The quantification of eight enzymes from the ageing rat lens, with respect to sex differences and special reference to aldolase

Abstract

Eight enzymes, e.g. lactate dehydrogenase, malate dehydrogenase, fructose-diphosphate aldolase, sorbitol dehydrogenase, glucose-6-phosphate dehydrogenase, hexokinase, phosphofructokinase and pyruvate kinase were estimated quantitatively in the rat lens from 37 to 1,211 days of age, by spectrophotometric methods. The activity was expressed as mU/g LWW. All enzymes measured showed declining activities, but LDH, ALD, SDH, G-6-PDH, HK and PFK gave a significant decrease during ageing when plotted semi-logarithmically from 37 to 1,211 days. SDH and G-6-PDH showed a statistically significant difference between the enzymes from the male and the female lenses. The female lens always had a lower activity than the male lens. Of all enzymes the specific activity, expressed as mU/l mg protein, was calculated. This specific activity appeared to be rather constant during ageing, except for ALD. In the female lenses, the specific activity of 7 enzymes was lower than in the male lenses. For ALD the specific activity decreased significantly in the male lens from 5.32 at 37 days to 0.88 at 1,211 days. In the female lens this significant decrease was from 4.97 to 0.81.

Activation of phosphotyrosine phosphatase activity is associated with decreased differentiation in adult bovine lens

“…We report herein that an activity of one or more PTPases is found to be increased in the equatorial bovine lens epithelium with advancing age. Our results differ from those obtained thus far, since investigations generally show that the specific activities of enzymes decrease with age in the lens (Hockwin and Ohrloff, 1981;Bours et al, 1988). We also show that this dephosphorylating activity acts on two major membrane substrates when stimulated by bFGF: an unidentified 18 kD, protein and a substrate of 34 kD, identified as a lipocortin 2-related immunologically protein.…”

Oxidative stress in the aging murine olfactory bulb: Redox proteomics and cellular localization

“…This protein has been reported to be a specific target of oxidation under conditions of oxidative stress in other tissues as well (Koeck et al, 2004; Reverter‐Branchat et al, 2004; Barreiro et al, 2005) ALDO1 associates with the mitochondrial outer membrane (Taylor et al, 2003), bringing it into close contact with superoxide radicals and peroxynitrite (Koeck et al, 2004) that would facilitate its oxidation. Increased carbonylation of ALDO1 has been demonstrated to result in decreased enzyme activity (Barreiro et al, 2005); decreases in activity with aging have been observed in rat lens (Bours et al, 1988) and mouse liver (Gershon and Gershon, 1973). ALDO1 was localized primarily in a subset of astrocytes in the granule cell layer of the OB.…”

Chemical Modification of Lysozyme, Glucose 6-Phosphate Dehydrogenase, and Bovine Eye Lens Proteins Induced by Peroxyl Radicals: Role of Oxidizable Amino Acid Residues

“…A decrease in G6PD concentration has been reported in cataracts 13−15 and aged ocular lenses. 16 Bovine lens proteins (BLP) are primarily crystalline species that possess a highly ordered multimeric arrangement and are densely packed. This conformation provides and is critical to the transparency required for normal lens function.…”

“…G6PD is a dimeric globular enzyme present in the epithelial cells that cover the ocular lens and plays an important role in protection against oxidative stress due to its capacity to supply the NADPH required by the enzymes glutathione reductase, which is present at high concentrations in the eye’s lens, and thioredoxin reductase, as well as multiple other cellular processes. A decrease in G6PD concentration has been reported in cataracts − and aged ocular lenses . Bovine lens proteins (BLP) are primarily crystalline species that possess a highly ordered multimeric arrangement and are densely packed.…”