Isolation and Extraction of Elastase Producing Bacteria from Natural Habitat (Water-Soil Sample) and targeting it to APP, A Cause of Alzheimer’s disease

Author Name(s): *Anurag Vijay, Surendra Babu, Jyothsna Gudlapally
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Alzheimer’s disease (AD) is the most common form of dementia. There is no known cure for the disease, in fact it worsens as it progresses, and eventually leads to death. In this work the main focus was tro extract the protein elastase and intern use it to target the APP protein, a cause of Alzheimer’s. The media used in the work comprised of gelatin as a sole nutrient source. Soil contaminated water is used as the source for the isolation of the organism producing the required enzyme. From the analysis it was found that Lactobacillus fermentii was the only bacteria that showed positive test for elastase. The protein was extracted from the bacteria and was analyzed using insilico tools and softwares. There are certain reports showing that elastase is used in treating the Alzheimer’s disease. Thus the insilico analysis was carried out to detect the docking interactions of the elastase protein with the APP protein, a cause for the disease. The results were amazing, showing a great effinity of elastase to bind with APP. This shows that that elastase can be used as a drug molecule in the treatment of AD.


Elastase is a serine protease that also hydrolyzes proteins. Elastase is an enzyme found especially in pancreatic juice that catalyzes the hydrolysis of elastin. It is the main digester of elastin, which is the protein that makes up the elasticity in tissues. Elastin helps keep skin flexible but tight and stretches to accommodate normal activities like flexing a muscle. Elastase helps to digest and break down this protein, which is a component of meat. The structure of elastase is quite similar to some other serine proteases. Elastase has an active site with three main amino acids: aspartate, histidine, and serine, which make up the catalytic triad that work together to create a nucleophilic catalysis.
Elastase breaks down the Outer membrane protein A (OmpA) of E. coli and other Gram negative bacteria. Elastase also has the important immunological role of breaking down Shigella virulence factors. This is accomplished through the cleavage of peptide bonds in the target proteins. The specific peptide bonds cleaved are those on the carboxy side of small, hydrophobic amino acids such as glycine, alanine, and valine.
During the reaction in which elastase breaks down the substrate (elastin), two phases occur: a burst phase during which the amino side of the peptide bond is released, and a steady-state phase, in which the acyl side of the substrate is released. The elastin is positioned on the enzyme elastase so that the catalytic triad has access to the peptide bond. After this occurs, serine nucleophilically attacks the carbonyl of the peptide bond. A tetrahedral intermediate is formed and decomposed. Water enters the active site and attacks the reaction, causing the nitrogen terminus to leave. Water then attacks the acyl-enzyme intermediate and causes the release of the carboxylic acid component.
AD, also known in medical literature as Alzheimer disease, is the most common form of dementia. There is no cure for the disease, which worsens as it progresses, and eventually leads to death. The amyloid hypothesis postulated that extracellular beta-amyloid (Aβ) deposits are the fundamental cause of the disease. Support for this postulate comes from the location of the gene for the amyloid precursor protein (APP) on chromosome 21, together with the fact that people with trisomy 21 (Down Syndrome) who have an extra gene copy almost universally exhibit AD by 40 years of age. Also, a specific isoform of apolipoprotein, APOE4, is a major genetic risk factor for AD. Whilst apolipoproteins enhance the breakdown of beta amyloid, some isoforms are not very effective at this task (such as APOE4), leading to excess amyloid buildup in the brain. Further evidence comes from the finding that transgenic mice that express a mutant form of the human APP gene develop fibrillar amyloid plaques and Alzheimer’s-like brain pathology with spatial learning deficits.


The above research enabled the successful production & extraction of the protein elastase from bacteria and the assay of the optimal conditions for the maximum enzyme activity. The enzyme exhibited its maximum activity at pH8 and temperature 800C. In Alzheimer’s disease there is an extensive accumulation of elastin fibres in the brain which ledas to the formation of plaques. Thus the current work aims to use the elastase enzyme in the treatment of some symptoms for Alzheimer’s disease; the work also included the use of this elastase as the potent ligand to dock the APP protein, a major protein involved in Alzheimer’s disease. From the docking analysis it can be inferred that the energy of docking between the selected protein and receptor was -525, which is a confirmation for good binding affinity between the selected pair. The work can be extended further for the clinical studies to prove the efficacy of the elastase against the receptor Elastase.

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