No abstract

Products of lipid peroxidation (malonaldehyde, Schiff-bases) were detected in human skin. These products were increased after UV-light exposition, on chronically sun-exposed areas as well as with advancing age. Malonaldehyde cross linked epidermal glucose-6-phosphate-dehydrogenase and diminished their activity.

Yeast PFK had a sedimentation coefficient of 16.7 S both in the absence and in the presence of ATP, and did not dissociate even at very low protein concentrations. Sodium dodecyl-sulphate caused dissociation of the protein to subunits of 3.2 S.The effects of pH on substrate affinities are described. In the presence of UTP, acting as non-inhibiting phosphate donor, the behaviour of the enzyme towards F-6-P was co-operative, with a Hill coefficient of 2.2.

Yeast phosphofructokinase binds to Blue Dextran 2000@ with remarkable high affinity. Whereas phosphofructokinase from muscle and erythrocytes also have high affinity t o Blue Dextran, aldolase, hexokinase, pyruvate kinase from muscle and glyceraldehyde-3-phosphate dehydrogenase show no affinity to this chromophore.The chromophoric component of Blue Dextran seems to be responsible for these interactions, because chromophore-free dextran 2000 does not show any affinity to phosphofructokinases.Blue Dextran immobilized by fixation in cross-linked polyacrylamide gel can be used as a valuable tool for affinity chromatography of phosphofructokinase. The conditions of binding, namely pH dependence, effects of ionic strength and of enzyme effectors have been studied using gel-fixed phosphofructokinase. ATP (2-3 mM) but not ITP (up to 5 mM) specifically splits the enzyme chromophore complex.With