Abstract: The disclosure provides a fluorescent sensor, comprising a) a responsive polypeptide, and b) an optically active polypeptide, wherein the optically active polypeptide is inserted into the responsive polypeptide. The present disclosure also relates to a nucleic acid sequence encoding the fluorescent sensor according to any embodiment, or a complementary sequence thereof. The disclosure also provides an expression vector comprising the nucleic acid sequence or a complementary sequence thereof of the disclosure operably linked to an expression control sequence. The disclosure also provides a cell containing the expression vector of the disclosure. The present disclosure also provides a method for preparing the fluorescent sensor of this disclosure, comprising the following steps: providing a host cell comprising an expression vector that expresses the fluorescent sensor of the disclosure, culturing the host cell under conditions suitable for the expression of the host cell, and separating the fluorescent sensor.

Abstract: Provided is an arginine fluorescent probe, comprising a polypeptide B that responds to arginine and a fluorescent protein A that expresses arginine; the fluorescent protein A is inserted into the polypeptide B, B is divided into an upper structural part and a lower structural part, B1 and B2, and a probe structure represented by the formula B1-A-B2 is formed; optimized mutants are likewise obtained by truncation and site-directed mutagenesis at different positions, and specific binding of the polypeptide B and arginine leads to a change in the fluorescence signal of the fluorescent protein A; and the polypeptide B is an arginine binding protein or a mutant thereof.

Abstract: Disclosed is a tryptophan optical probe, a preparation method therefor and the use thereof. Disclosed is an optical probe, comprising a tryptophan-sensitive polypeptide or a functional variant thereof and an optically active polypeptide or a functional variant thereof, wherein the optically active polypeptide or the functional variant thereof is located in the sequence of the tryptophan-sensitive polypeptide or the functional variant thereof. Furthermore, disclosed are a method for preparing the above-mentioned probe and the use thereof in the detection of tryptophan.