Identification of archaeon-producing hyperthermophilic alpha-amylase and characterization of the alpha-amylase


Autoria(s): Wang, Shujun; Lu, Zhaoxin; Lu, Mingsheng; Qin, Song; Liu, Hongfei; Deng, Xiangyuan; Lin, Qian; Chen, Jianan
Data(s)

01/09/2008

Resumo

The extremely thermophilic anaerobic archaeon strain, HJ21, was isolated from a deep-sea hydrothermal vent, could produce hyperthermophilic alpha-amylase, and later was identified as Thermococcus from morphological, biochemical, and physiological characteristics and the 16S ribosomal RNA gene sequence. The extracellular thermostable alpha-amylase produced by strain HJ21 exhibited maximal activity at pH 5.0. The enzyme was stable in a broad pH range from pH 5.0 to 9.0. The optimal temperature of alpha-amylase was observed at 95 degrees C. The half-life of the enzyme was 5 h at 90 degrees C. Over 40% and 30% of the enzyme activity remained after incubation at 100 degrees C for 2 and 3 h, respectively. The enzyme did not require Ca2+ for thermostability. This alpha-amylase gene was cloned, and its nucleotide sequence displayed an open reading frame of 1,374 bp, which encodes a protein of 457 amino acids. Analysis of the deduced amino acid sequence revealed that four homologous regions common in amylases were conserved in the HJ21 alpha-amylase. The molecular weight of the mature enzyme was calculated to be 51.4 kDa, which correlated well with the size of the purified enzyme as shown by the sodium dodecyl sulfate-polyacrylamide gel electrophoresis.

The extremely thermophilic anaerobic archaeon strain, HJ21, was isolated from a deep-sea hydrothermal vent, could produce hyperthermophilic alpha-amylase, and later was identified as Thermococcus from morphological, biochemical, and physiological characteristics and the 16S ribosomal RNA gene sequence. The extracellular thermostable alpha-amylase produced by strain HJ21 exhibited maximal activity at pH 5.0. The enzyme was stable in a broad pH range from pH 5.0 to 9.0. The optimal temperature of alpha-amylase was observed at 95 degrees C. The half-life of the enzyme was 5 h at 90 degrees C. Over 40% and 30% of the enzyme activity remained after incubation at 100 degrees C for 2 and 3 h, respectively. The enzyme did not require Ca(2+) for thermostability. This alpha-amylase gene was cloned, and its nucleotide sequence displayed an open reading frame of 1,374 bp, which encodes a protein of 457 amino acids. Analysis of the deduced amino acid sequence revealed that four homologous regions common in amylases were conserved in the HJ21 alpha-amylase. The molecular weight of the mature enzyme was calculated to be 51.4 kDa, which correlated well with the size of the purified enzyme as shown by the sodium dodecyl sulfate-polyacrylamide gel electrophoresis.

Identificador

http://ir.qdio.ac.cn/handle/337002/5665

http://www.irgrid.ac.cn/handle/1471x/166434

Idioma(s)

英语

Fonte

Wang, Shujun; Lu, Zhaoxin; Lu, Mingsheng; Qin, Song; Liu, Hongfei; Deng, Xiangyuan; Lin, Qian; Chen, Jianan.Identification of archaeon-producing hyperthermophilic alpha-amylase and characterization of the alpha-amylase,APPLIED MICROBIOLOGY AND BIOTECHNOLOGY,2008,80(4):605-614

Palavras-Chave #Biotechnology & Applied Microbiology #hyperthermophilic alpha-amylase #Thermococcus sp. #thermostability #archaeon #identification #characterization
Tipo

期刊论文