title: Molecular and practical aspects of the enzymatic properties of human serum albumin and of albumin-ligand complexes.
abstract: BACKGROUND
  Human serum albumin and some of its ligand complexes possess enzymatic properties which are useful both in vivo and in vitro.
  
  
  METHODS
  This review summarizes present knowledge about molecular aspects, practical applications and potentials of these properties.
  
  
  CONCLUSIONS
  The most pronounced activities of the protein are different types of hydrolysis. Key examples are esterase-like activities involving Tyr411 or Lys199 and the thioesterase activity of Cys34. In the first case, hydrolysis involves water and both products are released, whereas in the latter cases one of the products is set free, and the other stays covalently bound to the protein. However, the modified Cys34 can be converted back to its reduced form by another compound/enzymatic system. Among the other activities are glucuronidase, phosphatase and amidase as well as isomerase and dehydration properties. The protein has great impact on the metabolism of, for example, eicosanoids and xenobiotics. Albumin with a metal ion-containing complex is capable of facilitating reactions involving reactive oxygen and nitrogen species.
  
  
  CONCLUSIONS
  Albumin is useful in detoxification reactions, for activating prodrugs, and for binding and activating drug conjugates. The protein can be used to construct smart nanotubes with enzymatic properties useful for biomedical applications. Binding of organic compounds with a metal ion often results in metalloenzymes or can be used for nanoparticle formation. Because any compound acting as cofactor and/or the protein can be modified, enzymes can be constructed which are not naturally found and therefore can increase, often stereospecifically, the number of catalytic reactions. This article is part of a Special Issue entitled Serum Albumin.
authors.affiliation: Department of Biomedicine, University of Aarhus, DK-8000 Aarhus C, Denmark. Electronic address: ukh@biokemi.au.dk.
authors.forename: Ulrich
authors.initials: U
authors.lastname: Kragh-Hansen
mesh_terms: D004950:Esterases / Q000737:chemistry / Q000378:metabolism*; D006801:Humans; D008024:Ligands; D011487:Protein Conformation; D012709:Serum Albumin / Q000737:chemistry / Q000378:metabolism*
chemical_list: D008024:Ligands; D012709:Serum Albumin; D004950:Esterases
keywords: Detoxification reactions; Esterase-like activity; Human serum albumin; Hydrolysis; Metalloenzymes; Prodrug activation