Characteristics of NAD-dependent?-glycerophosphate dehydrogenase from musc les of some vertebrates and man determined by llectrophoresis and isoelectric focusing in polyacrylamide gel

1980 ◽  
Vol 90 (2) ◽  
pp. 1066-1069
Author(s):  
S. A. Tumakov ◽  
I. V. Sidorenkov ◽  
S. V. Pervushkin
1979 ◽  
Vol 44 (6) ◽  
pp. 1828-1834
Author(s):  
Asja Šiševa ◽  
Jiřina Slaninová ◽  
Tomislav Barth ◽  
Stephan P. Ditzov ◽  
Luben M. Sirakov

Isoelectric focusing on polyacrylamide gel columns of three native crystalline commercial preparations of insulin and 125I-labelled insulin was carried out. All the compounds studied contained three components of different isoelectric points. The largest fraction, having pI 5.60 ± 0.05, was common to all preparations. The other two fractions were situated in the acid region of pH between pI 4.5 and 5.2. The presence of these fractions is explained by the contamination of crystalline insulins by proinsulin and by the formation of des-amido derivatives during the dissolving and storage of insulin samples, and, in case of labelled insulin, also by the presence of heavily iodinated insulin and contaminating components. The isoelectric focusing of the complex 125I-insulin-antibody showed a peak of radioactivity having pI 6.15 ± 0.05.


1980 ◽  
Vol 188 (2) ◽  
pp. 535-540 ◽  
Author(s):  
A Tomoda ◽  
M Ida ◽  
A Tsuji ◽  
Y Yoneyama

The time course of methaemoglobin reduction in human erythrocytes treated with nitrite was studied at pH 7.4, 37 degrees C, in the presence or absence of Methylene Blue, and the changes in methaemoglobin, intermediate haemoglobins and oxyhaemoglobin during the reaction were analysed by isoelectric-focusing on Ampholine/polyacrylamide-gel plates. In both cases, with or without the dye, the intermediate haemoglobins were found to be present at (alpha 3+beta 2+)2 and (alpha 2+beta 3+)2 valency hybrids from their characteristic position on electrophoresis, but amounts changed consecutively with time. The amount of (alpha 3+beta 2+)2 was always greater than that of the (alpha 2+beta 3+)2 valency hybrid. This result is explained by the differences in redox potentials between alpha- and beta-chains in methaemoglobin tetramer. It was concluded that methaemoglobin was reduced in human erythrocytes through these two different pats: methaemoglobin leads to k+3 (alpha 2+beta 3+)2 leads to k+3 oxyhaemoglobin. The reaction rate constants k'+1 (= k+1+k+3) and k'+2(=k+2+k+4) were estimated from the changes in each component methaemoglobin, intermediate haemoglobins [(alpha 3+beta 2+)2+(alpha 2+beta 3+)2] and oxyhaemoglobin.


1983 ◽  
Vol 1983 (11) ◽  
pp. 39-42
Author(s):  
Masaharu KOTANI ◽  
Kenji TSUNODA ◽  
Tatsuro SHIMAOKA

FEBS Letters ◽  
1972 ◽  
Vol 24 (1) ◽  
pp. 89-92 ◽  
Author(s):  
J. Söderholm ◽  
P. Allestam ◽  
T. Wadström

1980 ◽  
Vol 192 (1) ◽  
pp. 9-18 ◽  
Author(s):  
I R Cottingham ◽  
C I Ragan

L-3-Glycerophosphate dehydrogenase (EC 1.1.99.5) was purified from pig brain mitochondria by extraction with deoxycholate, ion-exchange chromatography and (NH4)2SO4 fractionation in cholate, and preparative isoelectric focusing in Triton X-100. Sodium dodecyl sulphate/polyacrylamide gel electrophoresis shows that the purified enzyme consists of a single subunit of mol.wt. 75 000. The enzyme contains non-covalently bound FAD and low concentrations of iron and acid labile sulphide. No substrate reducible e.p.r. signals were detected. The conditions of purification, particularly the isoelectric focusing step, lead to considerable loss of FAD and possibly iron-sulphur centres. It is therefore not possible to decide with certainty whether the enzyme is a flavoprotein or a ferroflavoprotein. The enzyme catalyses the oxidation of L-3-glycerophosphate by a variety of electron acceptors, including ubiquinone analogues. A number if compounds known to inhibit ubiquinone oxidoreduction by other enzymes of the respiratory chain failed to inhibit L-3-glycerophosphate dehydrogenase, except at very high concentrations.


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