| 1. |
- Mattiasson, Bo, et al.
(författare)
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Studies on a matrix-bound three-enzyme system.
- 1971
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Ingår i: Biochimica et Biophysica Acta - General Subjects. - : Elsevier BV. - 0304-4165 .- 0005-2744. ; 235:1, s. 253-257
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Tidskriftsartikel (refereegranskat)
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| 2. |
- Dahlqvist-Edberg, Ulla, et al.
(författare)
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Purification of a Ca2+-activated protease from rat erythrocytes and its possible effect on pyruvate kinase in vivo
- 1981
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Ingår i: Biochimica et Biophysica Acta-Enzymology. - : Elsevier BV. - 0005-2744. ; 660:1, s. 96-101
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Tidskriftsartikel (refereegranskat)abstract
- A Ca2+-activated protease with [32P]phosphopyruvate kinase as substrate was purified to about 50% from rat erythrocytes. The purification involved chromatography on Sepharose/Sephadex gels, DEAE-cellulose and (NH4)2SO4 precipitation. The protease required 3.3 mM Ca2+ for full activity. When pyruvate kinase (ATP: pyruvate 2-O-phosphotransferase, EC 2.7.1.40) was purified from erythrocytes incubated with [32P]phosphate it contained 0.5 mol [32P]phosphate/mol enzyme subunit. When 3.3 mM Ca2+ were added at hemolysis this incorporation decreased. The possible importance of this Ca2+-activated protease for the regulation of pyruvate kinase in erythrocytes is discussed.
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| 3. |
- Eriksson, Caj, et al.
(författare)
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Lipoxygenase from peas, purification and properties of the enzyme
- 1970
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Ingår i: BBA - Enzymology. - : Elsevier BV. - 0005-2744. ; 198:3, s. 449-459
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Tidskriftsartikel (refereegranskat)abstract
- 1. 1. Lipoxygenase (linoleate:oxygen oxidoreductase, EC 1.13.1.13.) from peas was extensively purified by precipitation with (NH4)2SO4, gel filtration with Sephadex G-150, and ion-exchange chromatography on DEAE-cellulose. 2. 2. The final enzyme preparation proved homogeneous by ultracentrifugation of a 0.6% protein solution (pH 7.0) but separated into two main and narrow fractions on isoelectric focusing, pI values 5.80-5.82. 3. 3. The molecular weight, as calculated on the basis of amino acid analysis and ultracentrifugation, was found to be 72 000 and 67 000, respectively. 4. 4. Pea lipoxygenase contains 7 half-cystine residues, different from the soybean enzyme which has been reported to contain none. © 1970.
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| 4. |
- Ek, Pia, et al.
(författare)
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The kinetics of unphosphorylated, phosphorylated and proteolytically modified fructose bisphosphatase from rat liver
- 1981
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Ingår i: Biochimica et Biophysica Acta. - 0005-2744. ; 662:2, s. 265-270
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Tidskriftsartikel (refereegranskat)abstract
- Phosphorylation of fructose-bisphosphatase (D-fructose-1,6-bisphosphate 1-phosphohydrolase, EC 3.1.3.11) by the catalytic subunit of cyclic AMP-dependent protein kinase from pig muscle decreased the K0.5 for fructose-bisphosphate from 21 to 11 microM. When the phosphorylated fructose-bisphosphatase was treated with trypsin the K0.5 increased to 22 microM. The K0.5 also increased when the phosphoenzyme was treated with a partially purified phosphatase from rat liver. There was no difference between the unphosphorylated and phosphorylated enzyme with respect to pH dependence, the pH optimum being about 7.0 for both. Limited treatment of fructose-bis-phosphatase with subtilisin, which cleaves the enzyme at its unphosphorylatable N-terminal part, increased the pH optimum more than limited treatment with trypsin, which releases the phosphorylated peptide at the C-terminal part of fructose-bisphosphatase. The phosphorylated site on the phosphorylated fructose-bisphosphatase was more easily split off by trypsin treatment than the corresponding unphosphorylated site. The results suggest in addition to the glucagon-induced phosphorylation of fructose-bisphosphatase described by Claus et al. [1] that the phosphorylation-dephosphorylation of fructose-bisphosphatase could be of importance for the hormonal regulation of the enzyme in vivo.
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