Sakka K, Kojima Y, Kondo T, Karita S, Shimada K, Ohmiya K
Department of Bioscience, Faculty of Bioresources, Mie University, Tsu, Japan.
Biosci Biotechnol Biochem. 1994 Aug;58(8):1496-9. doi: 10.1271/bbb.58.1496.
Xylanase A encoded by the Clostridium stercorarium F-9 xynA gene was purified to homogeneity from a recombinant clone of Escherichia coli. The N-terminal amino acid sequence and molecular weight (54,000) estimated by SDS-PAGE of the purified enzyme were consistent with those deduced from the nucleotide sequence [Biosci. Biotech. Biochem., 57, 273-277 (1993)]. A xylanase was also purified to homogeneity from a culture supernatant of C. stercorarium F-9. Its N-terminal amino acid sequence, molecular weight, and enzymatic properties were quite in agreement with those of the recombinant enzyme, indicating that the xynA gene was predominantly expressed as a xylanase gene in C. stercorarium F-9. The purified enzyme hydrolyzed xylotriose to yield xylobiose and xylose while it was less active toward xylobiose. It was optimally active at 75 degrees C and pH 7.0 Km and Vmax were estimated to be 1.9 mg/ml and 2.8 mumol of xylose equivalent/min/micrograms for oat spelt xylan, respectively.
由嗜热栖热梭菌F-9的xynA基因编码的木聚糖酶A从大肠杆菌的重组克隆中纯化至同质。纯化酶的N端氨基酸序列和通过SDS-PAGE估计的分子量（54,000）与从核苷酸序列推导的结果一致[生物科学、生物技术、生物化学，57，273 - 277（1993）]。还从嗜热栖热梭菌F-9的培养上清液中纯化出一种木聚糖酶至同质。其N端氨基酸序列、分子量和酶学性质与重组酶非常一致，表明xynA基因在嗜热栖热梭菌F-9中主要作为木聚糖酶基因表达。纯化的酶水解木三糖生成木二糖和木糖，而对木二糖的活性较低。它在75℃和pH 7.0时活性最佳，对于燕麦 spelts木聚糖，Km和Vmax分别估计为1.9 mg/ml和2.8 μmol木糖当量/分钟/微克。
