title: The high alkaline fraction on isoelectric focusing of cerebrospinal fluid is cystatin C.
abstract: A high alkaline fraction with a pI of 9.2 is sometimes seen on isoelectric focusing patterns of cerebrospinal fluid. The appearance of this fraction mainly depends on the type of concentrators used to prepare the cerebrospinal fluid samples, prior to isoelectric focusing. The amino acid sequence of the high alkaline fraction showed sequence identity to cystatin C, a cysteine protease inhibitor with a pI of 9.2-9.3 and a molecular mass of 13.4 kDa. In addition, on Western blot the high alkaline fraction was recognized by an antibody, directed against cystatin C. Taken together, the present findings demonstrate that the high alkaline fraction is cystatin C.
authors.affiliation: Department of Clinical Chemistry, Leiden University Medical Centre, Netherlands. roelandse@rullf2.medfac.leidenuniv.nl
authors.forename: F W
authors.initials: FW
authors.lastname: Roelandse
authors.forename: R
authors.initials: R
authors.lastname: Amons
authors.forename: E P
authors.initials: EP
authors.lastname: ter Braak
authors.forename: R
authors.initials: R
authors.lastname: Nieuwland
authors.forename: J
authors.initials: J
authors.lastname: van Loon
authors.forename: J H
authors.initials: JH
authors.lastname: Souverijn
mesh_terms: D000595:Amino Acid Sequence; D002556:Cerebrospinal Fluid Proteins / Q000134:cerebrospinal fluid / Q000302:isolation & purification*; D055316:Cystatin C; D015891:Cystatins / Q000134:cerebrospinal fluid / Q000302:isolation & purification*; D006801:Humans; D007525:Isoelectric Focusing / Q000379:methods
chemical_list: C525030:CST3 protein, human; D002556:Cerebrospinal Fluid Proteins; D055316:Cystatin C; D015891:Cystatins