Structural characterization of the small molecular weight proteins present in UK101

UK101 (an acidic extract of goat liver at present under evaluation for human tumour immunotherapy) contains three major proteins of 10, 14 and 50 kDa, respectively. Biochemical analyses on this material gave the following results: 1) 50 kDa protein (UK150) is a glycoprotein containing mannose residues as shown by concanavalin A affinity chromatography. No further characterization has been performed, since its pharmacological activity has not been proved. 2) 14 kDa protein (UK114) shows a MW of 14290. The N-terminal of the protein is blocked. An internal sequence of 33 AA residues not so far described in the literature has been obtained by Edman degradation on CNBr segments. 3) The 10 kDa protein (UK110) shows an N-terminal sequence exactly identical to ubiquitin as to 38 AA residues. Mass spectometry experiments showed that UK110 was not homogeneous, but a mixture of ubiquitin and shorter forms of this molecule, lacking 2, 3 or 4 aminoacid residues from the C-terminus.