Naveed Ahmad Fazili

Defective Protein Folding and Aggregation as the Basis of Neurodegenerative Diseases: The Darker Aspect of Proteins

The ability of a polypeptide to fold into a unique, functional, and three-dimensional structure depends on the intrinsic properties of the amino acid sequence, function of the molecular chaperones, proteins, and enzymes. Every polypeptide has a finite tendency to misfold and this forms the darker side of the protein world. Partially folded and misfolded proteins that escape the cellular quality control mechanism have the high tendency to form inter-molecular hydrogen bonding between the same protein molecules resulting in aggregation. This review summarizes the underlying and universal mechanism of protein folding. It also deals with the factors responsible for protein misfolding and aggregation. This article describes some of the consequences of such behavior particularly in the context of neurodegenerative conformational diseases such as Alzheimer’s, Parkinson’s, Huntington’s, amyotrophic lateral sclerosis and other non-neurodegenerative conformational diseases such as cancer and cystic fibrosis etc. This will encourage a more proactive approach to the early diagnosis of conformational diseases and nutritional counseling for patients.Graphical Abstract

Induction of amyloidogenicity in wild type HEWL by a dialdehyde: Analysis involving multi dimensional approach

Physiological conditions corresponding to oxidative stress deplete the level of enzyme glyoxalase, facilitating a hike in the serum concentration of glyoxal. Simulating an elevated in vivo level of glyoxal, we tested (50%, v/v) concentration of glyoxal to interact with HEWL. Initially, docking study revealed that glyoxal binds in the hydrophobic core of the enzyme. The interaction between the dialdehyde (glyoxal) and the enzyme (HEWL) followed a three step transition involving pre-molten and molten globule states formed on days 7 and 15 of incubation respectively, which were characterised by an increase in the ANS fluorescence intensity compared to the native state. These molten globule states upon further incubation on day 20 resulted in the formation of aggregates which were characterised by an increase in ThT fluorescence intensity, red shift in Congo red absorbance, negative ellipticity peak at 217 nm in the far-UV CD and the loss of signals at 284, 290 and 294 nm in the near-UV CD spectra. Finally, TEM confirmed the authenticity of lysozyme fibril formation by displaying rod like fibrillar structure.

Anti-fibrillation potency of caffeic acid against an antidepressant induced fibrillogenesis of human α-synuclein: Implications for Parkinson's disease.

Alpha synuclein is a 14 kDa intrinsically disordered, presynaptic protein whose fibrillation is a critical step in the pathogenesis of Parkinsons disease (PD). A structural investigation of the effect of escitalopram (a selective serotonin reuptake inhibitor) on α-synuclein was performed using ANS and ThT assays, CD, turbidity and Rayleigh scattering measurements as well as atomic force and transmission electron microscopy. Analysing the mechanism of α-synuclein fibril formation, helped us in elucidating the passage of an intermediate at 75 μM concentration of escitalopram. Fibrils of α-synuclein were obtained at 100 μM concentration of escitalopram. Inhibition of α-synuclein fibrillation was brought about by a polyphenolic acid known as caffeic acid which acted in a concentration dependent manner ranging from 10 to 60 μM. Maximum inhibition was achieved at a concentration of 60 μM. Fibrillation of α-synuclein in presence of escitalopram gives us clue for the negative effects of antidepressant. Inhibitory activity of caffeic acid against α-synuclein fibrillation may guide us in designing novel therapeutic drugs for PD.

Anti-fibrillation propensity of a flavonoid baicalein against the fibrils of hen egg white lysozyme: potential therapeutics for lysozyme amyloidosis.

More than 20 human diseases involve the fibrillation of a specific protein/peptide which forms pathological deposits at various sites. Hereditary lysozyme amyloidosis is a systemic disorder which mostly affects liver, spleen and kidney. This conformational disorder is featured by lysozyme fibril formation. In vivo lysozyme fibrillation was simulated under in vitro conditions using a strong denaturant GdHCl at 3 M concentration. Sharp decline in the ANS fluorescence intensity compared to the partially unfolded states, almost 20-fold increase in ThT fluorescence intensity, increase in absorbance at 450 nm suggesting turbidity, negative ellipticity peak in the far-UVCD at 217 nm, red shift of 50 nm compared to the native state in Congo red assay and appearance of a network of long rope-like fibrils in transmission electron microscope (TEM) analysis suggested HEWL fibrillation. Anti-fibrillation potency of baicalein against the preformed fibrils of HEWL was investigated following ThT assay in which there was a dose-dependent decrease in ThT fluorescence intensity compared to the fibrillar state of HEWL with the maximum effect observed at 150-μM baicalein concentration, loss of negative ellipticity peak in the far-UVCD region, dip in the Rayleigh scattering intensity and absorbance at 350 and 450 nm, respectively, together with a reduction in the density of fibrillar structure in TEM imaging. Thus, it could be suggested that baicalein could prove to be a positive therapeutics for hereditary human lysozyme amyloidosis. Graphical abstract

Therapeutic Interventions for the Suppression of Alzheimer’s Disease: Quest for a Remedy

Protein aggregation is facilitated by the generation of partially folded intermediates that lack most of the tertiary interactions, but retain the complete secondary structure. These partially folded states cross-link each other to form protein aggregates. Protein aggregates in an advanced stage result in the formation of amyloid fibrils, which have high tensile strength. These amyloid fibrils are associated with a number of pathologies, especially Alzheimers disease, which involves the aggregation of the Aβ peptide. In recent years, much attention has been paid to the generation of potent therapeutics to reduce Aβ peptide fibrillation. This review summarizes the range of molecules used for this therapy, showing their potency against Aβ amyloids, and suggests a positive future for the eradication of this dreaded disease.

In vitro analysis of the phytotoxic and genotoxic potential of Aligarh wastewater and Mathura refinery wastewater

Highlights • Phytotoxicity and genotoxicity suggests highly toxic nature of test wastewaters i.e. Aligarh wastewater and Mathura refinery wastewater.• The IC50 value in Allium cepa root growth inhibition test was recorded to be 0.14X and 0.10X for Mathura refinery and Aligarh industrial wastewaters, respectively.• Significant decline in the survival of various E. coli K12 DNA repair defective mutants was observed when the tester strains were exposed to the test wastewaters.• Chromosomal aberration test suggested considerable amount of chromosomal abnormalities brought about by test wastewaters.