The high alkaline fraction on isoelectric focusing of cerebrospinal fluid is cystatin C

• Published in: Journal of the neurological sciences 1998-04, Vol.157 (1), p.105-108
• Main Authors: Roelandse, Freek W.C, Amons, Reinout, ter Braak, Emile P, Nieuwland, Rienk, van Loon, Jenny, Souverijn, John H.M
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Amino acid sequencing; Biological and medical sciences; Cerebral circulation. Blood-brain barrier. Choroid plexus. Cerebrospinal fluid. Circumventricular organ. Meninges; Cerebrospinal Fluid Proteins - cerebrospinal fluid; Cerebrospinal Fluid Proteins - isolation & purification; CSF; Cystatin C; Cystatins; Cystatins - cerebrospinal fluid; Cystatins - isolation & purification; Fundamental and applied biological sciences. Psychology; HAF; Humans; Isoelectric focusing; Isoelectric Focusing - methods; Vertebrates: nervous system and sense organs; γ-Trace protein
• ISSN: 0022-510X; 1878-5883
• DOI: 10.1016/S0022-510X(98)00055-0

A high alkaline fraction with a p I 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 p I 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.