Chessa J P, Feller G, Gerday C
Laboratory of Biochemistry, University of Liège, Liege-Sart Tilman, Belgium.
Can J Microbiol. 1999 Jun;45(6):452-7.
A total of 59 bacteria samples from Antarctic sea water were collected and screened for their ability to produce alpha-amylase. The highest activity was recorded from an isolate identified as an Alteromonas species. The purified alpha-amylase shows a molecular mass of about 50,000 Da and a pI of 5.2. The enzyme is stable from pH 7.5 to 9 and has a maximal activity at pH 7.5. Compared with other alpha-amylases from mesophiles and thermophiles, the "cold enzyme" displays a higher activity at low temperature and a lower stability at high temperature. The psychrophilic alpha-amylase requires both Cl- and Ca2+ for its amylolytic activity. Br- is also quite efficient as an allosteric effector. The comparison of the amino acid composition with those of other alpha-amylases from various organisms shows that the cold alpha-amylase has the lowest content in Arg and Pro residues. This could be involved in the principle used by the psychrophilic enzyme to adapt its molecular structure to the low temperature of the environment.
共收集了59份南极海水细菌样本，并对其产生α-淀粉酶的能力进行筛选。在一株被鉴定为交替单胞菌属的菌株中记录到了最高活性。纯化后的α-淀粉酶分子量约为50,000 Da，等电点为5.2。该酶在pH 7.5至9范围内稳定，在pH 7.5时具有最大活性。与来自嗜温菌和嗜热菌的其他α-淀粉酶相比，这种“冷酶”在低温下具有更高的活性，在高温下稳定性较低。嗜冷α-淀粉酶的淀粉分解活性需要Cl-和Ca2+。Br-作为变构效应剂也相当有效。将该氨基酸组成与来自各种生物体的其他α-淀粉酶的氨基酸组成进行比较表明，冷α-淀粉酶中Arg和Pro残基的含量最低。这可能与嗜冷酶使其分子结构适应低温环境所采用的原理有关。
