Evidence for glycation of horse liver alcohol dehydrogenase in vivo

A procedure involving HPLC of N-phenylthiocarbamyl derivatives of N-(1-deoxyhexitolyl)amino acids was used to show that borohydride-treated alcohol dehydrogenase, from horse liver, contained 0.16 mol of N^ε-(1-deoxyhexitolyl) lysine per mol of enzyme. The identity of this compound was confirmed by mass spectrometry. It was concluded that glycation of alcohol dehydrogenase had occurred in vivo, resulting in the formation of N^ε-(1-deoxyfructosyl) lysyl residues. The presence of the latter accounted for the retention of 14% of the enzyme by an agaroseboronate gel. These findings are interesting in view of the observation [Tsai, C. S., and White, J. H. (1983) Biochem. J. 209, 309-314] that the enzyme was activated when it was glycated in vitro.