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首页> 外文期刊>Marine Chemistry >Contrasting patterns of peptidase activities in seawater and sediments: An example from Arctic fjords of Svalbard
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Contrasting patterns of peptidase activities in seawater and sediments: An example from Arctic fjords of Svalbard

机译：海水和沉积物中肽酶活性的对比模式：以斯瓦尔巴群岛的北极峡湾为例

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The structural specificities and activities of microbial extracellular enzymes help determine the nature and quantity of substrates available for microbial uptake, and therefore the rate and location of organic matter transformation in the ocean. Previous work has demonstrated major differences in the spectrum of enzymes hydrolyzing polysaccha-rides in the water column and sediments, particularly in high-latitude locations. To determine whether pelagic-benthic contrasts in enzyme activities extend to other classes of organic matter, the hydrolysis of five peptide substrates was investigated in two Arctic fjords of Svalbard. Substrates were intended to measure leucine aminopep-tidase activity (exo-acting; terminal-unit cleaving), plus chymotrypsin and trypsin activities (endo-acting; mid-chain cleaving). All substrates were readily hydrolyzed in surface sediments. In contrast only two to four of the peptide substrates were hydrolyzed in the water column of both fjords. Chymotrypsin activities were undetectable or were far lower than trypsin and leucine aminopeptidase activities in the water column, but were comparable to the activities of other enzymes in sediments. The pelagic-benthic contrast in the spectrum of peptide substrates hydrolyzed in these fjords parallels patterns of hydrolysis previously observed for polysaccharides. Some organic matter may pass untouched through the water column due to a lack of the specific enzymes required for hydrolysis; these substrates could then selectively fuel benthic metabolism. Pelagic-benthic contrasts in enzymatic capabilities may be widespread in the ocean, and thus affect the processing of a significant fraction of marine organic matter.
机译：微生物细胞外酶的结构特异性和活性有助于确定可用于微生物吸收的底物的性质和数量，从而确定海洋中有机物转化的速率和位置。先前的工作已经证明了水解水柱和沉积物中（尤其是在高纬度地区）多糖的酶谱的主要差异。为了确定酶活性的上层-底栖对比是否扩展到其他类别的有机质，在斯瓦尔巴群岛的两个北极峡湾中研究了五种肽底物的水解。底物旨在测量亮氨酸氨基肽酶的活性（外显作用；末端单位裂解），以及胰凝乳蛋白酶和胰蛋白酶活性（内生作用；中链裂解）。所有底物都容易在表面沉积物中水解。相反，在两个峡湾的水柱中只有两到四个肽底物被水解。胰凝乳蛋白酶的活性无法检测到或远低于水柱中的胰蛋白酶和亮氨酸氨肽酶的活性，但与沉积物中其他酶的活性相当。在这些峡湾中水解的肽底物谱中的上层-底层对比与以前观察到的多糖的水解模式相似。由于缺乏水解所需的特定酶，一些有机物可能会原样通过水柱。这些底物然后可以选择性地促进底栖生物的代谢。酶能力的中上层-底层对比可能在海洋中广泛传播，因此影响了很大一部分海洋有机物的加工。

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