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A porous-cross linked enzyme aggregates of maltogenic amylase from Bacillus lehensis G1: Robust biocatalyst with improved stability and substrate diffusion

Nawawi NN, Hashim Z, Manas NHA, Azelee NIW, Illias RM

Int J Biol Macromol, 2020 Apr 01;148:1222-1231.
PMID: 31759025 DOI: 10.1016/j.ijbiomac.2019.10.101

Enzymatic synthesis of maltooligosaccharides is hampered due to lack of stability of soluble enzyme. This limitation can be tackled by cross linked enzyme aggregates (CLEAs) immobilization approach. However, substrate diffusion is a major bottleneck in cross linking technology. Herein, CLEAs of maltogenic amylase from Bacillus lehensis G1 (Mag1) was developed with addition of porous agent (Mag1-p-CLEAs). Comparison of thermal, pH and kinetic analysis with CLEAs without porous agent (Mag1-CLEAs) and free Mag1 was performed. Mag1-p-CLEAs with porous structure prepared at 0.8% (w/v) of citrus pectin (porous agent), 0.25% (w/v) of chitosan (cross linker) and cross linked for 1.5 h yielded 91.20% activity. 80% of activity is retained after 30 min of incubation at 40 °C and showed longer half-life than free Mag1 and Mag1-CLEAs. Mag1-p-CLEAs also showed pH stability at acidic and alkaline pH. The 1.68-fold increase in Vmax value in comparison to Mag1-CLEAs showed that the presence of pores of Mag1-p-CLEAs enhanced the beta-cyclodextrin accessibility. The increase in high catalytic efficiency (Kcat/Km) value, 1.90-fold and 1.05-fold showed that it also has better catalytic efficiency than free Mag1 and Mag1-CLEAs, respectively. Mag1-p-CLEAs not only improved substrate diffusibility of CLEAs, but also leads to higher thermal and pH stability of Mag1.

Matched MeSH terms: Protein Aggregates*
Probing the anti-Aβ42 aggregation and protective effects of prenylated xanthone against Aβ42-induced toxicity in transgenic Caenorhabditis elegans model

Thew HY, Boon Keat K, Tan YC, Ong YS, Parat MO, Murugaiyah V, et al.

Chem Biol Interact, 2024 May 01;394:110978.
PMID: 38552766 DOI: 10.1016/j.cbi.2024.110978

Alzheimer's disease (AD) is a progressive neurodegenerative disorder characterized by the accumulation of amyloid-β (Aβ) protein aggregates, leading to synaptic dysfunction and neuronal cell death. In this study, we used a comprehensive approach encompassing in vitro assays, computational analyses, and an in vivo Caenorhabditis elegans model to evaluate the inhibitory effects of various xanthones, focusing on Garcinone D (GD), on Aβ42 oligomer formation. Dot blot analysis revealed concentration-dependent responses among xanthones, with GD consistently inhibiting Aβ42 oligomer formation at low concentrations (0.1 and 0.5 μM, inhibitions of 84.66 ± 2.25% and 85.06 ± 6.57%, respectively). Molecular docking and dynamics simulations provided insights into the molecular interactions between xanthones and Aβ42, highlighting the disruption of key residues involved in Aβ42 aggregation. The neuroprotective potential of GD was established using transgenic C. elegans GMC101, with substantial delays in paralysis reported at higher concentrations. Our findings show that GD is a potent suppressor of Aβ42 oligomer formation, suggesting its potential as a therapeutic candidate for AD. The concentration-dependent effects observed in both in vitro and in vivo models underscore the need for nuanced dose-response assessments. These findings contribute novel insights into the therapeutic landscape of xanthones against AD, emphasizing the multifaceted potential of GD for further translational endeavors in neurodegenerative disorder research.

Matched MeSH terms: Protein Aggregates/drug effects
Fulltext Assessing SABU (Serum Anti Bisa Ular), the sole Indonesian antivenom: A proteomic analysis and neutralization efficacy study

Tan CH, Liew JL, Tan KY, Tan NH

Sci Rep, 2016 11 21;6:37299.
PMID: 27869134 DOI: 10.1038/srep37299

Serum Anti Ular Bisa (SABU) is the only snake antivenom produced locally in Indonesia; however, its effectiveness has not been rigorously evaluated. This study aimed to assess the protein composition and neutralization efficacy of SABU. SDS polyacrylamide gel electrophoresis, size-exclusion liquid chromatography and shotgun proteomics revealed that SABU consists of F(ab')2 but a significant amount of dimers, protein aggregates and contaminant albumins. SABU moderately neutralized Calloselasma rhodostoma venom (potency of 12.7 mg venom neutralized per ml antivenom, or 121.8 mg venom per g antivenom protein) and Bungarus fasciatus venom (0.9 mg/ml; 8.5 mg/g) but it was weak against the venoms of Naja sputatrix (0.3 mg/ml; 2.9 mg/g), Naja sumatrana (0.2 mg/ml; 1.8 mg/g) and Bungarus candidus (0.1 mg/ml; 1.0 mg/g). In comparison, NPAV, the Thai Neuro Polyvalent Antivenom, outperformed SABU with greater potencies against the venoms of N. sputatrix (0.6 mg/ml; 8.3 mg/g), N. sumatrana (0.5 mg/ml; 7.1 mg/g) and B. candidus (1.7 mg/ml; 23.2 mg/g). The inferior efficacy of SABU implies that a large antivenom dose is required clinically for effective treatment. Besides, the antivenom contains numerous impurities e.g., albumins that greatly increase the risk of hypersensitivity. Together, the findings indicate that the production of SABU warrants further improvement.

Matched MeSH terms: Protein Aggregates
Multitarget drug design strategy in Alzheimer's disease: focus on cholinergic transmission and amyloid-β aggregation

Simoni E, Bartolini M, Abu IF, Blockley A, Gotti C, Bottegoni G, et al.

Future Med Chem, 2017 06;9(10):953-963.
PMID: 28632446 DOI: 10.4155/fmc-2017-0039

AIM: Alzheimer pathogenesis has been associated with a network of processes working simultaneously and synergistically. Over time, much interest has been focused on cholinergic transmission and its mutual interconnections with other active players of the disease. Besides the cholinesterase mainstay, the multifaceted interplay between nicotinic receptors and amyloid is actually considered to have a central role in neuroprotection. Thus, the multitarget drug-design strategy has emerged as a chance to face the disease network.
METHODS: By exploiting the multitarget approach, hybrid compounds have been synthesized and studied in vitro and in silico toward selected targets of the cholinergic and amyloidogenic pathways.
RESULTS: The new molecules were able to target the cholinergic system, by joining direct nicotinic receptor stimulation to acetylcholinesterase inhibition, and to inhibit amyloid-β aggregation.
CONCLUSION: The compounds emerged as a suitable starting point for a further optimization process.

Matched MeSH terms: Protein Aggregates/drug effects
Synthetic Curcumin Analogs as Inhibitors of β -Amyloid Peptide Aggregation: Potential Therapeutic and Diagnostic Agents for Alzheimer's Disease

Bukhari SN, Jantan I

Mini Rev Med Chem, 2015;15(13):1110-21.
PMID: 26420724

There is a crucial need to develop new effective drugs for Alzheimer's disease (AD) as the currently available AD treatments provide only momentary and incomplete symptomatic relief. Amongst natural products, curcumin, a major constituent of turmeric, has been intensively investigated for its neuroprotective effect against β-amyloid (Aβ)-induced toxicity in cultured neuronal cells. The ability of curcumin to attach to Aβ peptide and prevent its accumulation is attributed to its three structural characteristics such as the presence of two aromatic end groups and their co-planarity, the length and rigidity of the linker region and the substitution conformation of these aromatics. However, curcumin failed to reach adequate brain levels after oral absorption in AD clinical trials due to its low water solubility and poor oral bioavailability. A number of new curcumin analogs that mimic the active site of the compound along with analogs that mimic the curcumin anti-amyloid effect combined with anticholinesterase effect have been developed to enhance the bioavailability, pharmacokinetics, water solubility, stability at physiological conditions and delivery of curcumin. In this article, we have summarized all reported synthetic analogs of curcumin showing effects on β-amyloid and discussed their potential as therapeutic and diagnostic agents for AD.

Matched MeSH terms: Protein Aggregates/drug effects
Biological evaluation of synthetic α,β-unsaturated carbonyl based cyclohexanone derivatives as neuroprotective novel inhibitors of acetylcholinesterase, butyrylcholinesterase and amyloid-β aggregation

Zha GF, Zhang CP, Qin HL, Jantan I, Sher M, Amjad MW, et al.

Bioorg Med Chem, 2016 05 15;24(10):2352-9.
PMID: 27083471 DOI: 10.1016/j.bmc.2016.04.015

A series of new α,β-unsaturated carbonyl-based cyclohexanone derivatives was synthesized by simple condensation method and all compounds were characterized by using various spectroscopic techniques. New compounds were evaluated for their effects on acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE). These compounds were also screened for in vitro cytotoxicity and for inhibitory activity for self-induced Aβ1-42 aggregation. The effect of these compounds against amyloid β-induced cytotoxicity was also investigated. The findings of in vitro experiment revealed that most of these compounds exhibited potent inhibitory activity against AChE and self-induced Aβ1-42 aggregation. The compound 3o exhibited best AChE (IC50=0.037μM) inhibitory potential. Furthermore, compound 3o disassembled the Aβ fibrils produced by self-induced Aβ aggregation by 76.6%. Compounds containing N-methyl-4-piperidone linker, showed high acetylcholinesterase and self-induced Aβ aggregation inhibitory activities as compared to reference drug donepezil. The pre-treatment of cells with synthetic compounds protected them against Aβ-induced cell death by up to 92%. Collectively, these findings suggest that some compounds from this series have potential to be promising multifunctional agents for AD treatment and our study suggest the cyclohexanone derivatives as promising new inhibitors for AChE and BuChE, potentially useful to treat neurodegenerative diseases.

Matched MeSH terms: Protein Aggregates/drug effects
Fulltext Loss of mRNA surveillance pathways results in widespread protein aggregation

Jamar NH, Kritsiligkou P, Grant CM

Sci Rep, 2018 03 01;8(1):3894.
PMID: 29497115 DOI: 10.1038/s41598-018-22183-2

Eukaryotic cells contain translation-associated mRNA surveillance pathways which prevent the production of potentially toxic proteins from aberrant mRNA translation events. We found that loss of mRNA surveillance pathways in mutants deficient in nonsense-mediated decay (NMD), no-go decay (NGD) and nonstop decay (NSD) results in increased protein aggregation. We have isolated and identified the proteins that aggregate and our bioinformatic analyses indicates that increased aggregation of aggregation-prone proteins is a general occurrence in mRNA surveillance mutants, rather than being attributable to specific pathways. The proteins that aggregate in mRNA surveillance mutants tend to be more highly expressed, more abundant and more stable proteins compared with the wider proteome. There is also a strong correlation with the proteins that aggregate in response to nascent protein misfolding and an enrichment for proteins that are substrates of ribosome-associated Hsp70 chaperones, consistent with susceptibility for aggregation primarily occurring during translation/folding. We also identified a significant overlap between the aggregated proteins in mRNA surveillance mutants and ageing yeast cells suggesting that translation-dependent protein aggregation may be a feature of the loss of proteostasis that occurs in aged cell populations.

Matched MeSH terms: Protein Aggregates/physiology*
Natural Products Combating Neurodegeneration: Parkinson's Disease

Solayman M, Islam MA, Alam F, Khalil MI, Kamal MA, Gan SH

Curr Drug Metab, 2017;18(1):50-61.
PMID: 27396919 DOI: 10.2174/1389200217666160709204826

Parkinson's disease (PD) is characterized by neurodegeneration and a progressive functional impairment of the midbrain nigral dopaminergic neurons. The cause remains unknown; however, several pathological processes and central factors, such as protein aggregation, mitochondrial dysfunction, iron accumulation, neuroinflammation and oxidative stress, have been reported. The current treatment method primarily targets symptoms by using anti-Parkinson drugs such as levodopa, carbidopa, dopamine (DA) agonists, monoamine oxidase type B inhibitors and anticholinergics to replace DA. When drug therapy is not satisfactory, surgical treatments are recommended. Unfortunately, the existing conventional strategies that target PD are associated with numerous side effects and possess an economic burden. Therefore, novel therapeutic approaches that regulate the pathways leading to neuronal death and dysfunction are necessary. For many years, nature has provided the primary resource for the discovery of potential therapeutic agents. Remarkably, many natural products from medicinal plants, fruits and vegetables have been demonstrated to be efficacious anti-Parkinson agents. These products possess neuroprotective properties as a result of not only their wellrecognized anti-oxidative and anti-inflammatory activities but also their inhibitory roles regarding iron accumulation, protein misfolding and the maintenance of proteasomal degradation, as well as mitochondrial homeostasis. The aim of this review is to report the available anti-Parkinson agents based on natural products and delineate their therapeutic actions, which act on various pathways. Overall, this review emphasizes the types of natural products that are potential future resources in the treatment of PD as novel regimens or supplementary agents.

Matched MeSH terms: Protein Aggregates
Entrapment of porous cross-linked enzyme aggregates of maltogenic amylase from Bacillus lehensis G1 into calcium alginate for maltooligosaccharides synthesis

Nawawi NN, Hashim Z, Rahman RA, Murad AMA, Bakar FDA, Illias RM

Int J Biol Macromol, 2020 May 01;150:80-89.
PMID: 32035147 DOI: 10.1016/j.ijbiomac.2020.02.032

Maltooligosaccharides (MOSs) are emerging oligosaccharides in food-based applications and can be synthesized through the enzymatic synthesis of maltogenic amylase from Bacillus lehensis G1 (Mag1). However, the lack of enzyme stability makes this approach unrealistic for industrial applications. The formation of cross-linked enzyme aggregates (CLEAs) is a promising tool for improving enzyme stability, and the substrate accessibility problem of CLEA formation was overcome by the addition of porous agents to generate porous CLEAs (p-CLEAs). However, p-CLEAs exhibited high enzyme leaching and low solvent tolerance. To address these problems, p-CLEAs of Mag1 (Mag1-p-CLEAs) were entrapped in calcium alginate beads (CA). Mag1-p-CLEAs-CA prepared with 2.5% (w/v) sodium alginate and 0.6% (w/v) calcium chloride yielded 53.16% (17.0 U/mg) activity and showed a lower deactivation rate and longer half-life than those of entrapped free Mag1 (Mag1-CA) and entrapped non-porous Mag1-CLEAs (Mag1-CLEAs-CA). Moreover, Mag1-p-CLEAs-CA exhibited low enzyme leaching and high tolerance in various solvents compared to Mag1-p-CLEAs. A kinetic study revealed that Mag1-p-CLEAs-CA exhibited relatively high affinity towards beta-cyclodextrin (β-CD) (Km = 0.62 mM). MOSs (300 mg/g) were synthesized by Mag1-p-CLEAs-CA at 50 °C. Finally, the reusability of Mag1-p-CLEAs-CA makes them as a potential biocatalyst for the continuous synthesis of MOSs.

Matched MeSH terms: Protein Aggregates
Fulltext Recent updates in the treatment of neurodegenerative disorders using natural compounds

Rasool M, Malik A, Qureshi MS, Manan A, Pushparaj PN, Asif M, et al.

Evid Based Complement Alternat Med, 2014;2014:979730.
PMID: 24864161 DOI: 10.1155/2014/979730

Neurodegenerative diseases are characterized by protein aggregates and inflammation as well as oxidative stress in the central nervous system (CNS). Multiple biological processes are linked to neurodegenerative diseases such as depletion or insufficient synthesis of neurotransmitters, oxidative stress, abnormal ubiquitination. Furthermore, damaging of blood brain barrier (BBB) in the CNS also leads to various CNS-related diseases. Even though synthetic drugs are used for the management of Alzheimer's disease, Parkinson's disease, autism, and many other chronic illnesses, they are not without side effects. The attentions of researchers have been inclined towards the phytochemicals, many of which have minimal side effects. Phytochemicals are promising therapeutic agents because many phytochemicals have anti-inflammatory, antioxidative as well as anticholinesterase activities. Various drugs of either synthetic or natural origin applied in the treatment of brain disorders need to cross the BBB before they can be used. This paper covers various researches related to phytochemicals used in the management of neurodegenerative disorders.

Matched MeSH terms: Protein Aggregates
Effects of formulation development methods on the stability of model protein pharmaceuticals embedded in solid lipid matrices

Tabbassum M, Zeeshan F

Pharm Dev Technol, 2019 Jun;24(5):649-662.
PMID: 30474456 DOI: 10.1080/10837450.2018.1551902

This study was conducted to investigate the influence of formulation development methods on the stability (secondary structure, aggregation, and biological activity) of protein drugs embedded in lipid matrices. Catalase, horseradish peroxidase, and α-chymotrypsin were employed as model proteins, while Precirol® AT05 (glyceryl palmitostearate) was used as lipid matrix. Protein-loaded lipid matrices were prepared using melting and mixing and wet granulation methods. Attenuated total reflectance Fourier transform infrared (ATR FT-IR) spectroscopy, size exclusion chromatography (SEC) and biological activity analyses were performed. ATR FT-IR analysis indicated significant interference of the lipid with the protein amide-I band, which was eliminated using spectral subtraction. Wet granulation method induced more changes in protein secondary structure compared to melting and mixing method. SEC analysis gave evidence of protein aggregation for catalase upon adopting the wet granulation method. The biological activity of catalase was found to reduce significantly than other two proteins upon using wet granulation method, which might be ascribed to both secondary structure alterations and the formation of aggregates. Horseradish peroxidase and α-chymotrypsin did not form any soluble aggregates. In conclusion, melting and mixing method emerged as a better incorporation method compared to wet granulation because of better stability shown by the formulated proteins.

Matched MeSH terms: Protein Aggregates

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