Purification of human wild-type or variant cystatin C from conditioned media of transfected cells.
The characterization of proteins in their native state is essential for the understanding of patho-genic isoforms. A variant of the cysteine protease inhibitor cystatin C is the major constituent of the amyloid deposited in the cerebral vasculature of patients with the Icelandic form of hereditary cerebral hemorrhage with amyloidosis (HCHWA-I). In order to study the nature of the bio-physical changes owing to the Leu68Gln substitution in cystatin C, we have developed a purification procedure of human cystatin C in its native state. The protein is isolated from media of stably transfected tissue culture cells using physiological conditions that preclude protein denaturation. The importance of mild purification conditions is underscored by the finding that denaturation of the wild-type and variant proteins facilitates a similar folding of both molecules, diminishing their differences in structure and biophysical properties. Following native purification conditions, variant cystatin C has a distinct structure compared to the wild-type protein.
Prelli
Frances
F
Department of Pathology, New York University School of Medicine, NY, USA.
Pawlik
Monika
M
Frangione
Blas
B
Levy
Efrat
E
D015153:Blotting, Western / Q000379:methods; D003001:Cloning, Molecular / Q000379:methods; D017077:Culture Media, Conditioned / Q000378:metabolism; D055316:Cystatin C; D015891:Cystatins / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism; D006801:Humans; D009154:Mutation; D020539:Sequence Analysis, Protein / Q000379:methods; D014162:Transfection / Q000379:methods
C525030:CST3 protein, human; D017077:Culture Media, Conditioned; D055316:Cystatin C; D015891:Cystatins