Malate dehydrogenases catalyzes the interconversion of malate to oxaloacetate. The enzyme DMSO reductase catalyzes the interconversion of DMSO and dimethylsulfide. More precisely, it facilitates the interconversion of glucose 1-phosphate and glucose 6-phosphate. The short timescale of interconversion precludes the separation of conformational isomers in most cases. Mercaptopurine interferes with nucleotide interconversion and glycoprotein synthesis. This ATP hydrolysis acts as a switch mediating interconversion of the protein between two states. Their interconversion requires either enzymatic or acid-base catalysis. The interconversion of chair conformers is called ring flipping or chair-flipping. Due to rapid interconversion, conformers are usually not isolable at room temperature. Basic solutions accelerate the interconversion of isomers. In living systems an enzyme, carbonic anhydrase, speeds the interconversion of CO and carbonic acid. Both isomers are unstable, and they undergo a slow interconversion. The interconversion of AMP and IMP occurs as part of the purine nucleotide cycle. The R-enantiomer undergoes extensive interconversion to the S-enantiomer "in vivo". The interconversion is catalyzed by base.