SEQUENCE OF PIG LENS ALDOSE REDUCTASE AND ELECTROSPRAY MASS-SPECTROMETRY OF NONCOVALENT AND COVALENT COMPLEXES

The complete sequence of pig lens aldose reductase (EC 1.1.1.21), a me mber of the nicotinamide coenzyme-dependent aldo-keto reductase super family, was determined by the combined use of data obtained from Edman degradation, fast-atom-bombardment mass spectrometry and electrospray mass spectrometry. The N-terminal residue of human and pig aldose red uctase was shown to be acetylated. The assignment of a disulfide bridg e (Cys298 - Cys303) was obtained by mass spectrometry. Electrospray ma ss spectrometry has been used for molecular mass measurement of human muscle (35758 +/- 7Da) and pig lens (35778 +/- 3Da) aldose reductase; using mild ionization conditions, it has also been used to study the r eversible interaction involved in a non-covalent complex with NADP+ (3 6527 +/- 4Da). An alkylating analog of NADP+ (3-chloroacetylpyridine-a denine dinucleotide phosphate) was used as an irreversible inhibitor t o investigate the NADP binding site and the mass of the covalent compl ex was measured (36521 +/- 3 Da).