Đây là bài giảng của thầy Đỗ Hiếu Liêm, trường ĐH Nông Lâm TP.HCM. Chuỗi hô hấp mô bào bao gồm các phản ứng oxid hoá
khử liên tục trên các cơ chất (sản phẫm biến dưỡngtrung gian - Chu trình Krebs và β oxid hoá acid béo). Tổ chức: hệthống enzyme CHH với các coenzyme tổchức thành từng tổ hợp và sắp xếp theo thứ tự tăng dầnđiện thế oxid hoá khử,bắđầu NAD+ dehydrogenase có điện thế âm và cuối cùng là cytochrome oxidase có điện thế dương....
Catalytic oxidation of organic compounds is an extremely important field of chemistry, spanning the range from biological oxidations to large scale industrial production of commodity chemicals. However, many of these transformations can hardly be classified as organometallic reactions, since the catalysts (often simple metal salts) and the intermediates can be rather regarded as coordination complexes than organometallic compounds.
In order to meet the increasing demand for valve-regulated lead–acid ŽVRLA. batteries, a new soft lead has been produced by Pasminco Metals. In this material, bismuth is increased to a level that produces a significant improvement in battery cycle life. By contrast, other common impurities, such as arsenic, cobalt, chromium, nickel, antimony and tellurium, that are known to be harmful to VRLA batteries are controlled to very low levels. A bismuth ŽBi.-bearing oxide has been manufactured ŽBarton-pot method. ...
For many years, the plates of leadracid batteries have been produced from leady oxide, a mixture of finely divided lead Ž‘free-lead’. and lead monoxide. Although this material is generally satisfactory, it suffers from the disadvantages that it is variable in composition and requires complicated and lengthy processing after pasting to remove the residual free-lead. Plates made from leady oxide also require cycling before they achieve their full performance, and this can result in either depressed initial capacity or additional processing cost. ...
Mục đích của chúng tôi là khảo sát ảnh hưởng nồng độ tiền chất vào kích thước và tính
chất từ của các hạt nano oxide sắt từ Fe3O4 bằng phương pháp đồng kết tủa. Chúng tôi
nhận thấy rằng kích thước tinh thể và từ tính của các hạt gần như không phụ thuộc vào
sự thay đổi hệ số đương lượng, và nồng độ các muối sắt ban đầu.
Early metabolic steps, including glycolysis and the activity of the pyruvate dehydrogenase complex, yield a two-carbon fragment called an acetyl group, which is linked to a large cofactor known as coenzyme A (or CoA). It is during the citric acid cycle that acetyl-CoA is oxidized to the waste product, carbon dioxide, along with the reduction of the cofactors NAD+ and ubiquinone
Almost 4000 years ago Egyptians and Babylonians
used aluminum compounds in various
chemicals and medicines. Herodotus mentioned
alum in the fifth century b.c. and Pliny
referred to “alumen,” now known as alum, as a
mordant to fix dyes to textiles around 80 a.d.
In 1754 Marggraf showed that a distinct compound
existed in both alum and clays. In 1761
the French chemist Guyton de Morveau proposed
the name “alumine” for the base in alum,
identified in 1787 by Antoine Lavosier as the oxide of a then-undiscovered element.
The increased level of reactive oxygen species (ROS) in living organisms over 60 years
ago was implicated in the development of diseases and aging (Harman, 1956; 1983).
This book is a collective scientific monograph presenting several important aspects
related to ROS role in human and animal pathologies. In 1985, German scientist
Helmut Sies first denoted oxidative stress concept, which immediately attracted
attention of researchers in diverse basic fields. Several discoveries substantially
stimulated the interest to ROS as ones related to many diseases.
Clostridial glutamate dehydrogenase mutants, designed to accommodate
the 2¢-phosphate of disfavoured NADPH, showed the expected large speci-ficity shifts with NAD(P)H. Puzzlingly, similar assays with oxidized cofac-tors initially revealed little improvement with NADP
, although rates with
were markedly diminished.
Polyamine oxidases are FAD-dependent enzymes catalyzing the oxidation
of polyamines at the secondary amino groups.Zea maysPAO (ZmPAO)
oxidizes the carbon on the endo-side of the N5-nitrogen of spermidine
(Spd) and spermine (Spm).
The nitrite reductase activity of deoxyhemoglobin has received much recent
interest because the nitric oxide produced in this reaction may participate
in blood flow regulation during hypoxia. The present study used spectral
deconvolution to characterize the reaction of nitrite with carp and rabbit
hemoglobin at different constant oxygen tensions that generate the full
range of physiological relevant oxygen saturations.
The membrane lipid composition of planctomycetes capable of the an-aerobic oxidation of ammonium (anammox), i.e. Candidatus‘Brocadia
anammoxidans’ and Candidatus‘Kuenenia stuttgartiensis’, was shown to
be composed mainly of so-called ladderane lipids. These lipids are com-prised of three to five linearly concatenated cyclobutane moieties withcis
ring junctions, which occurred as fatty acids, fatty alcohols, alkyl glycerol
monoethers, dialkyl glycerol diethers and mixed glycerol ether⁄esters. ...
Bài giảng "Cân bằng oxid hóa – khử điện hóa học" trình bày các nội dung: Phản ứng oxid hóa – khử và cặp oxid hóa khử liên hợp, điện cực, thế điện cực, một số nguồn điện hóa thông dụng. Mời các bạn cùng tham khảo nội dung chi tiết.
Fatty acids (FAs) can be degraded via different mechanisms including
a-, b- and x-oxidation. In humans, a range of different genetic diseases has
been identified in which either mitochondrial FAb-oxidation, peroxisomal
FAb-oxidation or FAa-oxidation is impaired. Treatment options for most
of these disorders are limited.
Mitochondria are dynamic organelles that undergo continual fusion and
fission to maintain their morphology and functions, but the mechanism
involved is still not clear. Here, we investigated the effect of mitochondrial
oxidative stress triggered by high-fluence low-power laser irradiation (HF-LPLI) on mitochondrial dynamics in human lung adenocarcinoma cells
(ASTC-a-1) and African green monkey SV40-transformed kidney fibroblast
There is growing evidence that altered production and⁄or spatio-temporal
distribution of reactive oxidant species and reactive nitrosative species
in blood creates oxidative and⁄or nitrosative stresses in the failing myo-cardium and endothelium.
Methemoglobin (metHb), an oxidized form of hemoglobin, is unable to
bind and carry oxygen. Erythrocytes are continuously subjected to oxida-tive stress and nitrite exposure, which results in the spontaneous formation
of metHb. To avoid the accumulation of metHb, reductive pathways medi-ated by cytochrome b5 or flavin,
Thioredoxin reductase (TrxR) fromEscherichia coli,the
mutant proteins E159Y and C138S, and the mutant
protein C138Streated with phenylmercuric acetate were
reconstituted with [U-13
N4]FAD and analysed, in
their oxidized and reduced states, by
P-NMR spectroscopy. The enzymes studied showed
P-NMR spectra in the oxidized state, con-sisting of two peaks at )9.8 and )11.5 p.p.m. In the
reduced state, the two peaks merge into one apparent
peak (at)9.8 p.p.m.)....
Homocysteine (Hcy) is anonprotein-forming sulphur amino
acid that plays an important role in remethylation and
trans-sulphuration processes. In recent years, it has been
suggested that increased levels of plasma Hcy may play a
role in the pathogenesis of various diseases, particularly
at the cardiovascular level. The pathogenic mechanism of
hyperhomocysteinemia, however, has not been clarified.
In rat neuronal nitric oxide synthase, Phe1395 is positioned
over the FAD isoalloxazine ring. This is replaced by Trp676
in human cytochrome P450 reductase, a tryptophan in
related diflavin reductases (e.g. methionine synthase reduc-tase andnovel reductase 1), and tyrosine inplant ferredoxin-NADP
reductase. Trp676 in human cytochrome P450
reductase is conformationallymobile, andplays akey role in
enzyme reduction. Mutagenesis of Trp676 to alanine results
in a functional NADH-dependent reductase. ...