This invention provides a polypeptide having broad substrate specificity and ω3 fatty acid-desaturating activity leading to efficiently produce a desaturation bond at ω3 position, and a polynucleotide for coding the polypeptide. Expressing the polynucleotide in vivo makes mass production of n-3 series PUFAs possible. The polypeptide comprising an amino acid sequence as shown in Sequence No. 1, which is a polypeptide having ω3 fatty acid-desaturating activity, and the polynucleotide comprising a base sequence as shown in sequence Nos.2 or 3, which is a polynucleotide for coding the polypeptide having ω3 fatty acid desaturating activity are useful for production of n-3 seriesfatty acid.本發明係提供一種具有廣泛基質專一性(specificity)、且有效率地於ω3位生成不飽和鍵之具有ω3脂肪酸不飽和化活性的多肽及編碼該多肽之聚核苷酸。藉由於生物體內使該聚核苷酸表現,而可大量生產n-3系PUFAs。屬於具有ω3脂肪酸不飽和化活性之多肽而由序列編號:1所示之胺基酸序列所構成的多肽、以及屬於編碼具有ω3脂肪酸不飽和化活性之多肽的聚核苷酸而由序列編號:2或3所示之鹼基序列所構成的聚核苷酸等可用於n-3系脂肪酸之生產。
