期刊
ANALYTICAL BIOCHEMISTRY
卷 362, 期 1, 页码 117-125出版社
ACADEMIC PRESS INC ELSEVIER SCIENCE
DOI: 10.1016/j.ab.2006.12.001
关键词
angiotensin-converting-enzyme; chemerin; peptide quantification; quantitative MALDI-TOF MS
Chemerin is a chemoattractive protein acting as a ligand for the G-protein-coupled receptor ChemR23/CMKLR1 and plays an important role in the innate and adaptive immunity. Proteolytic processing of its C terminus is essential for receptor binding and physiological activity. Therefore, we investigated the plasma stability of the decapeptide chemerin 145-154 (p(145-)F(154)) corresponding to the C terminus of the physiologically active chemerin variant E-21-F-154 from human hemofiltrate. For monitoring concentration-time profiles and degradation products we developed a novel matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry procedure using an internal peptide standard (hemorphin LVV-H7) for quantification. The linear range covers 2.5 orders of magnitude in the lower micromolar concentration range (lower limit of quantification 0.312 mu g/ml, 0.25 mu M) characterized by satisfactory reproducibility (CV <= 9%), accuracy (<= 10%), ruggedness, and recovery (98%). We found that chemerin 145-154 is C-terminally truncated in human citrate plasma by the cleavage of the penultimate dipeptidyl residue. N-terminal truncation was not observed. In contrast to citrate plasma, no degradation was detected in ethylenediammetetraacetate (EDTA) plasma. We identified angiotensin-converting-enzyme(ACE) to be responsible for C-terminal truncation, which could be completely inhibited by EDTA and captopril. These results are relevant to clarify the natural processing of chemerin and the potential involvement of ACE in mediating the immune response. (c) 2006 Elsevier Inc. All rights reserved.
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