scholarly journals The Catalytic Activity and Penicillin Sensitivity in the Liquid and Frozen States of Membrane-Bound and Detergent-Solubilised Transpeptidase of Streptomyces R61

1975 ◽  
Vol 56 (1) ◽  
pp. 57-65 ◽  
Author(s):  
Jean DUSART ◽  
Jean-Marie GHUYSEN ◽  
Alberto MARQUET ◽  
Harold R. PERKINS
Keyword(s):  
Catalytic Activity ◽  
Membrane Bound

Copper and nickel uptake and accumulation, and their effects on redox and electrical potentials of hepatopancreatic cells of Oniscus asellus Linnaeus (Porcellionidae, Isopoda)

1990 ◽  
Vol 68 (4) ◽  
pp. 651-655 ◽  
Author(s):  
M. A. Alikhan ◽  
V. Storch
Keyword(s):  
Catalytic Activity ◽  
Cell Membrane ◽  
Membrane Surface ◽  
Dry Weight ◽  
Body Tissue ◽  
Electrical Potentials ◽  
Nickel Uptake ◽  
Membrane Bound ◽  
Total Body ◽  
Cell Membrane Surface

Highest tissue Cu concentrations (1728 μg∙g dry weight−1) in whole Oniscus asellus, reared for 7 days on carrot powder containing 50 μg Cu∙g dry weight−1, 10 μg Ni∙g dry weight−1, or a mixture of 50 μg Cu and 10 μg Ni∙g dry weight−1, were observed in isopods on 50 μg Cu∙g dry weight−1, and lowest (917 μg∙g dry weight−1) in those on 10 μg Ni∙g dry weight−1. Highest Ni concentrations (277 and 272 μg∙g dry weight−1) were present in isopods fed on a mixture of 50 μg Cu and 10 μg Ni∙g dry weight−1 and 10 μg Ni∙g dry weight−1, respectively, and lowest (201 μg∙g dry weight−1) in those on 50 μg Cu∙g dry weight−1. Of the total body-tissue Cu, 8–66% was contained in membrane-bound vesicles of hepatopancreatic S-cells, and 73–89% of Ni was present inside the lumen and within S-cells of the hepatopancreas. The presence of Ni in the diet appeared to adversely affect the absorption and hepatopancreatic storage of Cu. Copper slightly enhanced, and nickel drastically reduced, the hepatopancreatic redox (= catalytic activity) and cell-membrane surface potentials. The significance of these findings is discussed.

The catalytic activity of soluble and membrane-bound succinate dehydrogenase

FEBS Letters ◽  
1977 ◽  
Vol 73 (2) ◽  
pp. 235-238 ◽  
Author(s):  
A.D. Vinogradov ◽  
V.G. Goloveshkina ◽  
E.V. Gavrikova
Keyword(s):  
Catalytic Activity ◽  
Succinate Dehydrogenase ◽  
Membrane Bound

Determinants of the enzymatic activity and the subcellular localization of aspartate N-acetyltransferase

2011 ◽  
Vol 441 (1) ◽  
pp. 105-112 ◽  
Author(s):  
Gaëlle Tahay ◽  
Elsa Wiame ◽  
Donatienne Tyteca ◽  
Pierre J. Courtoy ◽  
Emile Van Schaftingen
Keyword(s):  
Catalytic Activity ◽  
Subcellular Localization ◽  
Fluorescent Protein ◽  
Catalytic Domain ◽  
Kinetic Properties ◽  
Conserved Residues ◽  
Membrane Bound ◽  
Green Fluorescent ◽  
Necessary And Sufficient ◽  
Membrane Region

Aspartate N-acetyltransferase (NAT8L, N-acetyltransferase 8-like), the enzyme that synthesizes N-acetylaspartate, is membrane-bound and is at least partially associated with the ER (endoplasmic reticulum). The aim of the present study was to determine which regions of the protein are important for its catalytic activity and its subcellular localization. Transfection of truncated forms of NAT8L into HEK (human embryonic kidney)-293T cells indicated that the 68 N-terminal residues (regions 1 and 2) have no importance for the catalytic activity and the subcellular localization of this enzyme, which was exclusively associated with the ER. Mutation of conserved residues that precede (Arg81 and Glu101, in region 3) or follow (Asp168 and Arg220, in region 5) the putative membrane region (region 4) markedly affected the kinetic properties, suggesting that regions 3 and 5 form the catalytic domain and that the membrane region has a loop structure. Evidence is provided for the membrane region comprising α-helices and the catalytic site being cytosolic. Transfection of chimaeric proteins in which GFP (green fluorescent protein) was fused to different regions of NAT8L indicated that the membrane region (region 4) is necessary and sufficient to target NAT8L to the ER. Thus NAT8L is targeted to the ER membrane by a hydrophobic loop that connects two regions of the catalytic domain.

Catalytic activity of the membrane-bound methylcholanthrene-inducible cytochrome P-450

FEBS Letters ◽  
1985 ◽  
Vol 179 (1) ◽  
pp. 74-76 ◽  
Author(s):  
A.Yu. Grishanova ◽  
V.M. Mishin ◽  
V.V. Lyakhovich
Keyword(s):  
Catalytic Activity ◽  
Membrane Bound ◽  
Cytochrome P 450

scholarly journals Can the lack of fibrillar form of alpha-synuclein in Lewy bodies be explained by its catalytic activity?

2021 ◽  
Author(s):  
Ivan A. Kuznetsov ◽  
Andrey V. Kuznetsov
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Catalytic Activity ◽  
Lewy Bodies ◽  
Sensitivity Study ◽  
Alpha Synuclein ◽  
Therapeutic Interventions ◽  
Model Parameters ◽  
Lewy Pathology ◽  
Membrane Bound

Finding the causative pathophysiological mechanisms for Parkinson's disease (PD) is important for developing therapeutic interventions. Until recently, it was believed that Lewy bodies (LBs), the hallmark of PD, are mostly composed of alpha-synuclein (α-syn) fibrils. Recent results (Shahmoradian et al., Lewy pathology in Parkinson's disease consists of crowded organelles and lipid membranes, Nature Neuroscience 22 (2019) 1099-1109) demonstrated that the fibrillar form of α-syn is lacking from LBs. Here we propose that this surprising observation can be explained by the catalytic activity of the fibrillar form of α-syn. We assumed that α-syn fibrils catalyze the formation of LBs, but do not become part of them. We developed a mathematical model based on this hypothesis. By using the developed model, we investigated the consequences of this hypothesis. In particular, the model suggests that the long incubation time of PD can be explained by a two-step aggregation process that leads to its development: (i) aggregation of monomeric α-syn into α-syn oligomers and fibrils and (ii) clustering of membrane-bound organelles, which may cause disruption of axonal trafficking and lead to neuron starvation and death. The model shows that decreasing the rate of destruction of α-syn aggregates in somatic lysosomes accelerates the formation of LBs. Another consequence of the model is the prediction that removing α-syn aggregates from the brain after the aggregation of membrane-bound organelles into LBs has started may not stop the progression of PD because LB formation is an autocatalytic process; hence, the formation of LBs will be catalyzed by aggregates of membrane-bound organelles even in the absence of α-syn aggregates. The performed sensitivity study made it possible to establish the hierarchy of model parameters with respect to their effect on the formation of vesicle aggregates in the soma.

Molecular cloning and catalytic activity of a membrane-bound prenyl diphosphate phosphatase from Croton stellatopilosus Ohba

2013 ◽  
Vol 91 ◽  
pp. 140-147 ◽  
Author(s):  
Natsajee Nualkaew ◽  
Nils Guennewich ◽  
Karin Springob ◽  
Anuwatchakit Klamrak ◽  
Wanchai De-Eknamkul ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Molecular Cloning ◽  
Membrane Bound ◽  
Prenyl Diphosphate

scholarly journals Membrane-Bound Fructose 1, 6-Bisphosphate Aldolase: Catalytic Activity and Mechanisms of Desorption

1980 ◽  
Vol 130 (2) ◽  
pp. 143-152 ◽  
Author(s):  
KUNIO NAKASHIMA ◽  
MACHIKO OHTSUKI ◽  
SYOZO TUBOI
Keyword(s):  
Catalytic Activity ◽  
Membrane Bound

Mechanism of action of Zn2+ and Mg2+ on rat placenta alkaline phosphatase. II. Studies on membrane-bound phosphatase in tissue sections and in whole placenta

1977 ◽  
Vol 55 (4) ◽  
pp. 474-478 ◽  
Author(s):  
Claude PetitClerc ◽  
Claude Fecteau
Keyword(s):  
Alkaline Phosphatase ◽  
Catalytic Activity ◽  
Active Sites ◽  
Maternal Serum ◽  
Alkaline Ph ◽  
Total Recovery ◽  
Tissue Sections ◽  
Trophoblastic Cells ◽  
Membrane Bound

Alkaline phosphatase (EC 3.1.3.1) bound to trophoblastic cells in rat placenta is activated by Mg2+ and inhibited by Zn2+ in the same way as is found with partially purified soluble alkaline phosphatase in the same tissue (PetitClerc, C., Delisle, M., Martel, M., Fecteau, C. &Brière, N. (1975) Can. J. Biochem. 53, 1089–1100). In studies done with tissue sections (6–10 μm), it is shown that alkaline phosphatase activity and labelling of active sites by orthophosphate are lost during incubation with ethanolamine at pH 9.0. Addition of Mg2+ causes total recovery of catalytic activity and active sites labelling. Zn2+ displaces and replaces at the Mg2+ binding sites. The affinity for both ions is similar, and dissociation of Zn2+ from the enzyme is a very slow process, even in the presence of Mg2+. The Zn2+–alkaline phosphatase and Mg2+–alkaline phosphatase, which only differ by the ion bound to an apparent modulator site, have the same catalytic activity at pH <7.0, but the Zn2+ species has little activity at alkaline pH. Phosphorylation of the enzyme by orthophosphate indicates that with both enzyme species phosphoryl intermediate does not accumulate at alkaline pH. These results suggest that with orthophosphate, the phosphorylation step is rate determining for both enzymes, and that Zn2+ affects this step to a much greater extent. It is proposed that Zn2+ and Mg2+ regulate alkaline phosphatase in rat placenta. The concentration of both ions in maternal serum and placenta suggest that such a mechanism could exist in vivo.

Sign in / Sign up

Export Citation Format

Share Document