Casein Proteins: Structural and Functional Aspects

Mammalian milk is a complex fluid mixture of various proteins, minerals, and lipids, which play an important role in providing nutrition and immunity to the newborn. Casein proteins, which form about 80% of the bovine milk proteins, form large colloidal particles with calcium phosphate to form casein micelles, which for many years have been an important subject of interest. Casein micelles are composed of four main types of proteins: αS1‐casein, αS2‐casein, β‐casein, and k‐casein. These constituent casein proteins lack well‐defined secondary and tertiary structure due to large amount of propyl residues. These micelles are being extensively studied because of their importance in functional behavior of milk and various milk products. However, the exact structure and nature of these casein micelles are still under debate. These different casein proteins possess different functional properties due to their primary amino acid sequence

C10Pred: A first machine learning based tool to predict C10 family cysteine peptidases using sequence-derived features

Streptococcus pyogenes, or group A Streptococcus (GAS), a gram-positive bacterium, is implicated in a wide range of clinical manifestations and life-threatening diseases. One of the key virulence factors of GAS is streptopain, a C10 family cysteine peptidase. Since its discovery, various homologs of streptopain have been reported from other bacterial species. With the increased affordability of sequencing, a significant increase in the number of potential C10 family-like sequences in the public databases is anticipated, posing a challenge in classifying such sequences. Sequence-similarity-based tools are the methods of choice to identify such streptopain-like sequences. However, these methods depend on some level of sequence similarity between the existing C10 family and the target sequences. Therefore, in this work, we propose a novel predictor, C10Pred, for the prediction of C10 peptidases using sequence-derived optimal features. C10Pred is a support vector machine (SVM) based model which is efficient in predicting C10 enzymes with an overall accuracy of 92.7% and Matthews’ correlation coefficient (MCC) value of 0.855 when tested on an independent dataset. We anticipate that C10Pred will serve as a handy tool to classify novel streptopain-like proteins belonging to the C10 family and offer essential information

In Vitro

Arnebia benthamii is a major ingredient of the commercial drug available under the name Gaozaban, which has antibacterial, antifungal, anti-inflammatory, and wound-healing properties. In the present study, in vitro antioxidant and anticancer activity of different extracts of Arnebia benthamii were investigated. Antioxidant potential of plant extracts was evaluated by means of total phenolics, DPPH, reducing power, microsomal lipid peroxidation, and hydroxyl radical scavenging activity. The highest phenolic content (TPC) of 780 mg GAE/g was observed in ethyl acetate, while the lowest TPC of 462 mg GAE/g was achieved in aqueous extract. At concentration of 700 µg/mL, DPPH radical scavenging activity was found to be highest in ethyl acetate extract (87.99%) and lowest in aqueous extract (73%). The reducing power of extracts increased in a concentration dependent manner. We also observed its inhibition on Fe2+/ascorbic acid-induced lipid peroxidation (LPO) on rat liver microsomes in vitro. In addition, Arnebia benthamii extracts exhibited antioxidant effects on Calf thymus DNA damage induced by Fenton reaction. Cytotoxicity of the extracts (10–100 µg/mL) was tested on five human cancer cell lines (lung, prostate, leukemia, colon, and pancreatic cell lines) using the Sulphorhodamine B assay

Amelioration of hyperglycaemia and modulation of antioxidant status by Alcea rosea seeds in alloxan-induced diabetic rats

Context: Alcea rosea L. (Malvaceae) has various medicinal uses including anticancer, anti-inflammatory and analgesic properties. However, there is no report on its antidiabetic activity. Objective: Alcea rosea seed extracts were evaluated for antihyperglycaemic and antioxidative potential in diabetic rats. Materials and methods: Single intra-peritoneal injection of alloxan (130 mg/kg b.w.) was used for induction of diabetes in Albino Wistar rats. Antihyperglycaemic and antioxidant activities of methanol and aqueous extracts of Alcea rosea seed (100 and 300 mg/kg b.w.), administered orally on daily basis for 15 days, were assessed in vivo for fasting blood glucose level and antioxidant status of liver and pancreas. Metformin was used as a positive control. Results: Aqueous and methanol extracts (300 mg/kg b.w.) decreased blood glucose level in diabetic rats by 24% and 46%, respectively. Administration of aqueous and methanol extracts at 300 mg/kg b.w. significantly (p < 0.01) modulated the antioxidant status of liver in diabetic rats by increasing levels of GR (22.5 ± 1.0, 24.4 ± 1.02 μg GSSG utilized/min/mg of protein), GPx (20.7 ± 1.2, 23.6 ± 2.04 μg GSH utilized/min/mg of protein), SOD (36.1 ± 1.7, 39.05 ± 1.5 units/mg of protein) and CAT (1744.5 ± 132.5, 1956.6 ± 125.2 nmol H2O2 decomposed/min/mg of protein), respectively. Similar results were observed for pancreas. Discussion and conclusions: Antihyperglycaemic and antioxidative potentials of Alcea rosea seeds suggest its usefulness in management of diabetes and its complications. This is the first report on antidiabetic activity of this plant

The Gut Metabolite, Trimethylamine N-oxide Inhibits Protein Folding by Affecting\u3cem\u3e Cis–trans\u3c/em\u3e Isomerization and Induces Cell Cycle Arrest

Trimethylamine N-Oxide (TMAO) is an important metabolite, which is derived from choline, betaine, and carnitine in various organisms. In humans, it is synthesized through gut microbiota and is abundantly found in serum and cerebrospinal fluid (CSF). Although TMAO is a stress protectant especially in urea-rich organisms, it is an atherogenic agent in humans and is associated with various diseases. Studies have also unveiled its exceptional role in protein folding and restoration of mutant protein functions. However, most of these data were obtained from studies carried on fast-folding proteins. In the present study, we have investigated the effect of TMAO on the folding behavior of a well-characterized protein with slow folding kinetics, carbonic anhydrase (CA). We discovered that TMAO inhibits the folding of this protein via its effect on proline cis–trans isomerization. Furthermore, TMAO is capable of inducing cell cycle arrest. This study highlights the potential role of TMAO in developing proteopathies and associated diseases

Nutritional and bioactive characteristics of buckwheat, and its potential for developing gluten-free products: An updated overview

In the present era, food scientists are concerned about exploiting functional crops with nutraceutical properties. Buckwheat is one of the functional pseudocereals with nutraceutical components used in the treatment of health-related diseases, malnutrition, and celiac diseases. As a preferred diet as a gluten-free product for celiac diseases, buckwheat is a good source of nutrients, bioactive components, phytochemicals, and antioxidants. The general characteristics and better nutritional profile of buckwheat than other cereal family crops were highlighted by previous investigations. In buckwheats, bioactive components like peptides, flavonoids, phenolic acids, d-fagomine, fagopyritols, and fagopyrins are posing significant health benefits. This study highlights the current knowledge about buckwheat and its characteristics, nutritional constituents, bioactive components, and their potential for developing gluten-free products to target celiac people (1.4% of the world population) and other health-related diseases

Brain Metabolite, Myo-inositol, Inhibits Catalase Activity: A Mechanism of the Distortion of the Antioxidant Defense System in Alzheimer’s Disease

A strong correlation between brain metabolite accumulation and oxidative stress has been observed in Alzheimer’s disease (AD) patients. There are two central hypotheses for this correlation: (i) coaccumulation of toxic amyloid-β and Myo-inositol (MI), a significant brain metabolite, during presymptomatic stages of AD, and (ii) enhanced expression of MI transporter in brain cells during oxidative stress-induced volume changes in the brain. Identifying specific interactive effects of MI with cellular antioxidant enzymes would represent an essential step in understanding the oxidative stress-induced AD pathogenicity. This study demonstrated that MI inhibits catalase, an essential antioxidant enzyme primarily inefficient in AD, by decreasing its kcat (turnover number) and increasing Km (Michaelis–Menten constant) values. This inhibition of catalase by MI under in vivo studies increased cellular H2O2 levels, leading to decreased cell viability. Furthermore, MI induces distortion of the active heme center with an overall loss of structure and stability of catalase. MI also alters distances of the vital active site and substrate channel residues of catalase. The present study provides evidence for the involvement of MI in the inactivation of the antioxidant defense system during oxidative stress-induced pathogenesis of AD. Regulation of MI levels, during early presymptomatic stages of AD, might serve as a potential early-on therapeutic strategy for this disease

Structural Characteristic of the Initial Unfolded State on Refolding Determines Catalytic Efficiency of the Folded Protein in Presence of Osmolytes

<div><p>Osmolytes are low molecular weight organic molecules accumulated by organisms to assist proper protein folding, and to provide protection to the structural integrity of proteins under denaturing stress conditions. It is known that osmolyte-induced protein folding is brought by unfavorable interaction of osmolytes with the denatured/unfolded states. The interaction of osmolyte with the native state does not significantly contribute to the osmolyte-induced protein folding. We have therefore investigated if different denatured states of a protein (generated by different denaturing agents) interact differently with the osmolytes to induce protein folding. We observed that osmolyte-assisted refolding of protein obtained from heat-induced denatured state produces native molecules with higher enzyme activity than those initiated from GdmCl- or urea-induced denatured state indicating that the structural property of the initial denatured state during refolding by osmolytes determines the catalytic efficiency of the folded protein molecule. These conclusions have been reached from the systematic measurements of enzymatic kinetic parameters (<i>K</i>_m and <i>k</i>_cat), thermodynamic stability (<i>T</i>_m and Δ<i>H</i>_m) and secondary and tertiary structures of the folded native proteins obtained from refolding of various denatured states (due to heat-, urea- and GdmCl-induced denaturation) of RNase-A in the presence of various osmolytes.</p></div