Abstract: The present invention provides a method for producing a compound library comprising two or more cyclic compounds represented by the formula (I), comprising a step of allowing a macrocyclase in vitro to act on two or more peptides represented by the formula (II): LP-X—(Xa)m-Y—Z (II) wherein X represents a group represented by the formula (1), Y is a peptide residue consisting of four amino acids and/or analogs thereof and contains a group represented by the formula (2) (wherein R1 and B1 are as defined above, and R3 represents a hydrogen or a hydrocarbon group), and LP is present or absent and, when present, represents a peptide residue consisting of 1 to 100 amino acids and/or analogs thereof, and forming the nitrogen-containing 6-membered ring A while eliminating LP, if present, to form the two or more cyclic compounds represented by the formula (I).

Abstract: Disclosed is a method for quantifying L-tryptophan involving a step for mixing a specimen, L-tryptophan oxidase, and water, a step for allowing the obtained reaction solution to stand a predetermined period of time in the presence of oxygen, and a step for measuring the reaction product resulting from action of enzymes present in the reaction solution after allowing to stand. The L-tryptophan oxidase has a given amino acid sequence and has oxidase activity that generates hydrogen peroxide and ammonia by acting on the L-tryptophan in the presence of oxygen and water. The oxidase activity of the L-tryptophan oxidase on the L-phenylalanine is in the range of 0-3% of the oxidase activity thereof on the L-tryptophan, and the L-tryptophan oxidase does not have oxidase activity on protein-constituting amino acids other than L-tryptophan and L-phenylalanine. Also disclosed are a kit used to quantify the L-tryptophan containing L-tryptophan oxidase, and an enzyme sensor using the L-tryptophan oxidase.

Abstract: Disclosed is a method for quantifying L-tryptophan involving a step for mixing a specimen, L-tryptophan oxidase, and water, a step for allowing the obtained reaction solution to stand a predetermined period of time in the presence of oxygen, and a step for measuring the reaction product resulting from action of enzymes present in the reaction solution after allowing to stand. Also disclosed are a kit used to quantify the L-tryptophan containing L-tryptophan oxidase, and an enzyme sensor using the L-tryptophan oxidase. This method, kit and enzyme sensor use an L-tryptophan-specific enzyme, so are capable of quantifying L-tryptophan even in the presence of other amino acids.

Abstract: Disclosed is a method for quantifying L-tryptophan involving a step for mixing a specimen, L-tryptophan oxidase, and water, a step for allowing the obtained reaction solution to stand a predetermined period of time in the presence of oxygen, and a step for measuring the reaction product resulting from action of enzymes present in the reaction solution after allowing to stand. The L-tryptophan oxidase has a given amino acid sequence and has oxidase activity that generates hydrogen peroxide and ammonia by acting on the L-tryptophan in the presence of oxygen and water. The oxidase activity of the L-tryptophan oxidase on the L-phenylalanine is in the range of 0-3% of the oxidase activity thereof on the L-tryptophan, and the L-tryptophan oxidase does not have oxidase activity on protein-constituting amino acids other than L-tryptophan and L-phenylalanine. Also disclosed are a kit used to quantify the L-tryptophan containing L-tryptophan oxidase, and an enzyme sensor using the L-tryptophan oxidase.