Reddy, G Bhanuprakash and Bhat, K Seetharam (1998) UVB irradiation alters the activities and kinetic properties of the enzymes of energy metabolism in rat lens during aging. In: Journal of Photochemistry and Photobiology B: Biology, 42 (01). pp. 40-46.
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Ultraviolet (UV) radiation is one of the major risk factors of cataract (loss of eye-lens transparency). The influence of UVB radiation (300 nm, 100 mu W cm(-2)) on the activity and apparent kinetic constants (K-m and V-max) of rat lens hexokinase (HK;EC220.127.116.11), phosphofructokinase (PFK;EC18.104.22.168), isocitrate dehydrogenase (ICDH;EC22.214.171.124) and malate dehydrogenase (MDH;EC126.96.36.199) of energy metabolism has been investigated by irradiating the lens homogenate of three-and 12-month-old rats. In the three-month-old group specific activities of HK and PFK are reduced by 56 and 43 %, respectively, and there is no change in ICDH and MDH activities after a 24 h exposure. On the other hand, in the 12-month-old group the decreases are 72, 71, 24 and 16 % for HK, PFK. ICDH and MDH, respectively. UVB irradiation increases the apparent K-m of HK and PFK (in both age groups), whereas the K-m of ICDH and MDH is not altered. While the decrease in V-max of these enzymes due to UVB exposure is only marginal in three-month-old rats, it is more pronounced (significant) in 12-month-old rats. A similar decrease in enzyme activities of HK and PFK is also observe upon UVB exposure of the intact rat lens. The photoinduced changes in energy metabolism may in turn have a bearing on lens transparency, particularly at an older age.
|Item Type:||Journal Article|
|Additional Information:||Copyright of this article belongs to Elsevier Science.|
|Keywords:||Aging;Lens enzymes;Rats;Ultraviolet radiation.|
|Department/Centre:||Division of Biological Sciences > Molecular Biophysics Unit|
|Date Deposited:||04 Jan 2010 09:53|
|Last Modified:||19 Sep 2010 05:29|
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