Efficient production from Aspergillus niger of a heterologous protein and an individual protein domain, heavy isotope-labelled, for structure-function analysis

Aspergillus niger has been used successfully to secrete proteins labelled with C-13 and/or N-15 to a specific activity of > 99% for high resolution NMR analysis. In the case of a heterologous protein, hen egg-white lysozyme, N-15 single-labelled and C-13,N-15 double-labelled forms were secreted at yields of 100-200 mg l(-1) by optimising the type of carbon source used and the ratio of carbon to nitrogen. Another protein, the glucoamylase starch-binding domain from A. niger, was also produced as the N-15 single-labelled form at 20-40 mg l(-1).