Aldehyde and aldose reductases from human placenta. Heterogeneous expression of multiple enzyme forms

• Published in: The Journal of biological chemistry Vol. 265; no. 19; pp. 10912 - 10918
• Main Authors: VANDER JAGT, D. L, HUNSAKER, L. A, ROBINSON, B, STANGEBYE, L. A, DECK, L. M
• Format: Journal Article
• Language: English
• Published: Bethesda, MD American Society for Biochemistry and Molecular Biology 05.07.1990
• Subjects: Alcohol Dehydrogenase - antagonists & inhibitors; Alcohol Dehydrogenase - isolation & purification; Alcohol Dehydrogenase - metabolism; Aldehyde Reductase - antagonists & inhibitors; Aldehyde Reductase - isolation & purification; Aldehyde Reductase - metabolism; Analytical, structural and metabolic biochemistry; Biological and medical sciences; Chromatography, High Pressure Liquid; Dithiothreitol - pharmacology; Electrophoresis, Polyacrylamide Gel; Enzymes and enzyme inhibitors; Female; Fundamental and applied biological sciences. Psychology; Glyceraldehyde - metabolism; Humans; Hydrogen-Ion Concentration; Imidazoles - pharmacology; Imidazolidines; Immunoenzyme Techniques; Kinetics; NADP - pharmacology; Naphthalenes - pharmacology; Oxidoreductases; Phthalazines - pharmacology; Placenta - enzymology; Pregnancy; Substrate Specificity; Sugar Alcohol Dehydrogenases - metabolism; Human; Purification; Enzymatic activity; Aldose reductase; Affinity chromatography; Enzyme; Alcohol dehydrogenase (NADP+); Immunochemistry; Chromatofocusing
• DOI: 10.1016/S0021-9258(19)38533-3
• ISSN: 0021-9258

Aldehyde reductase (ALR1) and aldose reductase (ALR2) were purified from human placenta by a rapid and efficient scheme that included rapid extraction of both reductases from 100,000 x g supernatant material with Red Sepharose followed by purification by chromatofocusing on Pharmacia PBE 94 and then chromatography on a hydroxylapatite high performance liquid chromatography column. Expression of ALR1 and ALR2 in placenta is variable with ALR1/ALR2 ratios ranging from 1:4 to 4:1. ALR1 and ALR2 are immunochemically distinct. ALR1 shows broad specificity for aldehydes but does not efficiently catalyze the reduction of glucose due to poor binding (Km = 2.5 M). ALR1 exhibits substrate inhibition with many substrates. ALR2 also shows broad specificity for aldehydes. Although glucose is a poor substrate for ALR2 compared with other substrates, the affinity of ALR2 for glucose (Km = 70 mM) suggests that glucose can be a substrate under hyperglycemic conditions. ALR2 shows normal hyperbolic kinetics with most substrates except with glyceraldehyde, which exhibits substrate activation. Treatment of ALR2 with dithiothreitol converted it into a form that exhibited hyperbolic kinetics with glyceraldehyde. Dithiothreitol treatment of ALR2 did not alter its properties toward other substrates or affect its inhibition by aldose reductase inhibitors such as sorbinil (2,4-dihydro-6-fluorospiro-[4H-1-benzopyran-4,4'-imidazolidine]-2' ,5'- dione), tolrestat (N-[[6-methoxy-5-(trifluoromethyl)-1-naphthalenyl]thioxomethyl]-N- methylglycine), or statil (3-[(4-bromo-2-fluorophenyl)methyl]-3,4-dihydro-4-oxo-1-phthalazineac etic acid).