Temperature-stable glycosylated recombinant chicken cystatin and the use thereof
The present invention relates to a N-glycosylation-modified recombinant chicken cystatin, characterized in that Asn 106 -Ile 108 in its amino acid sequence is modified to Asn 106 -Thr 108 . The present invention also relates to a method for producing said N-glycosylation-modified recombinant chicken cystatin, wherein a site-directed mutated cDNA encoding chicken cystatin is cloned in an expression vector, with which a yeast strain is in turn transformed, and the yeast transformant is then cultured for producing a recombinant chicken cystatin wherein the Asn residue in the Asn 106 -Thr 108 of its amino acid sequence that is produced by said site-directed mutagenesis can be modified by N-glycosylation. The N-glycosylation-modified recombinant chicken cystatin disclosed in the present invention has improved stability in a freezing-thawing process and in a heating process.
1. An isolated N-glycosylation-modifled recombinant chicken cystatin, characterized in that Asn 106 -Ile 108 in its amino acid sequence is modified to Asn 106 -Thr 108 , and wherein the isolated N-glycosylated recombinant chicken cystatin has an improved stability in a freezing-thawing process and in a heating process.
2. The N-glycosylation-modifled recombinant chicken cystatin of claim 1 , which functions in the inhibition of thermal degradation and gel softening of surimi.
3. The N-glycosylation-modified recombinant chicken cystatin of claim 1 , wherein said surimi is derived from nemipterid, mackerel or cod.
4. A composition for inhibiting the thermal degradation of surimi, comprising the N-glycosylation-modified recombinant chicken cystatin of claim 1 and an expander selected from the group consisting of a compatible protein, starch or a combination thereof.
5. A method of using the composition of claim 4 for inhibiting the thermal degradation of surimi, comprising adding the composition of claim 4 to surimi.
6. The method of claim 5 , wherein the surimi is derived from nemipterid, mackerel or cod.
7. The method of claim 5 or 6 , wherein 0.01 to 0.10 active units, of the N-glycosylation-modified recombinant chicken cystatin of claim 1 per 1 g of surimi is added.
8. The method of claim 7 , wherein 0.02 to 0.05 active units of the N-glycosylation-modified recombinant chicken cystatin of claim 1 per 1 g of surimi is added.