OCULAR LENS NAD KINASE - PARTIAL-PURIFICATION AND METABOLIC IMPLICATIONS

The ocular lens displays a significant amount of NADP(PI) dependent me tabolic traffic, but the origin of this cofactor has not been establis hed. Size exclusion chromatography of bovine lens crude extract on a S ephacryl S300-HR column fitted with are eluate concentrator revealed t wee bands with NAD kinase activity, based on enzymatic cycling with si gnal amplification of the column fractions using a Cobas-Fara II centr ifugal fast analyzer. V-e/V-o ratios from the chromatographic runs sug gest that the relative molecular weight values lie within the ranges 8 .91-3.98 x 10(5) and 2.04-1.26 x 10(5), respectively, for these two ba nds. An similar to 10-fold enhancement of enzyme activity over the cru de fraction is realized from the chromatography step. Results point to NAD kinase as the source generator of this anchoring and linking cofa ctor for the oxidative stress and pentose phosphate enzyme systems, re spectively. (C) 1998 Academic Press.