Xylose isomerase with improved properties
First Claim
1. An isolated nucleic acid encoding a polypeptide comprising an amino acid sequence encoded by SEQ. ID. No. 1,wherein nnn at nucleotides 487-489 of SEQ. ID. No. 1 encodes any amino acid, and nnn at nucleotides 1114-1116 of SEQ. ID. No. 1 encodes any nucleotide except glutamic acid, and wherein said polypeptide has at least 10% higher specific xylose isomerase activity than a xylose isomerase encoded by SEQ ID No. 2.
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Abstract
The present invention relates to novel nucleic acid sequences which, upon expression in a procaryotic or eucaryotic cell, code for a polypeptide having an elevated specific xylose isomerase activity compared to the wildtype Thermus thermophilus xylose isomerase. They are selected from a) nucleic acid sequences shown in SEQ. ID. No 1; b) the complementary strand of the sequence defined in (a) above; c) nucleic acid sequences which hybridize to the sequences defined in (a) or (b) above; d) nucleic acid sequences which, but for the degeneracy of the genetic code, would hybridize to the sequences defined in (a), (b) or (c) above and which code for the same polypeptide as those defined in (a), (b) or (c) above. The present invention further provides a process of producing ethanol from xylose containing materials comprising contacting cells that express such nucleic acid sequences and novel modified xylose isomerases that advantageously can be applied in the production of fructose syrups.
70 Citations
29 Claims
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1. An isolated nucleic acid encoding a polypeptide comprising an amino acid sequence encoded by SEQ. ID. No. 1,
wherein nnn at nucleotides 487-489 of SEQ. ID. No. 1 encodes any amino acid, and nnn at nucleotides 1114-1116 of SEQ. ID. No. 1 encodes any nucleotide except glutamic acid, and wherein said polypeptide has at least 10% higher specific xylose isomerase activity than a xylose isomerase encoded by SEQ ID No. 2.
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15. An isolated nucleic acid having a nucleotide sequence that is at least 85%, but less than 100%, identical to the nucleotide sequence of SEQ. ID. No. 2,
wherein said isolated nucleic acid encodes a polypeptide having xylose isomerase activity, wherein said polypeptide has at least 10% higher specific xylose isomerase activity than the xylose isomerase encoded by SEQ. ID. No. 2, and wherein said isolated nucleic acid is mutated, with respect to SEQ. ID. No. 2, such that nucleotide codon 1114-1116 encodes any amino acid except glutamic acid.
Specification