The substrate specificity of isoamylase and the preparation of apo-glycogenin

J. Lomako, W. M. Lomako, William J. Whelan

Research output: Contribution to journalArticle

21 Citations (Scopus)

Abstract

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.

Original languageEnglish
Pages (from-to)331-338
Number of pages8
JournalCarbohydrate Research
Volume227
DOIs
StatePublished - Apr 6 1992

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Isoamylase
Substrate Specificity
Glycogen Debranching Enzyme System
Glycogen
Substrates
Glucose
Starch
Hydroxyl Radical
Tyrosine
Hydrolysis
Carbohydrates
Amino Acids
glycogenin
Proteins

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Organic Chemistry

Cite this

The substrate specificity of isoamylase and the preparation of apo-glycogenin. / Lomako, J.; Lomako, W. M.; Whelan, William J.

In: Carbohydrate Research, Vol. 227, 06.04.1992, p. 331-338.

Research output: Contribution to journalArticle

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