title: Monoclonal Antibody RYSK173 Recognizes the Dinuclear Zn Center of Serum Carnosinase 1 (CN-1): Possible Consequences of Zn Binding for CN-1 Recognition by RYSK173.
abstract: OBJECTIVE
  The proportion of serum carnosinase (CN-1) recognized by RYSK173 monoclonal antibody negatively correlates with CN-1 activity. We thus hypothesized that the epitope recognized by RYSK173 is accessible only in a catalytically incompetent conformation of the zinc dependent enzyme and we mapped its position in the CN-1 structure. Since patients with kidney failure are often deficient in zinc and other trace elements we also assessed the RYSK173 CN-1 proportion in serum of these patients and studied the influence of hemodialysis hereon in relation to Zn2+ and Cu2+ concentration during hemodialysis.
  
  
  RESULTS
  Epitope mapping using myc-tagged CN-1 fragments and overlapping peptides revealed that the RYSK173 epitope directly contributes to the formation of the dinuclear Zn center in the catalytic domain of homodimeric CN-1. Binding of RYSK173 to CN-1 was however not influenced by addition of Zn2+ or Cu2+ to serum. In serum of healthy controls the proportion of CN-1 recognized by RYSK173 was significantly lower compared to end-stage renal disease (ESRD) patients (1.12 ± 0.17 vs. 1.56 ± 0.40% of total CN-1; p<0.001). During hemodialysis the relative proportion of RYSK173 CN-1 decreased in parallel with increased serum Zn2+ and Cu2+ concentrations after dialysis.
  
  
  CONCLUSIONS
  Our study clearly indicates that RYSK173 recognizes a sequence within the transition metal binding site of CN-1, thus supporting our hypothesis that metal binding to CN-1 masks the epitope. The CN-1 RYSK173 proportion appears overall increased in ESRD patients, yet it decreases during hemodialysis possibly as a consequence of a relative increase in transition metal bound enzyme.
authors.affiliation: Vth Department of Medicine (Nephrology/Endocrinology/Rheumatology), University Medical Center Mannheim, University of Heidelberg, Mannheim, Germany.|Department of Endocrinology, The first affiliated hospital of Anhui Medical University, Hefei, China.
authors.forename: Shiqi
authors.initials: S
authors.lastname: Zhang
authors.affiliation: Department of Anesthesiology and Surgical Intensive Care Medicine, University Medical Center Mannheim, University of Heidelberg, Mannheim, Germany.
authors.forename: Holger A
authors.initials: HA
authors.lastname: Lindner
authors.affiliation: Vth Department of Medicine (Nephrology/Endocrinology/Rheumatology), University Medical Center Mannheim, University of Heidelberg, Mannheim, Germany.
authors.forename: Sarah
authors.initials: S
authors.lastname: Kabtni
authors.affiliation: Department of Nephrology, University Medical Center Groningen, University of Groningen, Groningen, the Netherlands.
authors.forename: Jaap
authors.initials: J
authors.lastname: van den Born
authors.affiliation: Department of Nephrology, University Medical Center Groningen, University of Groningen, Groningen, the Netherlands.
authors.forename: Stephan
authors.initials: S
authors.lastname: Bakker
authors.affiliation: Department of Nephrology, University Medical Center Groningen, University of Groningen, Groningen, the Netherlands.
authors.forename: Gerjan
authors.initials: G
authors.lastname: Navis
authors.affiliation: Vth Department of Medicine (Nephrology/Endocrinology/Rheumatology), University Medical Center Mannheim, University of Heidelberg, Mannheim, Germany.
authors.forename: Bernard
authors.initials: B
authors.lastname: Krämer
authors.affiliation: Vth Department of Medicine (Nephrology/Endocrinology/Rheumatology), University Medical Center Mannheim, University of Heidelberg, Mannheim, Germany.
authors.forename: Benito
authors.initials: B
authors.lastname: Yard
authors.affiliation: Vth Department of Medicine (Nephrology/Endocrinology/Rheumatology), University Medical Center Mannheim, University of Heidelberg, Mannheim, Germany.
authors.forename: Sibylle
authors.initials: S
authors.lastname: Hauske
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology* / Q000494:pharmacology; D001665:Binding Sites / Q000276:immunology; D019556:COS Cells; D020134:Catalytic Domain / Q000502:physiology; D002460:Cell Line; D002522:Chlorocebus aethiops; D003300:Copper / Q000097:blood / Q000378:metabolism*; D004150:Dipeptidases / Q000097:blood / Q000235:genetics / Q000276:immunology*; D018604:Epitope Mapping; D000939:Epitopes / Q000276:immunology*; D005260:Female; D014644:Genetic Variation / Q000235:genetics; D061307:Human Umbilical Vein Endothelial Cells; D006801:Humans; D007676:Kidney Failure, Chronic / Q000473:pathology; D008297:Male; D008875:Middle Aged; D006435:Renal Dialysis; D015032:Zinc / Q000097:blood / Q000276:immunology / Q000378:metabolism*
chemical_list: D000911:Antibodies, Monoclonal; D000939:Epitopes; C000609289:monoclonal antibody RYSK173; D003300:Copper; C522928:CNDP1 protein, human; D004150:Dipeptidases; D015032:Zinc