Homocysteine desulphurase from the protozoan trichomonas vaginalis

A method of assaying methionine, cysteine or O-acetyl-L-serine in a sample comprising the steps of:

• a) contacting the sample with recombinant protozoan homocysteine desulphurase or functionally active derivative thereof capable of degrading methionine, cysteine or O-acetyl-L-serine, and
• b) determining any reaction product(s) formed by enzyme degradation of methionine, cysteine or O-acetyl-L-serine.

A kit for diagnostic in vitro determination of a homocysteine level in a sample, wherein the kit comprises:

• a) an enzyme capable of degrading homocysteine, and
• b) means for enabling determination of reaction products produced by degradation of homocysteine by the enzyme.

A polynucleotide fragment encoding a protozoan homocysteine desulphurase.

A recombinant protozoan homocysteine desulphurase polypeptide or functionally active derivative thereof displaying homocysteine desulphurase activity.

A homocysteine desulphurase polypeptide having an amino acid sequence selected from SEQ ID NO:2, SEQ ID NO:4, SEQ ID NO:6, and SEQ ID NO:8 or a functionally active derivative thereof.

A method of assaying homocysteine in a sample, comprising:

• (a) contacting said sample with a homocysteine desulphurase enzyme, said homocysteine desulphurase having an amino acid sequence with at least 90% sequence similarity to a sequence selected from the group consisting of SEQ ID NO:2, SEQ ID NO:4, SEQ ID NO:6 and SEQ ID NO:8,
• (b) detecting the presence of at least one reaction product formed by the enzyme degradation of any homocysteine in said sample, wherein detection of said reaction product indicates said sample contained homocysteine.

A kit for diagnostic in vitro determination of a homocysteine level in a sample, wherein the kit comprises:

• (a) a homocysteine desulphurase enzyme having an amino acid sequence at least 90% similar to a sequence selected from the group consisting of SEQ ID NO:2, SEQ ID NO:4, SEQ ID NO:6 and SEQ ID NO:8, and
• (b) reagents to detect a reaction product formed by enzymatic degradation of homocysteine by said enzyme, said reaction product selected from the group consisting of α-ketobutyrate, hydrogen sulphide, and ammonia.

An isolated polynucleotide molecule encoding a protein having an amino acid sequence with at least 90% sequence similarity to a sequence selected from the group consisting of SEQ ID NO:1, SEQ ID NO:3, SEQ ID NO:5 and SEQ ID NO:7, and wherein said protein has homocysteine desulphurase activity.

A method of assaying homocysteine in a sample comprising the steps of:

• a) contacting the sample with an enzyme that catalyses the degradation of homocysteine, and
• b) determining any reaction product(s) formed by enzyme degradation of homocysteine by said enzyme.

A method of assaying methionine, cysteine or O-acetyl-L-serine in a sample comprising the steps of:

• a) contacting the sample with a protozoan homocysteine desulphurase or functionally active derivative thereof capable of degrading methionine, cysteine or O-acetyl-L-serine, and
• b) determining any reaction product(s) formed by enzyme degradation of methionine, cysteine or O-acetyl-L-serine.

A kit for diagnostic in vitro determination of a homocysteine level in a sample wherein the kit comprises:

• a) an enzyme that catalyses the degradation of homocysteine, and
• b) means for enabling determination of reaction products produced by degradation of homocysteine by the enzyme.

A polynucleotide fragment encoding a homocysteine desulphurase having at least 80% similarity with the fragment shown in SEQ ID No:1 or SEQ ID No:3.

A recombinant homocysteine desulphurase polypeptide having at least 80% similarity with the polypeptide shown in SEQ ID No:2, SEQ ID No:4, SEQ ID No:6 or SEQ ID No:8 or functionally active derivative thereof.