TY - JOUR
T1 - The substrate specificity of isoamylase and the preparation of apo-glycogenin
AU - Lomako, Joseph
AU - Lomako, Wieslawa M.
AU - Whelan, William J.
N1 - Funding Information:
The author are pleased to dedicate this manuscript to Professor David J. Manners, our greatly esteemed colleague, who has made many important contributions to carbo-hydrate research. This work was supported by grants from the National Institutes of Health (DK37500), the Florida Affiliate of the American Heart Association and the Juvenile Diabetes Foundation International.
PY - 1992/4/6
Y1 - 1992/4/6
N2 - A new facet of the specificity of the glycogen-debranching enzyme, isoamylase, namely, the hydrolysis of a carbohydrate-amino acid linkage, is described. This bond joins the terminal, reducing-end D-glucose unit of glycogen to the hydroxyl group of tyrosine in glycogenin, the primer protein for glycogen biogenesis. The specificity was further defined by demonstrating that 4-nitrophenyl α-maltotrioside and higher homologs also act as substrates. The splitting of the glycogen-glycogenin bond by isoamylase indicates the α-anomeric configuration of the terminal D-glucose unit. It also provides a means of preparing apoglycogenin. Pullulanase, a somewhat similar starch- and glycogen-debranching enzyme, does not split these new isoamylase substrates, permitting the 4-nitrophenyl saccharides to be used in distinguishing between isoamylase and pullulanase.
AB - A new facet of the specificity of the glycogen-debranching enzyme, isoamylase, namely, the hydrolysis of a carbohydrate-amino acid linkage, is described. This bond joins the terminal, reducing-end D-glucose unit of glycogen to the hydroxyl group of tyrosine in glycogenin, the primer protein for glycogen biogenesis. The specificity was further defined by demonstrating that 4-nitrophenyl α-maltotrioside and higher homologs also act as substrates. The splitting of the glycogen-glycogenin bond by isoamylase indicates the α-anomeric configuration of the terminal D-glucose unit. It also provides a means of preparing apoglycogenin. Pullulanase, a somewhat similar starch- and glycogen-debranching enzyme, does not split these new isoamylase substrates, permitting the 4-nitrophenyl saccharides to be used in distinguishing between isoamylase and pullulanase.
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U2 - 10.1016/0008-6215(92)85082-B
DO - 10.1016/0008-6215(92)85082-B
M3 - Article
C2 - 1499031
AN - SCOPUS:0027113467
VL - 227
SP - 331
EP - 338
JO - Carbohydrate Research
JF - Carbohydrate Research
SN - 0008-6215
IS - C
ER -