Hydrogen-transfer alternating copolymerization of vinylphosphonic acid monoethyl ester with cyclic phosphonites. A new oxidation-reduction copolymerization

1989 ◽  
Vol 22 (11) ◽  
pp. 4390-4392 ◽  
Author(s):  
Shiro Kobayashi ◽  
Junichi Kadokawa ◽  
I Fang Yen ◽  
Shinichiro Shoda
Keyword(s):  
Hydrogen Transfer ◽  
Oxidation Reduction ◽  
Vinylphosphonic Acid ◽  
Alternating Copolymerization

scholarly journals Alternating copolymerization of cyclic germylenes with N-phenyl-p-quinoneimine via oxidation-reduction process

2016 ◽  
Vol 48 (9) ◽  
pp. 969-972
Author(s):  
Hiroshi Takano ◽  
Masafumi Hiraishi ◽  
Shigeru Yaguchi ◽  
Satoru Iwata ◽  
Shin-ichiro Shoda ◽  
...  
Keyword(s):  
Reduction Process ◽  
Oxidation Reduction ◽  
Alternating Copolymerization

scholarly journals Oxidation-reduction alternating copolymerization of germylene and N-phenyl-p-quinoneimine

2014 ◽  
Vol 47 (1) ◽  
pp. 31-36 ◽  
Author(s):  
Satoru Iwata ◽  
Mitsunori Abe ◽  
Shin-ichiro Shoda ◽  
Shiro Kobayashi
Keyword(s):  
Oxidation Reduction ◽  
Alternating Copolymerization

scholarly journals The Structure and Function of Oestrogens. VII The Use of (9,12,12-2H3)- and (11x,12,12-2H3) Oestradiol in a Test of the Quinone Methide Hypothesis for Oestrogen Action

1983 ◽  
Vol 36 (3) ◽  
pp. 315
Author(s):  
David J Collins ◽  
Grant M Stone ◽  
Magnus Axelson
Keyword(s):  
Hydrogen Transfer ◽  
Quinone Methide ◽  
Control Group ◽  
Gas Liquid Chromatography ◽  
Ovariectomized Mice ◽  
Oxidation Reduction ◽  
Reduction Cycle ◽  
Physiological Dose ◽  
And Function ◽  
Stimulation Of

Ovariectomized mice were injected hi.travaginally with a physiological dose of (9,12, 12-2H3)oestradiol (3), and a control group was similarly injected with (llc;,12,12-2H3)oestradiol (4). Gas-liquid chromatography/mass spectrometry (g.l.c./m.s.) analysis of the oestradiols recovered from the vaginae of the two sets of mice showed that the content and distribution of deuterium were the same as in the respective pure trideuterated oestradiols (3) and (4). This proved conclusively that the 9oc-hydrogen of oestradiol is not exchanged during residence in and stimulation of the vagina. It therefore appears unlikely that reversible quinone methide formation in oestradiol is the trigger mechanism for stimulation of RNA synthesis, unless a hydrogen transfer relay system permits repetitive removal and replacement of the hydrogen atom at C9 during the oxidation-reduction cycle.

Isomerization

2007 ◽  
Author(s):  
Perry A. Frey ◽  
Adrian D. Hegeman
Keyword(s):  
Driving Force ◽  
Hydrogen Transfer ◽  
Triosephosphate Isomerase ◽  
Hydride Transfer ◽  
Aldehyde Group ◽  
Isomerization Reaction ◽  
Chemical Mechanisms ◽  
Phosphohexose Isomerase ◽  
Oxidation Reduction ◽  
Similar Chemical

Isomerization reactions are important in metabolism to potentiate further transformations that would otherwise be chemically impossible. A familiar example from glycolysis is phosphohexose isomerase, which catalyzes the interconversion of D-glusose-6-P and D-fructose-6-P. The formation of fructose-6-P makes it chemically feasible at a later step of glycolysis to cleave the six-carbon sugar into two three-carbon sugars, glyceraldehyde-3-P, and dihydroxyacetone-P by aldolase. No such cleavage of glucose-6-P into two three-carbon sugars is possible. The dihydroxyacetone-3-P is converted into glyceraldehyde-3-P by another isomerase, triosephosphate isomerase. In this way, glucose-6-P can be transformed into two molecules of glyceraldehyde-3-P, which can then be metabolized through glycolysis to pyruvate. Both reactions of phosphohexose and triosephosphate isomerases involve aldose/ketose interconversions and proceed by similar chemical mechanisms. Other important isomerases include phosphomutases, epimerases, racemases, and carbon-skeleton mutases, all of which have their roles in metabolism. The chemical mechanisms vary with the classes of isomerases and include enolizations, hydride transfer, oxidation/reduction, phosphotransfer, and radical rearrangements. In this chapter, we consider the mechanisms by which enzymes catalyze isomerization reaction. The interconversions of glucose-6-P and fructose-6-P and of the triose phosphates can be formulated chemically. The transformation in is an internal oxidation-reduction, in which the aldehyde group of the aldose is reduced and the neighboring alcoholic group is oxidized. This reaction can take place by either of two chemical mechanisms: an initial enolization at C2 to produce an enediolate intermediate that can be protonated at C1 to produce the product or a direct hydride transfer from C2 to C1. These mechanisms are outlined in scheme 7-1. Loss of the proton C2(H) by enolization in the upper pathway leads to the enediolate intermediate, and return of the proton to C1 (black arrows in scheme 7-1) leads to the ketose product. The hydride transfer mechanism in the lower pathway begins with the dissociation of the alcoholic proton to form the alcoholate intermediate. The alcoholate provides the driving force for the 1,2-hydride transfer (colored arrows in scheme 7-1) accompanied by protonation of the oxygen at C1. The two mechanisms require different hydrogen transfer regimes.

Pentose phosphate shunt, pyridine nucleotides, glutathione, and insulin secretion of fetal islets

1983 ◽  
Vol 244 (4) ◽  
pp. E354-E360
Author(s):  
H. P. Ammon ◽  
G. Bumiller ◽  
H. Duppenbecker ◽  
E. Heinze ◽  
S. Lutz ◽  
...  
Keyword(s):  
Insulin Secretion ◽  
Insulin Release ◽  
Hydrogen Transfer ◽  
Pentose Phosphate ◽  
Pyridine Nucleotides ◽  
Adult Rats ◽  
Oxidation Reduction ◽  
Fetal Rats ◽  
Fetal Islets ◽  
Pentose Phosphate Shunt

In rat fetal islets it was tested whether their failure to respond to glucose with insulin secretion might be due to inadequate changes of the redox state of pyridine nucleotides and of glutathione. In islets of newborn (5 days) and adult (3 mo) rats elevation of glucose produced an increase in insulin secretion, pentose phosphate shunt (PPS) activity, and NADPH/NADP, NADH/NAD, and GSH/GSSG ratios. An increase in the NADH/NAD ratio was also observed in islets of fetal rats, but in contrast to islets of newborns and adults no increase in insulin release, PPS activity, and the GSH/GSSG ratio was observed. However, at all glucose concentrations tested islets of fetal rats exhibited a high NADPH/NADP ratio similar to the ratio of adult rats in the presence of 16.7 mM glucose. It is suggested that in fetal islets there exists a lack of hydrogen transfer from NADPH to GSSG. The high NADPH/NADP ratio may in turn suppress PPS activity. It is possible that the missing insulin release of fetal islets in response to glucose is at least in part due to the fact that the oxidation-reduction state of the GSH/GSSG system also does not respond to the elevation of the glucose concentration.

Hydrogen-transfer polymerization of vinylphosphonic acid monoethyl ester

1992 ◽  
Vol 25 (24) ◽  
pp. 6690-6692 ◽  
Author(s):  
Shiro Kobayashi ◽  
Junichi Kadokawa ◽  
I. Fang Yen ◽  
Hiroshi Uyama ◽  
Shinichiro Shoda
Keyword(s):  
Hydrogen Transfer ◽  
Vinylphosphonic Acid ◽  
Hydrogen Transfer Polymerization

Effect of Niacin on Mitochondria of Allium Cepa Root Cells

1967 ◽  
Vol 25 ◽  
pp. 78-79
Author(s):  
M. Arif Hayat
Keyword(s):  
Nicotinamide Adenine Dinucleotide ◽  
Hydrogen Transfer ◽  
Nicotinamide Adenine Dinucleotide Phosphate ◽  
Nicotinamide Adenine ◽  
Root Tips ◽  
Root Cells ◽  
Transfer Processes ◽  
Standard Procedures ◽  
A Cell ◽  
Critical Interest

Although it is recognized that niacin (pyridine-3-carboxylic acid), incorporated as the amide in nicotinamide adenine dinucleotide (NAD) or in nicotinamide adenine dinucleotide phosphate (NADP), is a cofactor in hydrogen transfer in numerous enzyme reactions in all organisms studied, virtually no information is available on the effect of this vitamin on a cell at the submicroscopic level. Since mitochondria act as sites for many hydrogen transfer processes, the possible response of mitochondria to niacin treatment is, therefore, of critical interest.Onion bulbs were placed on vials filled with double distilled water in the dark at 25°C. After two days the bulbs and newly developed root system were transferred to vials containing 0.1% niacin. Root tips were collected at ¼, ½, 1, 2, 4, and 8 hr. intervals after treatment. The tissues were fixed in glutaraldehyde-OsO4 as well as in 2% KMnO4 according to standard procedures. In both cases, the tissues were dehydrated in an acetone series and embedded in Reynolds' lead citrate for 3-10 minutes.

Sign in / Sign up

Export Citation Format

Share Document