Nitrile hydratase
Provided is an improved nitrile hydratase with improved catalytic activity. Also provided are DNA for coding the improved nitrile hydratase, a recombinant vector that contains the DNA, a transformant that contains the recombinant vector, nitrile hydratase acquired from a culture of the transformant, and a method for producing the nitrile hydratase. Also provided is a method for producing an amide compound that uses the culture or a processed product of the culture. The improved nitrile hydratase contains an amino acid sequence represented by SEQ ID NO: 50 (GX 1 X 2 X 3 X 4 DX 5 X 6 R) in a beta subunit, and is characterized in that X 4 is an amino acid selected from a group comprising cysteine, aspartic acid, glutamic acid, histidine, isoleucine, lysine, methionine, asparagine, proline, glutamine, serine and threonine.
1. A modified Rhodococcus bacterial or Nocardia bacterial nitrile hydratase, comprising in the α subunit,
b) an amino-acid sequence as shown in SEQ ID NO: 132:
AX 1 X 2 X 3 X 4 GX 5 X 6 GX 7 Q,
(SEQ ID NO: 132)
wherein
A is alanine,
G is glycine,
Q is glutamine,
wherein X 1 is M (methionine), X 2 is A (alanine), X 3 is S (serine), X 4 is L (leucine), X 5 is Y (tyrosine), X 6 is A (alanine), and
X 7 is substituted with an amino acid different from that in a wild type.
2. The modified Rhodococcus bacterial or Nocardia bacterial nitrile hydratase according to claim 1 , wherein X 7 is an amino acid selected from the group consisting of cysteine, phenylalanine, histidine, isoleucine, lysine, methionine, glutamine, arginine, threonine and tyrosine.
3. The modified Rhodococcus bacterial or Nocardia bacterial nitrile hydratase according to claim 1 , further comprising an amino-acid sequence in SEQ ID NO: 131 comprising the amino-acid sequence in SEQ ID NO: 132.
4. A DNA encoding the modified Rhodococcus bacterial or Nocardia bacterial nitrite hydratase according to claim 1 .
5. A recombinant vector, comprising the DNA according to claim 4 .
6. A transformant, comprising the recombinant vector according to claim 5 .
7. A nitrile hydratase collected from a culture obtained by incubating the transformant according to claim 6 .
8. A method for producing a nitrile hydratase, the method comprising:
incubating the transformant according to claim 6 ; and
collecting the nitrile hydratase from the obtained culture.
9. A method for producing an amide compound, the method comprising contacting a nitrile compound with a culture, or a processed product of the culture, obtained by incubating the nitrile hydratase according to claim 1 .