Anserine inhibits carnosine degradation but in human serum carnosinase (CN1) is not correlated with histidine dipeptide concentration.
BACKGROUND
We reported an association of a particular allele of the carnosinase (CNDP1 Mannheim) gene with reduced serum carnosinase (CN1) activity and absence of nephropathy in diabetic patients. Carnosine protects against the adverse effects of high glucose levels but serum carnosine concentration was generally low.


METHODS
We measured the concentration of two further histidine dipeptides, anserine and homocarnosine, via HPLC. CN1 activity was measured fluorometically and for concentration we developed a capture ELISA.


RESULTS
We found an association between the CNDP1 Mannheim allele and reduced serum CN1 activity for all three dipeptides but no correlation to serum concentrations although anserine and homocarnosine inhibited carnosinase activity. Patients with liver cirrhosis have low CN1 activity (0.24 ± 0.17 μmol/ml/h, n=7 males; normal range: 3.2 ± 1.1, n=104; p<0.05) and CN1 concentrations (2.3 ± 1.5 μg/ml; normal range: 24.9 ± 8.9, p<0.05) but surprisingly, histidine dipeptide concentrations in serum are not increased compared to controls.


CONCLUSIONS
Serum histidine dipeptide concentrations are not correlated to CN1 activity. The protective effect of low CN1 activity might be related either to turnover of CN1 substrates or a protective function of dipeptides might be localized in other tissues.
Peters
Verena
V
Centre for Paediatric and Adolescent Medicine, University of Heidelberg, Division of Metabolic Diseases, Heidelberg, Germany. Verena.Peters@med.uni-heidelberg.de
Jansen
Erwin E W
EE
Jakobs
Cornelis
C
Riedl
Eva
E
Janssen
Bart
B
Yard
Benito A
BA
Wedel
Johannes
J
Hoffmann
Georg F
GF
Zschocke
Johannes
J
Gotthardt
Daniel
D
Fischer
Christine
C
Köppel
Hannes
H
D000328:Adult; D000861:Anserine / Q000097:blood / Q000378:metabolism*; D002336:Carnosine / Q000097:blood / Q000378:metabolism*; D004150:Dipeptidases / Q000378:metabolism*; D005260:Female; D006639:Histidine / Q000097:blood / Q000378:metabolism*; D006801:Humans; D008103:Liver Cirrhosis / Q000097:blood / Q000201:enzymology / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D055815:Young Adult
D006639:Histidine; D002336:Carnosine; C522928:CNDP1 protein, human; D004150:Dipeptidases; D000861:Anserine