Amino acid sequence of tryptic fragments of glucoamylase G1 from Aspergillus niger

Abstract

The glycoprotein glucoamylase (EC 3.2.1.3) G1 from Aspergillus niger was digested with trypsin after 2-pyridylethylation and the resulting peptide fragments were separated by gel filtration followed by reverse phase HPLC. A different set of peptide fragments was obtained from the citraconylated, 2-pyridylethylated enzyme. These were separated by gel filtrations, affinity chromatography on Con A-Sepharose, and reverse phase HPLC. The amino acid sequence of the isolated peptide fragments was determined by automated Edman degradation and digestion with carboxypeptidases Y and B. The majority of the carbohydrate of glucoamylase G1 was located in a fragment which carried approximately 35 units of neutral sugar linked O-glycosidically to threonine and serine residues, while a minor fraction was located in a different tryptic fragment which contained a single N-glycosylated asparagine residue. © 1983 Carlsberg Laboratory.