Gupta R, Beg Q K, Khan S, Chauhan B
Department of Microbiology, University of Delhi South Campus, Benito Juarez Marg, New Delhi 110 021, India.
Appl Microbiol Biotechnol. 2002 Dec;60(4):381-95. doi: 10.1007/s00253-002-1142-1. Epub 2002 Oct 12.
Microbial alkaline proteases dominate the worldwide enzyme market, accounting for a two-thirds share of the detergent industry. Although protease production is an inherent property of all organisms, only those microbes that produce a substantial amount of extracellular protease have been exploited commercially. Of these, strains of Bacillus sp. dominate the industrial sector. To develop an efficient enzyme-based process for the industry, prior knowledge of various fermentation parameters, purification strategies and properties of the biocatalyst is of utmost importance. Besides these, the method of measurement of proteolytic potential, the selection of the substrate and the assay protocol depends upon the ultimate industrial application. A large array of assay protocols are available in the literature; however, with the predominance of molecular approaches for the generation of better biocatalysts, the search for newer substrates and assay protocols that can be conducted at micro/nano-scale are becoming important. Fermentation of proteases is regulated by varying the C/N ratio and can be scaled-up using fed-batch, continuous or chemostat approaches by prolonging the stationary phase of the culture. The conventional purification strategy employed, involving e.g., concentration, chromatographic steps, or aqueous two-phase systems, depends on the properties of the protease in question. Alkaline proteases useful for detergent applications are mostly active in the pH range 8-12 and at temperatures between 50 and 70 degrees C, with a few exceptions of extreme pH optima up to pH 13 and activity at temperatures up to 80-90 degrees C. Alkaline proteases mostly have their isoelectric points near to their pH optimum in the range of 8-11. Several industrially important proteases have been subjected to crystallization to extensively study their molecular homology and three-dimensional structures.
微生物碱性蛋白酶在全球酶市场中占据主导地位，在洗涤剂行业中占三分之二的份额。尽管蛋白酶的产生是所有生物体的固有特性，但只有那些能产生大量胞外蛋白酶的微生物才被用于商业开发。其中，芽孢杆菌属的菌株在工业领域占主导地位。为该行业开发一种基于酶的高效工艺，了解各种发酵参数、纯化策略和生物催化剂的特性至关重要。除此之外，蛋白水解潜力的测量方法、底物的选择和测定方案取决于最终的工业应用。文献中有大量的测定方案；然而，随着用于生成更好生物催化剂的分子方法的盛行，寻找能够在微/纳米尺度上进行的新型底物和测定方案变得越来越重要。蛋白酶的发酵通过改变碳氮比来调节，并且可以通过延长培养的稳定期，采用补料分批、连续或恒化器方法进行放大。所采用的传统纯化策略，例如涉及浓缩、色谱步骤或双水相系统，取决于所讨论的蛋白酶的特性。用于洗涤剂应用的碱性蛋白酶大多在pH值8 - 12范围内以及50至70摄氏度之间具有活性，少数例外情况是最适pH值高达13，以及在高达80 - 90摄氏度的温度下具有活性。碱性蛋白酶的等电点大多在其最适pH值附近，范围为8 - 11。几种具有工业重要性的蛋白酶已经进行了结晶，以广泛研究它们的分子同源性和三维结构。
