Bacillus sp. GL1 ニ オケル キサンタン ブンカイケイ ノ コウソガクテキ イデンガクテキ カイセキ オヨビ キサンタン リアーゼ ノ Xセン ケッショウ コウゾウ ニ カンスル ケンキュウ

京都大学0048新制・論文博士博士(農学)乙第11064号論農博第2446号新制||農||856(附属図書館)学位論文||H14||N3733(農学部図書室)UT51-2003-B426(主査)教授 村田 幸作, 教授 熊谷 英彦, 教授 井上 國世学位規則第4条第2項該当Doctor of Agricultural ScienceKyoto UniversityDA

Molecular Identification of Family 38 α-Mannosidase of Bacillus sp. Strain GL1, Responsible for Complete Depolymerization of Xanthan

When cells of Bacillus sp. strain GL1 were grown in a medium containing xanthan as a carbon source, α-mannosidase exhibiting activity toward p-nitrophenyl-α-d-mannopyranoside (pNP-α-d-Man) was produced intracellularly. The 350-kDa α-mannosidase purified from a cell extract of the bacterium was a trimer comprising three identical subunits, each with a molecular mass of 110 kDa. The enzyme hydrolyzed pNP-α-d-Man (K(m) = 0.49 mM) and d-mannosyl-(α-1,3)-d-glucose most efficiently at pH 7.5 to 9.0, indicating that the enzyme catalyzes the last step of the xanthan depolymerization pathway of Bacillus sp. strain GL1. The gene for α-mannosidase cloned most by using N-terminal amino acid sequence information contained an open reading frame (3,144 bp) capable of coding for a polypeptide with a molecular weight of 119,239. The deduced amino acid sequence showed homology with the amino acid sequences of α-mannosidases belonging to glycoside hydrolase family 38