Using diffusion distances for flexible molecular shape comparison

Background  

Many molecules are flexible and undergo significant shape deformation as part of their function, and yet most existing molecular shape comparison (MSC) methods treat them as rigid bodies, which may lead to incorrect shape recognition.     

Photoinactivation of δ-aminolevulinic acid dehydratase from maize by flavin mononuclotide

The -aminolevulinic acid dehydratase activity was irreversibly inactivated by irradiation of the enzyme in presence of flavin mononucleotide. The loss of enzyme activity was dependent on time of irradiation, concentration of FMN and intensity of irradiance. It required oxygen and was markedly enhanced in heavy water. The presence of levulinic acid (a competitive inhibitor of -ALAD) during irradiation prevented the inactivation considerably indicating photooxidative damage at or near the active site. Superoxide dismutase, sodium benzoate and sodium formate offered no protection, but singlet oxygen quenchers like azide and tryptophan were effective. NADH, electron donor to excited flavins, also prevented the loss of enzyme activity. These results indicate that singlet oxygen produced by light absorption of FMN was responsible for the photooxidative inhibition of the enzyme.Abbreviations ALAD -aminolevulinic acid dehydratase - FMN flavin mononucleotide - O₂ ^- superoxide - H₂O₂ hydrogen peroxide - 10₂ singlet oxygen - LA levulinic acid - PBG porphobilinogen - BSA bovine serum albumin - BME 2-mercaptoethanol - SOD superoxide dismutase - pHMB para-hydroxymercuribenzoate - DTT dithiothreitol - FAD flavin adenine dinucleotide - NADH nicotinamide adenine dinucleotide     

Use of diethyl squarate for the coupling of oligosaccharide amines to carrier proteins and characterization of the resulting neoglycoproteins by MALDI-TOF mass spectrometry

The 8-methoxycarbonyloctyl glycosides of GlcNAc, Gal1-4Glc, Fuc1-2Fuc1-3GalNac and Fuc1-2Gal1-3[Fuc1-4]GlcNac were converted to primary amines by reaction with neat ethylenediamine and then coupled to bovine serum albumin (BSA) using diethyl squarate as the connector. The average degree of incorporation of the sugar onto the protein, as well as the molecular weight distribution, could be conveniently determined using matrix assisted laser desorption ionization/time of flight (MALDI-TOF) mass spectrometry thus avoiding cumbersome structure-dependent colour-tests or analysis of cleaved ligand. The present coupling method has the advantages of proceeding under very mild conditions, yielding controlled incorporation values and can reliably be used for the coupling of very small amounts (mg) of oligosaccharide.This paper is dedicated to Sen-itiroh Hakomori on the occasion of his 65th birthday     

A neurological integrator for the oculomotor control system

This paper describes a mathematical model of a neurological integrator that has been developed to provide the very long leakage time constant required of the intgrator in the oculomotor system. The Gaussian distribution of cell thresholds and the eye-position- related discharge of the individual cells of the integrator model, and the highly specialized short-duration, high-frequency burst required of the input, have been modeled after the single-cell behavior actually observed in the oculomotor control areas of the brain stem of an alert primate.     

Development and Validation of Real-Time PCR for Rapid Detection of Mecistocirrus digitatus

Hematophagous activity of Mecistocirrus digitatus, which causes substantial blood and weight loss in large ruminants, is an emerging challenge due to the economic loss it brings to the livestock industry. Infected animals are treated with anthelmintic drugs, based on the identification of helminth species and the severity of infection; however, traditional methods such as microscopic identification and the counting of eggs for diagnosis and determination of level of infection are laborious, cumbersome and unreliable. To facilitate the detection of this parasite, a SYBR green-based real-time PCR was standardized and validated for the detection of M. digitatus infection in cattle and buffaloes. Oligonucleotides were designed to amplify partial Internal Transcribed Spacer (ITS)-1 sequence of M. digitatus. The specificity of the primers was confirmed by non-amplification of DNA extracted from other commonly occurring gastrointestinal nematodes in ruminants. Plasmids were ligated with partial ITS-1 sequence of M. digitatus, serially diluted (hundred fold) and used as standards in the real-time PCR assay. The quantification cycle (Cq) values were plotted against the standard DNA concentration to produce a standard curve. The assay was sensitive enough to detect one plasmid containing the M. digitatus DNA. Clinical application of this assay was validated by testing the DNA extracted from the faeces of naturally infected cattle (n = 40) and buffaloes (n = 25). The results were compared with our standard curve to calculate the quantity of M. digitatus in each faecal sample. The Cq value of the assay depicted a strong linear relationship with faecal DNA content, with a regression coefficient of 0.984 and efficiency of 99%. This assay has noteworthy advantages over the conventional methods of diagnosis because it is more specific, sensitive and reliable.     

Purification,Characterization and Antibacterial Properties of Peptide from Marine Ascidian Didemnum sp.

International Journal of Peptide Research and Therapeutics - Marine ecosystems are unique and a largely diverse chest of natural resources which are still to be explored for new marine species....     

A five‐step risk management process for geriatric dental practice during SARS‐CoV‐2 pandemic

Severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) is an RNA virus that causes coronavirus infection (COVID‐19). COVID‐19 is a highly contagious disease transmitted through respiratory droplets, saliva and other contact routes. Within 10 months of its outbreak, SARS‐CoV‐2 has infected more than 23 million people around the world. Evidence suggests that older adults are the most vulnerable to infection and have an increased risk of mortality. Reduced immunity and underlying medical conditions make them risk‐prone and vulnerable to critical care. Older adults affected with the SARS‐CoV‐2 virus present with distinct clinical manifestations necessitating specific treatment needs and management protocols. While it is crucial to prevent the spread of novel coronavirus (2019‐nCoV), the role of oral healthcare workers in addressing the specific needs of ageing adult patients by adopting specific guidelines and appropriate infection control protocols is timely. This paper aims to develop specific guidelines and protocols for the dental management of geriatric patients during the COVID‐19 pandemic.     

Fibrillation of Human Calcitonin and Its Analogs: Effects of Phosphorylation and Disulfide Reduction

Some therapeutic peptides self-assemble in solution to form ordered, insoluble, β-sheet-rich amyloid fibrils. This physical instability can result in reduced potency, cause immunogenic side effects, and limit options for formulation. Understanding the mechanisms of fibrillation is key to developing rational mitigation strategies. Here, amide hydrogen-deuterium exchange with mass spectrometric analysis (HDX-MS) coupled with proteolytic digestion was used to identify the early stage interactions leading to fibrillation of human calcitonin (hCT), a peptide hormone important in calcium metabolism. hCT fibrillation kinetics was sigmoidal, with lag, growth, and plateau phases as shown by thioflavin T and turbidity measurements. HDX-MS of fibrillating hCT (pH 7.4; 25°C) suggested early involvement of the N-terminal (1–11) and central (12–19) fragments in interactions during the lag phase, whereas C-terminal fragments (20–32 and 26–32) showed limited involvement during this period. The residue-level information was used to develop phosphorylated hCT analogs that showed modified fibrillation that depended on phosphorylation site. Phosphorylation in the central region resulted in complete inhibition of fibrillation for the phospho-Thr-13 hCT analog, whereas phosphorylation in the N-terminal and C-terminal regions inhibited but did not prevent fibrillation. Reduction of the Cys1-Cys7 disulfide bond resulted in faster fibrillation with involvement of different hCT residues as indicated by pulsed HDX-MS. Together, the results demonstrate that small structural changes have significant effects on hCT fibrillation and that understanding these effects can inform the rational development of fibrillation-resistant hCT analogs.     

Improved in planta genetic transformation efficiency in bitter gourd (Momordica charantia L.)

In Vitro Cellular & Developmental Biology - Plant - Production of transformed bitter gourd plants through in vitro regeneration is a laborious practice, which may also result in somaclonal...