Isoelectric focusing studies of aldehyde dehydrogenases, alcohol dehydrogenases and oxidases from mammalian anterior eye tissues

Abstract

1. 1. Isoelectric focusing (IEF) and zymogram methods were used to examine the tissue distribution, multiplicity and substrate specificities of alcohol dehydrogenases (ADHs), aldehyde dehydrogenases (ALDHs) and ocular oxidases (EOXs) from mammalian anterior eye tissues. 2. 2. Baboon, cattle, pig and sheep corneal extracts exhibited high ALDH activities; the corneal ALDHs were distinct from the major liver ALDHs and distinguished by their preference for medium-chain aldehydes. 3. 3. Baboon and pig corneal extracts also showed high ADH activities, by comparison with ovine and bovine samples. Moreover, the ADHs were distinct from the major liver isozymes in pI value and substrate specificity. 4. 4. Mammalian lens extracts exhibited significant ALDH activity of a form corresponding to the major liver cytosolic isozyme. Minor activity of the corneal enzyme was also observed in some species. 5. 5. Lens ADH phenotypes were species-specific, and consisted of either Class II activity (baboon and sheep), Class III ADH activity (pig), or activities of both ADH classes (cattle). 6. 6. Lens extracts also exhibited a complex pattern of ocular oxidase (EOX) activities following IEF. 7. 7. A role in peroxidatic aldehyde detoxification is proposed for these enzymes in anterior eye tissues.