The aminoterminal portion of cerebrospinal fluid cystatin C in hereditary cystatin C amyloid angiopathy is not truncated. Direct sequence analysis from agarose gel electropherograms

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T1 - The aminoterminal portion of cerebrospinal fluid cystatin C in hereditary cystatin C amyloid angiopathy is not truncated. Direct sequence analysis from agarose gel electropherograms

AU - Olafsson, I

AU - Gudmundsson, G

AU - Abrahamson, Magnus

AU - Jensson, O

AU - Grubb, Anders

PY - 1990

Y1 - 1990

N2 - The isolated amyloid substance in hereditary cystatin C amyloid angiopathy (HCCAA) is mainly composed of a cystatin C variant devoid of the 10 amino terminal amino acid residues of extracellular cystatin C from healthy individuals. We have developed a procedure for protein sequencing directly from agarose gel electropherograms and used this in conjunction with isoelectric focusing to investigate the amino terminal sequence of cerebrospinal fluid (CSF) cystatin C in HCCAA patients. The amino-terminal sequence determined for cystatin C from a HCCAA patient CSF sample, Xaa-Ser-Pro-Gly-Lys-Pro-Pro-Xaa-Leu-Val-Gly-Gly-Pro-Met-Xaa-Ala-Xaa-Val, showed that the protein was not amino-termi-nally truncated. CSF cystatin C from all nine HCCAA patients investigated was found to have an isoelectric point identical to that of native cystatin C, and the truncated form of cystatin C isolated from amyloid deposits was shown to contribute to less than 1 % of the total amount of cystatin C in CSF. The total cysteine proteinase inhibitory capacity of CSF from HCCAA patients was lower than that of CSF from other patients. This decreased CSF inhibitory capacity in HCCAA patients was caused by decreased levels of cystatin C, since the levels of the other two cysteine proteinase inhibitors found in CSF, oc2-macroglobulin and kininogen, were significantly higher than in CSF from non-HCCAA patients.

AB - The isolated amyloid substance in hereditary cystatin C amyloid angiopathy (HCCAA) is mainly composed of a cystatin C variant devoid of the 10 amino terminal amino acid residues of extracellular cystatin C from healthy individuals. We have developed a procedure for protein sequencing directly from agarose gel electropherograms and used this in conjunction with isoelectric focusing to investigate the amino terminal sequence of cerebrospinal fluid (CSF) cystatin C in HCCAA patients. The amino-terminal sequence determined for cystatin C from a HCCAA patient CSF sample, Xaa-Ser-Pro-Gly-Lys-Pro-Pro-Xaa-Leu-Val-Gly-Gly-Pro-Met-Xaa-Ala-Xaa-Val, showed that the protein was not amino-termi-nally truncated. CSF cystatin C from all nine HCCAA patients investigated was found to have an isoelectric point identical to that of native cystatin C, and the truncated form of cystatin C isolated from amyloid deposits was shown to contribute to less than 1 % of the total amount of cystatin C in CSF. The total cysteine proteinase inhibitory capacity of CSF from HCCAA patients was lower than that of CSF from other patients. This decreased CSF inhibitory capacity in HCCAA patients was caused by decreased levels of cystatin C, since the levels of the other two cysteine proteinase inhibitors found in CSF, oc2-macroglobulin and kininogen, were significantly higher than in CSF from non-HCCAA patients.

KW - agarose gel electrophoresis

KW - amino acid sequence analysis

KW - amyloidosis

KW - cerebral haemorrhage

KW - cystatin C

KW - cysteine proteinase inhibitor

U2 - 10.3109/00365519009091569

DO - 10.3109/00365519009091569

M3 - Article

VL - 50

SP - 85

EP - 93

JO - Scandinavian Journal of Clinical & Laboratory Investigation

JF - Scandinavian Journal of Clinical & Laboratory Investigation

SN - 1502-7686

IS - 1

ER -