Bacillus a-amylase

Disulfide interchange was also found to dominate mostly in another case the difference in half-lives r1/2 at 90°C and pH 6.5 of Bacillus a-amylases extended two orders of magnitude from Bacillus amyloliquefaciens through B. slearolhermophilus to B. licheniformis (Tomazic, 1988). For B. licheniformis a-amylase, deamidation of Asn/Gln residues was the main cause of inactivation. The cause of thermostability... 

S. J. Tomazie and A. M. Klibanov, Mechanisms of irreversible thermal inactivation of bacillus a-amylases,... 

Amylases classified in family 13 glycoside hydrolases have been described from the archaea to the bacteria domains. The genus Bacillus includes a set of species able to produce starch-d rading enzymes and has biotechnological potential as a source of these enzymes especially the a-amylases, which are the most fi equent starch-degrading enzymes described for bacteria. In addition. Bacillus a-amylases present activity and are stable in temperatures over 50-60 °C, therefore are very attractive for industrial applications. B. subtilis, Bacillus stearothermophilus. Bacillus lichenifortnis, and Bacillus atnyloliquefaciens have been widely used for commercial production of amylases and for the production of starch derivates. The a-amylases produced by other bacteria and also archaea have to compete with the Bacillus enzymes that already present excellent thermophilic properties and high conversion rates (Prakash and Jaiswal 2010). 

Fig. 1. Enzymatic liquefaction processes (9). Alpha-S is the a-amylase from bacillus subtilis alpha-L/ST are a-amylases from B. licheniformis oi B.

A.mylases. Commercial laundry amylases comprise the a-amylase from bacillus amyloliquefaciens and the heat-stable a-amylase from bacillus licheniformis. 

In the alcohol industry, grain or potato raw materials are milled and water added to form a slurry or mash which is heated either batchwise or continuously. Traditionally, the mash is heated to 150°C by the injection of Uve steam. To reduce viscosity, a-amylases are added both during beating to 150°C and during cooling. Thermostable a-amylases from Bacillus licheniformis are the most commonly used enzymes for these processes (68). 

Isolation of a-amylase and protease from Bacillus subtilis fermentation broth [20]... 

Aldolase (muscle and liver)[4] Aminopeptidase[5] a-Amylase (Bacillus subtilis)[6]... 

Fischer, brilliant results were achieved, and in succession the a-amylases of pig pancreas, of Bacillus subtilis, of human saliva, of human pancreas, and of Aspergillus oryzae, and the /3-amylase of malt, were successfully crystallized. Important biological deductions were gained from this study whereas the amylases of human pancreas and saliva cannot be distinguished from one another, amylases from pig pancreas and from human pancreas are different. These differences are manifested in molecular weight, crystalline forms, electrophoretic mobility, and influence of the pH on the activity however, all the amylases have the same specific biochemical action. The identity of the enzymes seems to be dependent on the species and not on the organ. Interest in biologically active proteins led Meyer to a study of the protein hormones, a field in which he was very active at the time of his death. 

In this chapter we describe the use of pea seeds to express the bacterial enzyme a-amylase. Bacterial exoenzymes like the heat stable a-amylase from Bacillus licheni-formis are important for starch hydrolysis in the food industry. The enzymatic properties of a-amylase are well understood [13,14], it is one of the most thermostable enzymes in nature and it is the most commonly used enzyme in biotechnological processes. Although fermentation in bacteria allows highly efficient enzyme production, plant-based synthesis allows in situ enzymatic activity to degrade endogenous reserve starch, as shown in experiments with non-crop plants performed under greenhouse conditions [12,15]. Finally, the quantitative and sensitive detection of a-amylase activ-... 

Potato dry matter is ground to a powder using a mortar and pestle. To 100 mg potato dry matter, 100 p,L (300 U) of a-amylase (e.g. from Bacillus species. Sigma A-6380, St Louis,... 

Shukla, J., Kar, R. (2006). Potato peel as a solid state substrate for thermostable a-amylase production by thermophilic Bacillus isolates. World J. Microbiol. BiotechnoL, 22, 417 22. 

In 2002, Do et al. [85] proposed a pathway for the enzymatic synthesis of (-)-menthyl a-maltoside and a-maltooligosides from (-)-menthyl a-glucoside using cyclodextrin glucanotransferase obtained from Bacillus macerans. The reaction can be performed in a reactor containing (-)-menthyl a-glucoside, the enzyme and soluble starch the yield was about 80% 15% (-)-menthyl a-malto-side and 65% (-)-menthyl a-maltooligosides, respectively. Treatment of the starch with a-amylase can raise the proportion of (-)-menthyl a-maltoside. 

Several amylases have been partially sequenced (42-45). For example, a-amylase from Bacillus subtilis, which is composed of two subunits of 24,000 molecular weight each, has an amino terminal sequence as shown in Table V (42). Perhaps fortuitously, the sequence of residues 8 through 12 resembles residues 14 through 18 in xylanase A, in that a polar residue is surrounded by four aromatic residues. 

Among hydrolases with allergenic properties used in the food industry there are a-amylases, amyloglucosidases, glucoamylases, cellulases, hemicellulases, pecti-nases, lipoxygenases, and xylanases (Bindslev-Jensen et al. 2006, Cullinan et al. 1997, Houba et al. 1997, Kanerva and Vanhanen 1999, 2001, Scheibe et al. 2001). Most of these enzymes are synthesized by A. otyzae fungi or Bacillus subtilis bacteria. 

The organism that elaborates this a-amylase was originally called Bacillus subtilis. It was reclassified as Bacillus amyloliquefaciens in 1967.8... 

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