Reexamination of the cysteine residues in glucocerebrosidase.
Glucocerebrosidase, the deficient enzyme in Gaucher disease, catalyzes the cleavage of the beta-glycosidic linkage of glucosylceramide. A previous study on the enzyme identified three disulfide bridges and a single sulfhydryl [Lee, Y., Kinoshita, H., Radke, G., Weiler, S., Barranger, J.A. and Tomich, J.M. (1995) Position of the sulfhydryl group and the disulfide bonds of human glucocerebrosidase. J. Protein Chem. 14(3), 127-137] but recent publication of the X-ray structure identifies only two disulfide bridges with three free sulfhydryls [Dvir, H., Harel, M., McCarthy, A.A., Toker, L., Silman, I., Futerman, A.H. and Sussman, J.L. (2003) X-ray structure of human acid-beta-glucosidase, the defective enzyme in Gaucher disease. EMBO. 4(7), 704-709]. Using chemical modifications, acid cleavage and enzymatic digestion methods, we report that three free sulfhydryls exist and that the remaining four cysteines form two disulfide bonds located within the first 25 amino-terminal residues, supporting the X-ray structure.
Moharram
Ramy
R
Unit on Molecular Structures, Laboratory of Neurotoxicology, NIMH, NIH, DHHS, Bethesda, MD 20892, USA. moharrar@mail.nih.gov
Maynard
Dawn
D
Wang
Eric S
ES
Makusky
Anthony
A
Murray
Gary J
GJ
Martin
Brian M
BM
D000595:Amino Acid Sequence; D002851:Chromatography, High Pressure Liquid; D003545:Cysteine / Q000737:chemistry*; D005962:Glucosylceramidase / Q000737:chemistry*; D013058:Mass Spectrometry / Q000379:methods; D008969:Molecular Sequence Data; D011994:Recombinant Proteins / Q000737:chemistry
D011994:Recombinant Proteins; D005962:Glucosylceramidase; D003545:Cysteine