Preparation of Potent Cytotoxic Ribonucleases by Cationization:  Enhanced Cellular Uptake and Decreased Interaction with Ribonuclease Inhibitor by Chemical Modification of Carboxyl Groups†

Biochemistry ◽  
2001 ◽  
Vol 40 (25) ◽  
pp. 7518-7524 ◽  
Author(s):  
Junichiro Futami ◽  
Takashi Maeda ◽  
Midori Kitazoe ◽  
Emiko Nukui ◽  
Hiroko Tada ◽  
...  
Keyword(s):  
Chemical Modification ◽  
Cellular Uptake ◽  
Carboxyl Groups ◽  
Ribonuclease Inhibitor ◽  
Cytotoxic Ribonucleases

scholarly journals Endocytotic Internalization as a Crucial Factor for the Cytotoxicity of Ribonucleases

2007 ◽  
Vol 282 (38) ◽  
pp. 27640-27646 ◽  
Author(s):  
Franziska Leich ◽  
Nadine Stöhr ◽  
Anne Rietz ◽  
Renate Ulbrich-Hofmann ◽  
Ulrich Arnold
Keyword(s):  
Catalytic Activity ◽  
Cellular Uptake ◽  
Cellular Membrane ◽  
Subcellular Fractionation ◽  
Rnase A ◽  
Cytotoxic Action ◽  
Ribonuclease Inhibitor ◽  
Proteolytic Stability ◽  
K 562 Cells

The cytotoxic action of ribonucleases (RNases) requires the interaction of the enzyme with the cellular membrane, its internalization, translocation to the cytosol, and the degradation of ribonucleic acid. The interplay of these processes as well as the role of the thermodynamic and proteolytic stability, the catalytic activity, and the evasion from the intracellular ribonuclease inhibitor (RI) has not yet been fully elucidated. As cytosolic internalization is indispensable for the cytotoxicity of extracellular ribonucleases, we investigated the extent of cytosolic internalization of a cytotoxic, RI-evasive RNase A variant (G88R-RNase A) and of various similarly cytotoxic but RI-sensitive RNase A tandem enzyme variants in comparison to the internalization of the non-cytotoxic and RI-sensitive RNase A. After incubation of K-562 cells with the RNase A variants for 36 h, the internalized amount of RNases was analyzed by rapid cell disruption followed by subcellular fractionation and semiquantitative immunoblotting. The data indicate that an enhanced cellular uptake and an increased entry of the RNases into the cytosol can outweigh the abolishment of catalytic activity by RI. As all RNase A variants proved to be resistant to the proteases present in the different subcellular fractions for more than 100 h, our results suggest that the cytotoxic potency of RNases is determined by an efficient internalization into the cytosol.

Effect of Lectins and Chemical Modification on the Hemagglutinin Activity of Human Plasma Fibronectin

1981 ◽  
Vol 36 (9-10) ◽  
pp. 863-868 ◽  
Author(s):  
Matti Vuento ◽  
Eija Salonen
Keyword(s):  
Chemical Modification ◽  
Human Plasma ◽  
Present Report ◽  
Red Cells ◽  
Carboxyl Groups ◽  
Plasma Fibronectin ◽  
Cell Surfaces ◽  
Serum Factors ◽  
Low Concentrations ◽  
Erythrocyte Surface

Abstract Purified hum an plasm a fibronectin has been shown to agglutinate protease-treated red cells [Vuento, Hoppe-Seyler's Z. Physiol. Chem. 360, 1327-1333, (1979)]. The present report shows that the activity is inhibited by low concentrations of lectins and by macrom olecular serum factors. Chemical m odification of carboxyl groups of fibronectin strongly inhibited the activity, but modification of am ino groups or guanidinium groups had little effect on the activity. The results suggest that fibronectin receptors on erythrocyte surface are carbohydrate-containing molecules. Humoral m acrom olecular factors may control the interaction of fibronectin with cell surfaces. Chemical m odification studies indicate that the parts of the fibronectin molecule responsible for the hem agglutinin activity are different from those mediating the binding of fibronectin to collagen.

Chemical modification of carboxyl groups in human Fcγ fragment: Structural role and effect on the complement fixation

1980 ◽  
Vol 17 (3) ◽  
pp. 327-336 ◽  
Author(s):  
F. Vivanco-Martínez ◽  
R. Bragado ◽  
J.P. Albar ◽  
C. Juarez ◽  
F. Ortíz-Masllorens
Keyword(s):  
Chemical Modification ◽  
Complement Fixation ◽  
Carboxyl Groups ◽  
Structural Role

Study on a Photonic Crystal Hydrogel Material for Chemical Sensing

2015 ◽  
Vol 14 (01n02) ◽  
pp. 1460025
Author(s):  
Jia-Yu Xu ◽  
Chun-Xiao Yan ◽  
Xiao-Chun Hu ◽  
Chao Liu ◽  
Hua-Min Tang ◽  
...  
Keyword(s):  
Photonic Crystal ◽  
Ionic Strength ◽  
Chemical Modification ◽  
Chemical Sensing ◽  
Electrostatic Interactions ◽  
Carboxyl Groups ◽  
Polystyrene Spheres ◽  
Crystalline Colloidal Arrays ◽  
Crystalline Colloidal Array ◽  
Monodisperse Polystyrene

There is intense interest in the applications of photonic crystal hydrogel materials for the detection of glucose, metal ions, organophosphates and so on. In this paper, monodisperse polystyrene spheres with diameters between 100 ~ 440 nm were synthesized by emulsion polymerization. Highly charged polystyrene spheres readily self-assembled into crystalline colloidal array because of electrostatic interactions. Photonic crystal hydrogel materials were formed by polymerization of acrylamide hydrogel around the crystalline colloidal arrays of polystyrene spheres. After chemical modification of hydrogel backbone with carboxyl groups, our photonic crystals hydrogel materials are demonstrated to be excellent in response to pH and ionic strength changes.

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