title: Different effects of sulfur amino acids on prolidase and prolinase activity in normal and prolidase-deficient human erythrocytes.
abstract: BACKGROUND
  Prolidase and prolinase activity is known to be enhanced significantly in some diseases. Recently, the effect of amino acids on prolidase and prolinase activity in normal and prolidase-deficient human erythrocytes was investigated. It was reported that both enzymes were enhanced by glycine and alanine in the presence of MnCl(2).
  
  
  METHODS
  Erythrocytes were isolated from heparinized blood from normal human and a patient with prolidase deficiency. Effects of various sulfur amino acids on prolidase and prolinase activities against iminodipeptides in the presence of 1 or 0.1 mmol/l MnCl(2) were investigated.
  
  
  RESULTS
  Prolinase activity against prolylglycine in normal and prolidase-deficient erythrocyte lysates was inhibited by L-methionine, NAc-L-methionine and D,L-methionine in a concentration-dependent manner, but D-methionine enhanced the activity in low concentrations (0-20 mmol/l). D,L-Homocysteine inhibited the activity more strongly than other sulfur amino acids tested in a concentration-dependent manner. On the other hand, prolidase activity against glycylproline was enhanced by L-methionine, D-methionine, D,L-methionine, D,L-homocysteine thiolactone and D,L-ethionine. The rates of enhancement by these sulfur amino acids were in the following order: D,L-ethionine>D,L-methionine, D-methionine, D,L-homocysteine thiolactone>L-methionine (10 mmol/l).
  
  
  CONCLUSIONS
  The prolinase activity in normal and prolidase-deficient erythrocyte lysates was inhibited by L-methionine, D,L-ethionine and D,L-homocysteine. On the other hand, prolidase activity in their erythrocyte lysates was enhanced by D,L-ethionine, D-methionine and L-methionine. These results indicate the effects of these sulfur amino acids on prolidase and prolinase activities were different.
authors.affiliation: Department of Anesthesiology and Critical Care Medicine, Kochi Medical School, Nankoku-shi, Kochi 783-8505, Japan.
authors.forename: Mutsumi
authors.initials: M
authors.lastname: Uramatsu
authors.forename: Gang
authors.initials: G
authors.lastname: Liu
authors.forename: Soichiro
authors.initials: S
authors.lastname: Uramatsu
authors.forename: Mei
authors.initials: M
authors.lastname: Zhang
authors.forename: Weifang
authors.initials: W
authors.lastname: Wang
authors.forename: Kazuko
authors.initials: K
authors.lastname: Nakayama
authors.forename: Masanobu
authors.initials: M
authors.lastname: Manabe
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Kodama
mesh_terms: D000603:Amino Acids, Sulfur / Q000494:pharmacology*; D002712:Chlorides / Q000494:pharmacology*; D004150:Dipeptidases / Q000172:deficiency / Q000378:metabolism; D004912:Erythrocytes / Q000187:drug effects* / Q000378:metabolism; D006801:Humans; D066298:In Vitro Techniques; D007871:Leg Ulcer; D017895:Manganese Compounds / Q000494:pharmacology*
chemical_list: D000603:Amino Acids, Sulfur; D002712:Chlorides; D017895:Manganese Compounds; D004150:Dipeptidases; C022454:prolyl dipeptidase; C022449:proline dipeptidase; C025340:manganese chloride