A method for preparing a biologically active complex, said method comprising arecombinant protein having thesequence of .alpha.-lactalbumin, such as human .alpha.- lactalbumin or afragment thereof but which lacks intra-molecular disulfide bonds,and oleic acid, and process for preparing this are described and claimed. Therecombinant protein suitably has cysteines found inthe native protein changed to other amino acids, such as alanine. Improvementsin recombinant expression, process rationalisationand yields of biologically active complexes, as well as the complexes obtainedare also described and claimed.
