Amylase

About: Amylase is a research topic. Over the lifetime, 14164 publications have been published within this topic receiving 296069 citations.

Involvement of α-Amylase I-1 in Starch Degradation in Rice Chloroplasts

Abstract: To determine the role of alpha-amylase isoform I-1 in the degradation of starch in rice leaf chloroplasts, we generated a series of transgenic rice plants with suppressed expression or overexpression of alpha-amylase I-1. In the lines with suppressed expression of alpha-amylase I-1 at both the mRNA and protein levels, seed germination and seedling growth were markedly delayed in comparison with those in the wild-type plants. However, the growth retardation was overcome by supplementation of sugars. Interestingly, a significant increase of starch accumulation in the young leaf tissues was observed under a sugar-supplemented condition. In contrast, the starch content of leaves was reduced in the plants overexpressing alpha-amylase I-1. In immunocytochemical analysis with specific anti-alpha-amylase I-1 antiserum, immuno-gold particles deposited in the chloroplasts and extracellular space in young leaf cells. We further examined the expression and targeting of alpha-amylase I-1 fused with the green fluorescent protein in re-differentiated green cells, and showed that the fluorescence of the expressed fusion protein co-localized with the chlorophyll autofluorescence in the transgenic cells. In addition, mature protein species of alpha-amylase I-1 bearing an oligosaccharide side chain were detected in the isolated chloroplasts. Based on these results, we concluded that alpha-amylase I-1 targets the chloroplasts through the endoplasmic reticulum-Golgi system and plays a significant role in the starch degradation in rice leaves.

Very stable enzymes from extremely thermophilic archaebacteria and eubacteria

Abstract: Thirty-six thermophilic archaebacteria and nine extremely thermophilic eubacteria have been screened on solid media for extracellular amylase, protease, hemicellulase (xylanase), cellulase, pectinase and lipase activities. Extracellular enzymes were detected in 14 archaebacteria belonging to three different orders. Twelve of these were able to degrade starch and casein and the two Thermofilum strains were able to degrade starch, xylan and carboxymethylcellulose. Three of the eubacteria could degrade only starch. The other six (including four Thermotoga strains) all had activity against starch, xylan and carboxymethylcellulose, and one also had activity against casein. Some of the amylolytic archaebacteria released α-glucosidase, β-glucosidase, amylase and transglucosylase activities into liquid media containing starch or maltose. Thermotoga strain FjSS3B.1 released amylase, xylanase, cellulase and β-glucosidase activities into the medium when grown in the presence of substrates. When the partially purified enzymes from Thermotoga and some of the archaebacteria were compared with known thermostable enzymes the majority were found to be the most thermostable of their type. The β-glucosidase, xylanase and cellulase from Thermotoga and two α-glucosidases, a β-glucosidase, an amylase and a pullulanase from archaebacteria all have half-lives of at least 15 min at 105°C.

Production and partial characterization of extracellular amylase enzyme from Bacillus amyloliquefaciens P-001

Abstract: Amylases are one of the most important enzymes in present-day biotechnology. The present study was concerned with the production and partial characterization of extracellular amylase from Bacillus amyloliquefaciens P-001. The effect of various fermentation conditions on amylase production through shake-flask culture was investigated. Enzyme production was induced by a variety of starchy substrate but corn flour was found to be a suitable natural source for maximum production. Tryptone and ammonium nitrate (0.2%) as nitrogen sources gave higher yield compared to other nitrogen sources. Maximum enzyme production was obtained after 48 hrs of incubation in a fermentation medium with initial pH 9.0 at 42°C under continuous agitation at 150 rpm. The size of inoculum was also optimized which was found to be 1% (v/v). Enzyme production was 2.43 times higher after optimizing the production conditions as compared to the basal media. Studies on crude amylase revealed that optimum pH, temperature and reaction time of enzyme activity was 6.5, 60°C and 40 minutes respectively. About 73% of the activity retained after heating the crude enzyme solution at 50°C for 30 min. The enzyme was activated by Ca2+ (relative activity 146.25%). It was strongly inhibited by Mn2+, Zn2+ and Cu2+, but less affected by Mg2+ and Fe2+.

The breakdown of starch in leaves

Abstract: This review describes recent progress in discovering the pathway of starch breakdown in leaves. The synthesis of starch from photo-assimilated carbon is one of the major biochemical fluxes in plants. Despite this, the pathway through which this starch is remobilized has not been defined. Numerous enzymes that could participate in starch breakdown are present in leaves, but until recently, the relative importance of each had not been determined. Through studies using model species such as Arabidopsis and potato, significant progress has now been made in determining the roles of known enzymes, and in the discovery of novel proteins necessary for breakdown. These data allow a tentative pathway for starch breakdown to be mapped out, involving hydrolysis primarily to maltose and subsequent maltose export to the cytosol. This provides a framework for complete discovery of the pathway and for the analysis of its regulation. Contents Summary 247 I. Introduction 247 II. Structure of the starch granule 248 III. Initial attack on the granule and the role of glucan, water dikinase 249 IV. Debranching of branched glucans 250 V. The metabolism of linear glucans 251 VI. Export of starch catabolites 254 VII. Metabolism of glucose and maltose 255 VIII. The emerging pathway of starch breakdown and its regulation 256 Acknowledgements 258 References 258.

Biotechnological Processes in Microbial Amylase Production.

Abstract: Amylase is an important and indispensable enzyme that plays a pivotal role in the field of biotechnology. It is produced mainly from microbial sources and is used in many industries. Industrial sectors with top-down and bottom-up approaches are currently focusing on improving microbial amylase production levels by implementing bioengineering technologies. The further support of energy consumption studies, such as those on thermodynamics, pinch technology, and environment-friendly technologies, has hastened the large-scale production of the enzyme. Herein, the importance of microbial (bacteria and fungi) amylase is discussed along with its production methods from the laboratory to industrial scales.