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1.
Ultrafast Fluorescence Spectroscopy via Upconversion and Its Applications in Biophysics.
Cao, S, Li, H, Zhao, Z, Zhang, S, Chen, J, Xu, J, Knutson, JR, Brand, L
Molecules (Basel, Switzerland). 2021;(1)
Abstract
In this review, the experimental set-up and functional characteristics of single-wavelength and broad-band femtosecond upconversion spectrophotofluorometers developed in our laboratory are described. We discuss applications of this technique to biophysical problems, such as ultrafast fluorescence quenching and solvation dynamics of tryptophan, peptides, proteins, reduced nicotinamide adenine dinucleotide (NADH), and nucleic acids. In the tryptophan dynamics field, especially for proteins, two types of solvation dynamics on different time scales have been well explored: ~1 ps for bulk water, and tens of picoseconds for "biological water", a term that combines effects of water and macromolecule dynamics. In addition, some proteins also show quasi-static self-quenching (QSSQ) phenomena. Interestingly, in our more recent work, we also find that similar mixtures of quenching and solvation dynamics occur for the metabolic cofactor NADH. In this review, we add a brief overview of the emerging development of fluorescent RNA aptamers and their potential application to live cell imaging, while noting how ultrafast measurement may speed their optimization.
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Site-Selective, Chemical Modification of Protein at Aromatic Side Chain and Their Emergent Applications.
Chowdhury, A, Chatterjee, S, Pongen, A, Sarania, D, Tripathi, NM, Bandyopadhyay, A
Protein and peptide letters. 2021;(7):788-808
Abstract
Site-selective chemical modification of protein side chain has probed enormous opportunities in the fundamental understanding of cellular biology and therapeutic applications. Primarily, in the field of biopharmaceuticals, the formulation of bioconjugates has been found to have more potential than an individual constituent. In this regard, Lysine and Cysteine are the most widely used endogenous amino acid for these purposes. Recently, the aromatic side chain residues (Trp, Tyr, and His) that are low abundant in protein have gained more attention in therapeutic applications due to their advantages of chemical reactivity and specificity. This review discusses the site-selective bioconjugation methods for aromatic side chains (Trp, Tyr and His) and highlights the developed strategies in the last three years, along with their applications. Also, the review highlights the prevalent methods published earlier. We have examined that metal-catalyzed and photocatalytic reactions are gaining more attention for bioconjugation, though their practical operation is under development. The review has been summarized with the future perspective of protein and peptide conjugations contemplating therapeutic applications and challenges.
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3.
Initiation and Prevention of Biological Damage by Radiation-Generated Protein Radicals.
Gebicki, JM, Nauser, T
International journal of molecular sciences. 2021;(1)
Abstract
Ionizing radiations cause chemical damage to proteins. In aerobic aqueous solutions, the damage is commonly mediated by the hydroxyl free radicals generated from water, resulting in formation of protein radicals. Protein damage is especially significant in biological systems, because proteins are the most abundant targets of the radiation-generated radicals, the hydroxyl radical-protein reaction is fast, and the damage usually results in loss of their biological function. Under physiological conditions, proteins are initially oxidized to carbon-centered radicals, which can propagate the damage to other molecules. The most effective endogenous antioxidants, ascorbate, GSH, and urate, are unable to prevent all of the damage under the common condition of oxidative stress. In a promising development, recent work demonstrates the potential of polyphenols, their metabolites, and other aromatic compounds to repair protein radicals by the fast formation of less damaging radical adducts, thus potentially preventing the formation of a cascade of new reactive species.
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4.
iPhosH-PseAAC: Identify Phosphohistidine Sites in Proteins by Blending Statistical Moments and Position Relative Features According to the Chou's 5-Step Rule and General Pseudo Amino Acid Composition.
Awais, M, Hussain, W, Khan, YD, Rasool, N, Khan, SA, Chou, KC
IEEE/ACM transactions on computational biology and bioinformatics. 2021;(2):596-610
Abstract
Protein phosphorylation is one of the key mechanism in prokaryotes and eukaryotes and is responsible for various biological functions such as protein degradation, intracellular localization, the multitude of cellular processes, molecular association, cytoskeletal dynamics, and enzymatic inhibition/activation. Phosphohistidine (PhosH) has a key role in a number of biological processes, including central metabolism to signalling in eukaryotes and bacteria. Thus, identification of phosphohistidine sites in a protein sequence is crucial, and experimental identification can be expensive, time-taking, and laborious. To address this problem, here, we propose a novel computational model namely iPhosH-PseAAC for prediction of phosphohistidine sites in a given protein sequence using pseudo amino acid composition (PseAAC), statistical moments, and position relative features. The results of the proposed predictor are validated through self-consistency testing, 10-fold cross-validation, and jackknife testing. The self-consistency validation gave the 100 percent accuracy, whereas, for cross-validation, the accuracy achieved is 94.26 percent. Moreover, jackknife testing gave 97.07 percent accuracy for the proposed model. Thus, the proposed model iPhosH-PseAAC for prediction of iPhosH site has the great ability to predict the PhosH sites in given proteins.
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5.
Starvation Ketosis and the Kidney.
Palmer, BF, Clegg, DJ
American journal of nephrology. 2021;(6):467-478
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Abstract
BACKGROUND The remarkable ability of the body to adapt to long-term starvation has been critical for survival of primitive man. An appreciation of these processes can provide the clinician better insight into many clinical conditions characterized by ketoacidosis. SUMMARY The body adapts to long-term fasting by conserving nitrogen, as the brain increasingly utilizes keto acids, sparing the need for glucose. This shift in fuel utilization decreases the need for mobilization of amino acids from the muscle for purposes of gluconeogenesis. Loss of urinary nitrogen is initially in the form of urea when hepatic gluconeogenesis is dominant and later as ammonia reflecting increased glutamine uptake by the kidney. The carbon skeleton of glutamine is utilized for glucose production and regeneration of consumed HCO3-. The replacement of urea with NH4+ provides the osmoles needed for urine flow and waste product excretion. Over time, the urinary loss of nitrogen is minimized as kidney uptake of filtered ketone bodies becomes more complete. Adjustments in urine Na+ serve to minimize kidney K+ wasting and, along with changes in urine pH, minimize the likelihood of uric acid precipitation. There is a sexual dimorphism in response to starvation. Key Message: Ketoacidosis is a major feature of common clinical conditions to include diabetic ketoacidosis, alcoholic ketoacidosis, salicylate intoxication, SGLT2 inhibitor therapy, and calorie sufficient but carbohydrate-restricted diets. Familiarity with the pathophysiology and metabolic consequences of ketogenesis is critical, given the potential for the clinician to encounter one of these conditions.
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SecProCT: In Silico Prediction of Human Secretory Proteins Based on Capsule Network and Transformer.
Du, W, Zhao, X, Sun, Y, Zheng, L, Li, Y, Zhang, Y
International journal of molecular sciences. 2021;(16)
Abstract
Identifying secretory proteins from blood, saliva or other body fluids has become an effective method of diagnosing diseases. Existing secretory protein prediction methods are mainly based on conventional machine learning algorithms and are highly dependent on the feature set from the protein. In this article, we propose a deep learning model based on the capsule network and transformer architecture, SecProCT, to predict secretory proteins using only amino acid sequences. The proposed model was validated using cross-validation and achieved 0.921 and 0.892 accuracy for predicting blood-secretory proteins and saliva-secretory proteins, respectively. Meanwhile, the proposed model was validated on an independent test set and achieved 0.917 and 0.905 accuracy for predicting blood-secretory proteins and saliva-secretory proteins, respectively, which are better than conventional machine learning methods and other deep learning methods for biological sequence analysis. The main contributions of this article are as follows: (1) a deep learning model based on a capsule network and transformer architecture is proposed for predicting secretory proteins. The results of this model are better than the those of existing conventional machine learning methods and deep learning methods for biological sequence analysis; (2) only amino acid sequences are used in the proposed model, which overcomes the high dependence of existing methods on the annotated protein features; (3) the proposed model can accurately predict most experimentally verified secretory proteins and cancer protein biomarkers in blood and saliva.
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Short-Term Pre-Operative Protein Caloric Restriction in Elective Vascular Surgery Patients: A Randomized Clinical Trial.
Kip, P, Sluiter, TJ, Moore, JK, Hart, A, Ruske, J, O'Leary, J, Jung, J, Tao, M, MacArthur, MR, Heindel, P, et al
Nutrients. 2021;(11)
Abstract
(1) Background: Vascular surgery operations are hampered by high failure rates and frequent occurrence of peri-operative cardiovascular complications. In pre-clinical studies, pre-operative restriction of proteins and/or calories (PCR) has been shown to limit ischemia-reperfusion damage, slow intimal hyperplasia, and improve metabolic fitness. However, whether these dietary regimens are feasible and safe in the vascular surgery patient population remains unknown. (2) Methods: We performed a randomized controlled trial in patients scheduled for any elective open vascular procedure. Participants were randomized in a 3:2 ratio to either four days of outpatient pre-operative PCR (30% calorie, 70% protein restriction) or their regular ad-libitum diet. Blood was drawn at baseline, pre-operative, and post-operative day 1 timepoints. A leukocyte subset flow cytometry panel was performed at these timepoints. Subcutaneous/perivascular adipose tissue was sampled and analyzed. Follow-up was one year post-op. (3) Results: 19 patients were enrolled, of whom 11 completed the study. No diet-related reasons for non-completion were reported, and there was no intervention group crossover. The PCR diet induced weight loss and BMI decrease without malnutrition. Insulin sensitivity was improved after four days of PCR (p = 0.05). Between diet groups, there were similar rates of re-intervention, wound infection, and cardiovascular complications. Leukocyte populations were maintained after four days of PCR. (4) Conclusions: Pre-operative PCR is safe and feasible in elective vascular surgery patients.
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Essential amino acid-enriched whey enhances post-exercise whole-body protein balance during energy deficit more than iso-nitrogenous whey or a mixed-macronutrient meal: a randomized, crossover study.
Gwin, JA, Church, DD, Hatch-McChesney, A, Allen, JT, Wilson, MA, Varanoske, AN, Carrigan, CT, Murphy, NE, Margolis, LM, Carbone, JW, et al
Journal of the International Society of Sports Nutrition. 2021;(1):4
Abstract
BACKGROUND The effects of ingesting varying essential amino acid (EAA)/protein-containing food formats on protein kinetics during energy deficit are undetermined. Therefore, recommendations for EAA/protein food formats necessary to optimize both whole-body protein balance and muscle protein synthesis (MPS) during energy deficit are unknown. We measured protein kinetics after consuming iso-nitrogenous amounts of free-form essential amino acid-enriched whey (EAA + W; 34.7 g protein, 24 g EAA sourced from whey and free-form EAA), whey (WHEY; 34.7 g protein, 18.7 g EAA), or a mixed-macronutrient meal (MEAL; 34.7 g protein, 11.4 g EAA) after exercise during short-term energy deficit. METHODS Ten adults (mean ± SD; 21 ± 4 y; 25.7 ± 1.7 kg/m2) completed a randomized, double-blind crossover study consisting of three, 5 d energy-deficit periods (- 30 ± 3% of total energy requirements), separated by 14 d. Whole-body protein synthesis (PS), breakdown (PB), and net balance (NET) were determined at rest and in response to combination exercise consisting of load carriage treadmill walking, deadlifts, and box step-ups at the end of each energy deficit using L-[2H5]-phenylalanine and L-[2H2]-tyrosine infusions. Treatments were ingested immediately post-exercise. Mixed-muscle protein synthesis (mixed-MPS) was measured during exercise through recovery. RESULTS Change (Δ postabsorptive + exercise to postprandial + recovery [mean treatment difference (95%CI)]) in whole-body (g/180 min) PS was 15.8 (9.8, 21.9; P = 0.001) and 19.4 (14.8, 24.0; P = 0.001) greater for EAA + W than WHEY and MEAL, respectively, with no difference between WHEY and MEAL. ΔPB was - 6.3 (- 11.5, - 1.18; P = 0.02) greater for EAA + W than WHEY and - 7.7 (- 11.9, - 3.6; P = 0.002) greater for MEAL than WHEY, with no difference between EAA + W and MEAL. ΔNET was 22.1 (20.5, 23.8; P = 0.001) and 18.0 (16.5, 19.5; P = 0.00) greater for EAA + W than WHEY and MEAL, respectively, while ΔNET was 4.2 (2.7, 5.6; P = 0.001) greater for MEAL than WHEY. Mixed-MPS did not differ between treatments. CONCLUSIONS While mixed-MPS was similar across treatments, combining free-form EAA with whey promotes greater whole-body net protein balance during energy deficit compared to iso-nitrogenous amounts of whey or a mixed-macronutrient meal. TRIAL REGISTRATION ClinicalTrials.gov, Identifier no. NCT04004715 . Retrospectively registered 28 June 2019, first enrollment 6 June 2019.
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Optical Configuration Effect on the Structure and Reactivity of Diastereomers Revealed by Spin Effects and Molecular Dynamics Calculations.
Ageeva, AA, Doktorov, AB, Selyutina, OY, Magin, IM, Ilyina, MG, Borisevich, SS, Rubtsov, RY, Khursan, SL, Stepanov, AA, Vasilevsky, SF, et al
International journal of molecular sciences. 2021;(1)
Abstract
The peculiarities of spin effects in photoinduced electron transfer (ET) in diastereomers of donor-acceptor dyads are considered in order to study the influence of chirality on reactivity. Thus, the spin selectivity-the difference between the enhancement coefficients of chemically induced dynamic nuclear polarization (CIDNP)-of the dyad's diastereomers reflects the difference in the spin density distribution in its paramagnetic precursors that appears upon UV irradiation. In addition, the CIDNP coefficient itself has demonstrated a high sensitivity to the change of chiral centers: when one center is changed, the hyperpolarization of all polarized nuclei of the molecule is affected. The article analyzes the experimental values of spin selectivity based on CIDNP calculations and molecular dynamic modeling data in order to reveal the effect of optical configuration on the structure and reactivity of diastereomers. In this way, we succeeded in tracing the differences in dyads with L- and D-tryptophan as an electron donor. Since the replacement of L-amino acid with D-analog in specific proteins is believed to be the cause of Alzheimer's and Parkinson's diseases, spin effects and molecular dynamic simulation in model dyads can be a useful tool for investigating the nature of this phenomenon.
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Electron inventory of the iron-sulfur scaffold complex HypCD essential in [NiFe]-hydrogenase cofactor assembly.
Stripp, ST, Oltmanns, J, Müller, CS, Ehrenberg, D, Schlesinger, R, Heberle, J, Adrian, L, Schünemann, V, Pierik, AJ, Soboh, B
The Biochemical journal. 2021;(17):3281-3295
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Abstract
The [4Fe-4S] cluster containing scaffold complex HypCD is the central construction site for the assembly of the [Fe](CN)2CO cofactor precursor of [NiFe]-hydrogenase. While the importance of the HypCD complex is well established, not much is known about the mechanism by which the CN- and CO ligands are transferred and attached to the iron ion. We report an efficient expression and purification system producing the HypCD complex from E. coli with complete metal content. This enabled in-depth spectroscopic characterizations. The results obtained by EPR and Mössbauer spectroscopy demonstrate that the [Fe](CN)2CO cofactor and the [4Fe-4S] cluster of the HypCD complex are redox active. The data indicate a potential-dependent interconversion of the [Fe]2+/3+ and [4Fe-4S]2+/+ couple, respectively. Moreover, ATR FTIR spectroscopy reveals potential-dependent disulfide formation, which hints at an electron confurcation step between the metal centers. MicroScale thermophoresis indicates preferable binding between the HypCD complex and its in vivo interaction partner HypE under reducing conditions. Together, these results provide comprehensive evidence for an electron inventory fit to drive multi-electron redox reactions required for the assembly of the CN- and CO ligands on the scaffold complex HypCD.