Only sphingolipid activator protein B (SAP‐B or saposin B) stimulates the degradation of globotriaosylceramide by recombinant human lysosomal α‐galactosidase in a detergent‐free liposomal system

FEBS Letters

Kase, Ryoichi³  Sandhoff, Konrad¹  Klein, Andreas¹  Suzuki, Minoru²  Bierfreund, Uwe¹  Itoh, Kohji³  Hashimoto, Yasuhiro²  Kolter, Thomas¹  Sakuraba, Hitoshi³ 

[1] Institut für Organische Chemie und Biochemie der Universität Bonn, Gerhard-Domagk-Str. 1, D-53121 Bonn, Germany;Department of Membrane Biochemistry, The Tokyo Metropolitan Institute of Medical Science, 18–22, Honkomagome-3, Bunkyo-ku, Tokyo 113, Japan;Department of Clinical Genetics, The Tokyo Metropolitan Institute of Medical Science, 18–22, Honkomagome-3, Bunkyo-ku, Tokyo 113, Japan

关键词: Sphingolipid activator protein B;    Saposin B;    α-Galactosidase;    Globotriaosylceramide;    Cer;    ceramide or N-acylsphingosine;    GbOse3Cer;    globotriaosylceramide;    Galα1–4Galβ1–4Glcβ1-1Cer;    GM1;    Galβ1–3GalNAcβ1–4Gal(3-2αNeuAc)β1–4Glcβ1-1Cer;    LacCer;    lactosylceramide;    Galβ1–4Glcβ1-1Cer;    MALDI/TOF/MS;    matrix-assisted laser desorption ionization time-of-flight mass spectrometry;    SAP-A;    -B;    -C;    -D;    sphingolipid activator protein A;    B;    C;    D or saposin A;    B;    C;    D;    SAPs;    sphingolipid activator proteins;   

DOI  :  10.1016/0014-5793(96)00863-0

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

The degradation of globotriaosylceramide (GbOse₃Cer) by insect-cell derived recombinant human α-galactosidase (EC 3.2.1.22) was carried out in a detergent-free liposomal system in order to mimic intralysosomal conditions. GbOse₃Cer incorporated into unilamellar liposomes was used as the substrate, and naturally occurring sphingolipid activator proteins, rather than detergents, were used to stimulate the enzyme reaction. The degradation of GbOse₃Cer was dependent on the presence of both α-galactosidase and sphingolipid activator protein B (SAP-B or saposin B). It proceeded optimally at pH 4.6, and was enhanced by increasing amounts of both α-galactosidase (0.24–24 mU/50 μl assay) and SAP-B (0–5 μg/50 μl assay). The enzyme reaction was not affected by SAP-A, SAP-C, or SAP-D. Therefore, our results indicate that only SAP-B is essential for the degradation of GbOse₃Cer by α-galactosidase.

【 授权许可】

Unknown