scholarly journals Chemical modification of DNA with muta-carcinogens. II. Base sequence-specific binding to DNA of 2-amino-6-methyl-dipyrido[1,2-a:3',2'-d]imidazole (Glu-P-1).

1985 ◽  
Vol 62 ◽  
pp. 215-218
Author(s):  
Y Hashimoto ◽  
K Shudo
Keyword(s):  
Chemical Modification ◽  
Specific Binding ◽  
Base Sequence

Introduction of a specific binding domain on myoglobin surface by new chemical modification

2000 ◽  
Vol 82 (1-4) ◽  
pp. 133-139 ◽  
Author(s):  
Takashi Hayashi ◽  
Tsutomu Ando ◽  
Takaaki Matsuda ◽  
Hiroaki Yonemura ◽  
Sunao Yamada ◽  
...  
Keyword(s):  
Chemical Modification ◽  
Specific Binding ◽  
Binding Domain

THE CHEMICAL MODIFICATION OF CHYMOTRYPSIN

1964 ◽  
Vol 42 (6) ◽  
pp. 695-714 ◽  
Author(s):  
G. H. Dixon ◽  
H. Schachter
Keyword(s):  
Enzyme Activity ◽  
Amino Acid ◽  
Chemical Modification ◽  
Active Site ◽  
Specific Binding ◽  
Bond Breaking ◽  
Kinetic Properties ◽  
Side Chains ◽  
Amino Acid Side Chains

Chemical modification of chymotrypsin has led to the identification of several amino acid side-chains which are probably constituents of the active site of the enzyme. A single seryl and a single histidyl residue appear to cooperate in catalyzing the bond-breaking process while one or more tryptophanyl residues may be involved in the specific binding of substrate. Neither of the two methionyl residues is essential for enzyme activity although changes in kinetic properties occur when they are modified by oxidation or alkylation.

scholarly journals Bioimaging of Nucleolin Aptamer-Containing 5-(N-benzylcarboxyamide)-2′-deoxyuridine More Capable of Specific Binding to Targets in Cancer Cells

2010 ◽  
Vol 2010 ◽  
pp. 1-9 ◽  
Author(s):  
Kyue Yim Lee ◽  
Hyungu Kang ◽  
Sung Ho Ryu ◽  
Dong Soo Lee ◽  
Jung Hwan Lee ◽  
...  
Keyword(s):  
Chemical Modification ◽  
Cancer Cells ◽  
Specific Binding ◽  
Confocal Imaging ◽  
Critical Parameters ◽  
Significant Activity ◽  
Imaging Analysis ◽  
Modified Nucleotides ◽  
Chemically Modified ◽  
Fluorescence Measurements

Chemically modified nucleotides have been developed and applied into SELEX procedure to find a novel type of aptamers to fit with targets of interest. In this study, we directly performed chemical modification of 5-(N-benzylcarboxyamide)-2′-deoxyuridine (called 5-BzdU) in the AS1411 aptamer, which binds to the nucleolin protein expressed in cancer cells. Forty-seven compounds of AS1411-containing Cy3-labeled 5-BzdU (called Cy3-(5-BzdU)-modified-AS1411) were synthesized by randomly substituting thymidines one to twelve in AS1411 with Cy3-labeled 5-BzdU. Both statistically quantified fluorescence measurements and confocal imaging analysis demonstrated at least three potential compounds of interest: number 12, 29 and 41 that significantly increased the targeting affinity to cancer cells but no significant activity from normal healthy cells. These results suggest that the position and number of substituents in AS1411 are critical parameters to improve the aptamer function. In this study, we demonstrated that chemical modification of the existing aptamers enhanced the binding and targeting affinity to targets of interest without additional SELEX procedures.

DNA and desiccation tolerance

1994 ◽  
Vol 4 (2) ◽  
pp. 175-185 ◽  
Author(s):  
D. J. Osborne ◽  
I. I. Boubriak
Keyword(s):  
Conformational Changes ◽  
Desiccation Tolerance ◽  
Genetic Information ◽  
Specific Binding ◽  
Life Forms ◽  
Base Sequence ◽  
Lethal Effects ◽  
Dna Structures ◽  
Two Stages

AbstractThis article reviews mechanisms by which specialized cells of different life forms have overcome the lethal effects of dehydration and considers how the maintenance of genetic information is central to survival. As a dynamic and hydrated molecule in vivo, DNA can assume different conformational structures depending upon the water activity, the base sequence and the presence of specific binding proteins. The attainment of stable secondary structures that are resistant to degradation in vivo at low water potentials is proposed as a likely accompaniment to desiccation tolerance. In addition, chemical modification of bases in DNA, the extent of methylation and conformational changes could determine the expression of different gene sequences as cells pass from desiccation-tolerant to desiccation-intolerant states. We monitored the integrity of extracted DNA in embryos of seeds and in wind-dispersed pollen during transition from their desiccation tolerance to desiccation intolerance on hydration and germination. We present evidence to show that the DNA of these two stages is different and that it is the DNA from desiccation-tolerant cells only that retains integrity when the cells are subjected to desiccation regimes. We discuss these findings in relation to certain hydration-sensitive DNA structures and to other relevant biological systems.

Ultrastructural Localization of Antigens by Capillary Action Immunocytochemistry

1996 ◽  
Vol 54 ◽  
pp. 40-41
Author(s):  
László G. Kömüves
Keyword(s):  
San Francisco ◽  
Colloidal Gold ◽  
Specific Binding ◽  
Ultrastructural Localization ◽  
Ultrastructural Level ◽  
Uranyl Acetate ◽  
Adhesive Tape ◽  
Distilled Water ◽  
Capillary Action ◽  
Rabbit Igg

Light microscopic immunohistochemistry based on the principle of capillary action staining is a widely used method to localize antigens. Capillary action immunostaining, however, has not been tested or applied to detect antigens at the ultrastructural level. The aim of this work was to establish a capillary action staining method for localization of intracellular antigens, using colloidal gold probes.Post-embedding capillary action immunocytochemistry was used to detect maternal IgG in the small intestine of newborn suckling piglets. Pieces of the jejunum of newborn piglets suckled for 12 h were fixed and embedded into LR White resin. Sections on nickel grids were secured on a capillary action glass slide (100 μm wide capillary gap, Bio-Tek Solutions, Santa Barbara CA, distributed by CMS, Houston, TX) by double sided adhesive tape. Immunolabeling was performed by applying reagents over the grids using capillary action and removing reagents by blotting on filter paper. Reagents for capillary action staining were from Biomeda (Foster City, CA). The following steps were performed: 1) wet the surface of the sections with automation buffer twice, 5 min each; 2) block non-specific binding sites with tissue conditioner, 10 min; 3) apply first antibody (affinity-purified rabbit anti-porcine IgG, Sigma Chem. Co., St. Louis, MO), diluted in probe diluent, 1 hour; 4) wash with automation buffer three times, 5 min each; 5) apply gold probe (goat anti-rabbit IgG conjugated to 10 nm colloidal gold, Zymed Laboratories, South San Francisco, CA) diluted in probe diluent, 30 min; 6) wash with automation buffer three times, 5 min each; 7) post-fix with 5% glutaraldehyde in PBS for 10 min; 8) wash with PBS twice, 5 min each; 9) contrast with 1% OSO4 in PBS for 15 min; 10) wash with PBS followed by distilled water for5 min each; 11) stain with 2% uranyl acetate for 10 min; 12) stain with lead citrate for 2 min; 13) wash with distilled water three times, 1 min each. The glass slides were separated, and the grids were air-dried, then removed from the adhesive tape. The following controls were used to ensure the specificity of labeling: i) omission of the first antibody; ii) normal rabbit IgG in lieu of first antibody; iii) rabbit anti-porcine IgG absorbed with porcine IgG.

On the Role of Transferrin in 67Ga Uptake by Tumor Cells

1988 ◽  
Vol 27 (04) ◽  
pp. 151-153
Author(s):  
P. Thouvenot ◽  
F. Brunotte ◽  
J. Robert ◽  
L. J. Anghileri
Keyword(s):  
Specific Binding ◽  
Subcellular Fractionation ◽  
Animal Blood ◽  
Tumor Bearing ◽  
Cell Structures ◽  
The Difference ◽  
Sarcoma Cells ◽  
In Vitro Uptake

In vitro uptake of 67Ga-citrate and 59Fe-citrate by DS sarcoma cells in the presence of tumor-bearing animal blood plasma showed a dramatic inhibition of both 67Ga and 59Fe uptakes: about ii/io of 67Ga and 1/5o of the 59Fe are taken up by the cells. Subcellular fractionation appears to indicate no specific binding to cell structures, and the difference of binding seems to be related to the transferrin chelation and transmembrane transport differences

Plasminogen-Plasmin System IX. Specific Binding of Tranexamic Acid to Plasmin

1975 ◽  
Vol 33 (03) ◽  
pp. 573-585 ◽  
Author(s):  
Masahiro Iwamoto
Keyword(s):  
Tranexamic Acid ◽  
Affinity Chromatography ◽  
Dissociation Constant ◽  
Factor Xiii ◽  
Specific Binding ◽  
The Other ◽  
Inhibitory Mechanism ◽  
Binding Studies ◽  
Similar Affinity ◽  
Fibrin Structure

SummaryInteractions between tranexamic acid and protein were studied in respect of the antifibrinolytic actions of tranexamic acid. Tranexamic acid did neither show any interaction with fibrinogen or fibrin, nor was incorporated into cross-linked fibrin structure by the action of factor XIII. On the other hand, tranexamic acid bound to human plasmin with a dissociation constant of 3.5 × 10−5 M, which was very close to the inhibition constant (3.6 × 10−5 M) for this compound in inhibiting plasmin-induced fibrinolysis. The binding site of tranexamic acid on plasmin was not the catalytic site of plasmin, because TLCK-blocked plasmin also showed a similar affinity to tranexamic acid (the dissociation constant, 2.9–4.8 × 10−5 M).In the binding studies with the highly purified plasminogen and TLCK-plasmin preparations which were obtained by affinity chromatography on lysine-substituted Sepharose, the molar binding ratio was shown to be 1.5–1.6 moles tranexamic acid per one mole protein.On the basis of these and other findings, a model for the inhibitory mechanism of tranexamic acid is presented.

Concanavalin A-induced Aggregation of Human Blood Platelets

1975 ◽  
Vol 33 (02) ◽  
pp. 354-360 ◽  
Author(s):  
Heinrich Patscheke ◽  
Reinhard Brossmer
Keyword(s):  
Concanavalin A ◽  
Binding Capacity ◽  
Specific Binding ◽  
Blood Platelets ◽  
Residual Effect ◽  
Independent Effect ◽  
Con A ◽  
Experimental Conditions ◽  
Main Effect ◽  
Induced Aggregation

SummaryConcanavalin A (CON A) causes platelets to aggregate. A Ca++-independent effect of CON A could be separated from a main effect which depends on Ca++. The main effect probably is a consequence of the CON A-induced platelet release reaction and therefore is platelet-specific. The weak residual effect observed in the presence of Na2EDTA may be due to a similar mechanism as has been demonstrated for CON A-induced aggregations of several other normal and malignant transformed animal cells.Na2EDTA did not inhibit the carbohydrate-specific binding capacity of CON A. Therefore, Na2EDTA appears not to demineralize the CON A molecules under these experimental conditions.α-methyl-D-glucoside inhibits the Ca++-independent as well as the Ca++-dependent effect of CON A.Pretreatment by neuraminidase stimulated the platelet aggregation induced by CON A. It is possible that removal of terminal sialic acid residues makes additional receptors accessible for the binding of CON A.

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