| 摘要 |
<p>In an enzymatically inactive, immunologically active beta -galactosidase mutein, at least one amino acid in the natural sequence in the region between amino acids 430 and 550 is replaced by another amino acid, and the enzymatic activity is not more than 1% of that of the native enzyme. For the genetic engineering preparation of a beta -galactosidase mutein of this type, the DNA sequence in a plasmid coding for beta -galactosidase is altered by site-directed mutagenesis in such a way that, after expression, at least one amino acid in the region between amino acids 430 and 550 of the protein is replaced by another one. An enzymatically inactive, immunologically active beta -galactosidase mutein of this type is used in the immunological determination of serum proteins on the enzyme immunoassay (EIA) principle using the enzyme beta -galactosidase as labelling enzyme to trap anti- beta -galactosidase antibodies or other binding proteins directed at beta -GAL, any of which may falsify the assay result. <IMAGE> </p> |
