Investigations of enzyme activities in fractions of water-soluble proteins of different old bovine lenses and single parts of the lenses after separation by gel filtration: Paper from the symposium ȁlens proteins and related subjectsȁ, Ghent, Belgium, June 1967

Abstract

The enzyme activities and the composition of the water-soluble proteins show distinct changes with increasing age. In order to determine whether or not there is a relationship between the changes in proteins and enzymes, the water-soluble proteins of bovine lenses of various ages and of different parts of the lenses (equatorial, anterior layer, posterior layer and nucleus) were separated using gel filtration with Sephadex G-200. In all experiments five fractions were obtained. The percentages of the single fractions were almost identical in the equatorial, anterior and posterior cortical layers of calf and bovine lenses, whereas the percentage distribution of the lens-nucleus differs from them. After separation, enzymatic analyses were performed by measuring the activities of fructose diphosphate aldolase, lactate dehydrogenase, malate dehydrogenase, glucose-6-phosphate dehydrogenase, NAD-sorbitol dehydrogenase, hexokinase, glycerokinase and pyruvate kinase. Enzyme activities are found qualitatively in 4ȁ5 protein fractions, with the exception of glucose-6-phosphate dehydrogenase. The main activities were in fractions II and/or III. The results show influence of the age of the single lens fibers and of the age of the animal when the fibers were formed. The question of the presence of isoenzymes in the lens is discussed.