Production of<sup>15</sup>N-labelled hen egg white lysozyme using Aspergillus niger
Roberts IN., MacKenzie DA., Jeenes DJ., Archer DB., Radford SE., Robinson CV., Aplin RT., Dobson CM.
Aspergillus niger has been used as a host organism for the production of15N-labelled hen egg white lysozyme (HEWL). In order to achieve maximum incorporation of label, strains expressing the HEWL gene were grown in medium containing ammonium15N chloride as sole nitrogen source. Yields of HEWL protein were reduced relative to those obtained on more complex media. Gains in yield using complex media were offset by reduction in15N incorporation. No differences in either yield or kinetics of production were observed when ammonium15N chloride was replaced by unlabelled ammonium chloride as sole nitrogen source. Yields of15N-HEWL produced in this way are adequate for, and offer considerable advantages to, NMR studies of structure and folding of mutant and wild-type lysozymes. © 1992 Kluwer Academic Publishers.