Truncated cystatin C in cerebrospiral fluid: Technical [corrected] artefact or biological process?
Cystatin C, a low molecular weight cysteine proteinase inhibitor present in human body fluids at physiological concentrations, is more expressed in cerebrospinal fluid (CSF) than in plasma. Mass spectrometric characterization showed that after 3 months of storage of human CSF at -20 degrees C, cystatin C was cleaved in the peptide bond between R8 and L9 and lost its eight N-termini amino acids, whereas this cleavage did not occur when stored at -80 degrees C. This truncation occurred in all CSF samples studied irrespective of the underlying neurological status, indicating a storage-related artefact rather than a physiological or pathological processing of the protein. These results stress the importance of optimal preanalytical storage conditions of any sample prior to proteomics studies.
Carrette
Odile
O
Biomedical Proteomics Research Group, Geneva University Hospital and Medical School, 1 rue Michel Servet, CH-1211 Geneva 4, Switzerland. Odile.Carrette@medecine.unige.ch
Burkhard
Pierre R
PR
Hughes
Severine
S
Hochstrasser
Denis F
DF
Sanchez
Jean-Charles
JC
D016477:Artifacts; D055316:Cystatin C; D015891:Cystatins / Q000134:cerebrospinal fluid* / Q000737:chemistry*; D015853:Cysteine Proteinase Inhibitors / Q000737:chemistry; D004591:Electrophoresis, Polyacrylamide Gel; D006801:Humans; D013058:Mass Spectrometry / Q000379:methods; D040081:Protein Array Analysis; D017434:Protein Structure, Tertiary; D011506:Proteins / Q000737:chemistry; D040901:Proteomics / Q000379:methods; D013048:Specimen Handling; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D013696:Temperature; D013997:Time Factors
C525030:CST3 protein, human; D055316:Cystatin C; D015891:Cystatins; D015853:Cysteine Proteinase Inhibitors; D011506:Proteins