title: Continuous monitoring of prostatic acid phosphatase using self-indicating substrates.
abstract: BACKGROUND
  The continuous measurement of acid phosphatase (EC 3.1.3.2) activity in serum represents an analytical task not yet sufficiently accomplished.
  
  
  METHODS
  Introducing two novel substrates-2-chloro-4-nitrophenyl phosphate (CNP-P), which was preferred, and 4-nitronaphthyl-1-phosphate (NN-P)-an alternative assay to measure enzymatic activity was developed and compared with a modification of Hillmann's method (azo coupling of released naphth-1-ol with a diazonium compound). Apart from different substrate concentrations of 2-chloro-4-nitrophenyl phosphate, 4 mmol/l, and naphthyl-1-phosphate (N-P), 8 mmol/l (with Fast Red TR, 5 mmol/l), respectively, following identical conditions were selected: Citrate, 50 mmol/l, pH 5.75; pentane-1,5-diol, 150 mmol/l; tartrate, 60 mmol/l; 37 degrees C.
  
  
  RESULTS
  Whereas intensity and stability of the azo dye unpredictably depend on the albumin concentration of the sample, the direct test with 2-chloro-4-nitrophenyl phosphate resisted sample interferences, showed no intrinsic hydrolysis by albumin, relied on stable reagents and proved superior in sensitivity, precision and ease of handling. In measuring prostatic phosphatase, the proposed procedure closely correlated with Hillmann's method. The preliminary 0.95-reference intervals for adults were 1.2-3.9 kU/l and 5.8-14.8 U/l for total activity, respectively.
  
  
  CONCLUSIONS
  The direct assay of the enzyme is suited as an economic, rapid and robust method for mechanized or manual use.
authors.affiliation: Institut für Klinische Chemie, Medizinische Universität zu Lübeck, Ratzeburger Allee 160, 23538 Lübeck, Germany.
authors.forename: Klaus
authors.initials: K
authors.lastname: Lorentz
mesh_terms: D000135:Acid Phosphatase; D001391:Azo Compounds / Q000737:chemistry / Q000378:metabolism; D006018:Glycols / Q000494:pharmacology; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008297:Male; D009281:Naphthalenes / Q000737:chemistry / Q000378:metabolism*; D009943:Organophosphorus Compounds / Q000737:chemistry / Q000378:metabolism*; D010420:Pentanes; D010710:Phosphates / Q000737:chemistry / Q000378:metabolism*; D017027:Protein Tyrosine Phosphatases / Q000097:blood*; D011933:Reagent Kits, Diagnostic; D012016:Reference Values; D015203:Reproducibility of Results; D012995:Solubility; D013053:Spectrophotometry / Q000379:methods; D013379:Substrate Specificity; D013644:Tartrates / Q000494:pharmacology
chemical_list: C474535:2-chloro-4-nitrophenyl phospahte; C474534:4-nitronaphthyl-1-phosphate; D001391:Azo Compounds; D006018:Glycols; D009281:Naphthalenes; D009943:Organophosphorus Compounds; D010420:Pentanes; D010710:Phosphates; D011933:Reagent Kits, Diagnostic; D013644:Tartrates; C578469:1,5-pentanediol; D000135:Acid Phosphatase; C428439:prostatic acid phosphatase; D017027:Protein Tyrosine Phosphatases; C029768:tartaric acid