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Extremophiles (2014) 18:937944 DOI 10.1007/s00792-014-0674-5
REVIEW
Thermal adaptation of a-amylases: a review
Kalpana Hiteshi Reena Gupta
Received: 11 February 2014 / Accepted: 6 July 2014 / Published online: 13 August 2014 Springer Japan 2014
Abstract The temperature adaptation of a-amylase can be gained by different adjustments in protein structure with consecutive effects on the stability and exibility of the protein. In this review, meso, thermo and cold-active aamylases have been compared with respect to their structure and intramolecular interactions. With decrease in temperature, the number of ionic interactions also decreases, leading to greater exibility of proteins. It has also been observed that the proline and arginine content is higher in thermophilic amylases as compared to meso and psychrophilic amylases, increasing the rigidity and structural stability of protein molecule.
Keywords Amylase Adaptation Intramolecular
interactions Stability
Introduction
Amylases are enzymes that hydrolyze the starch molecules into polymers composed of glucose units (Windish and Mhatre 1965; Reddy et al. 2003). These are among the most important enzymes and are of great signicance in present day biotechnology (Pandey et al. 2000; Deb et al. 2013). These can be produced from several sources such as plants, animals and microbes (Vidyalakshmi et al. 2009). However, enzymes from fungal and bacterial sources (Table 1) have dominated applications in industrial sectors (de Souza and
Magalhaes 2010). The major advantage of using microorganisms for the production of amylase is the economical bulk production capacity, stability and the fact that microbes are easy to manipulate to obtain enzymes of desired characteristics (Gupta et al. 2003; Alariya et al. 2013).
Classication of amylases
Amylases can be classied in three categories on the basis of their mode of action (Table 2).
a-Amylase
a-Amylases, also known as a-1, 4-glucan-4-glucanoydrolase are the enzymes hydrolyzing a-1,4 glucosidic linkage of starch and are widely distributed in animals, plants as well as microbes (Leloup et al. 1994; Muralikrishna and Nirmala 2005; de Souza and e Magalhaes 2010). Bacillus spp. are considered to be the most important sources of aamylase and has been used for its production (Babu and Satyanarayan 1995).
b-Amylase
b-Amylases are also known as a-1, 4-glucan maltohydrolase (Daba et al. 2013). These are exo-acting enzymes. These remove b-anomeric maltose from the non-reducing end of the polysaccharides (Thoma et al. 1971)....