Hamamatsu-Photonics K.k.

Sunao Hisada

Kenichi Kasai

Hiroyuki Matsumoto

Kiyohito Shimura

Yukiko Ito

Disclosed is an isolated polynucleotide encoding a modified Fab' antibody, which includes an Fd chain and an L chain with the Fd chain including a CH1 region and the L chain including a CL region, wherein the modified Fab' antibody further includes a cysteine for binding to a fluorescent dye, and the polynucleotide includes an Fd chain coding region and an L chain coding region linked therebetween in a manner that will allow expression of the modified Fab' antibody. Also disclosed are an expression vector containin the isolated polynucleotide, an isolated transformed host cell containing the expression vector, and a cell culture including the transformed host cell.

Isolated Polynucleotide encoding modified fab' antibody, expression vector, and transformed host cell

A method for quantitatively detecting an antigen which comprises (1) a first step of providing an Fab' antibody having a uniform isoelectric point, said antibody forming an immune complex with an antigen in an analytical sample and being modified by adding an amino acid sequence comprising a charged amino acid residue and by being labeled with a fluorescent dye, (2) a second step of mixing the Fab&#x2032; antibody having a uniform isoelectric point with the analytical sample containing the antigen to obtain a mixture comprising the immune complex, (3) a third step of separating the mixture by performing electrophoresis in a carrier, (4) a fourth step of irradiating an excitation light which excites the fluorescent dye to the mixture separated in the third step to cause fluorescence in the immune complex, and (5) a fifth step of detecting the fluorescence.

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Shizuoka, Japan

Sunao Hisada