 and an average 70.09% improvement MCC.
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PMID:Residue Adjacency Matrix Based Feature Engineering for Predicting Cysteine Reactivity in Proteins. 3067 Nov 96