scholarly journals Exploring the influence of silver and lead on structure and function of xylanase: spectroscopic and calorimetric methods

2020 ◽  
Vol 9 (3) ◽  
pp. 182-190
Author(s):  
Mingyang Jing ◽  
Rui Tang ◽  
Guangye Han ◽  
Shansheng Zhang ◽  
Rutao Liu
Keyword(s):  
Enzymatic Activity ◽  
Molecular Level ◽  
Structure And Function ◽  
Titration Calorimetry ◽  
Soil Enzyme Activities ◽  
Hydrophobic Force ◽  
Negative Effect ◽  
Endogenous Fluorescence ◽  
Underlying Mechanisms ◽  
And Function

Abstract Soil contamination with heavy metal could induce the alteration of soil ecological environments, and soil enzyme activities are sensitive indicators for the soil toxicology. Xylanase is one of predominant soil enzymes related to carbon nitrogen cycle. In this work, we explored the underlying mechanisms for conformational and enzymatic activity alterations of xylanase after silver and lead exposure at molecular level with systematical measurements including multiple spectroscopic methods, isothermal titration calorimetry, and enzymatic activity. Both silver and lead could loosen and unfold the skeleton of xylanase with the quenching of endogenous fluorescence. Silver interacted with xylanase forming larger-size aggregations through Van der Waals forces and hydrogen bonding, while lead interacted with xylanase forming larger-size aggregations through hydrophobic force. Silver and lead induced an obvious loss (67.1 and 56.31%) of the xylanase enzymatic activity, but silver has a greater impact on xylanase than that of lead. The xylanase enzymatic activity significantly decreased due to the conformational alterations. The negative effect of silver exposure on xylanase structure and function was more prominent than that of lead.

scholarly journals The encapsulin from Thermatoga maritima is a flavoprotein with a symmetry matched ferritin-like cargo protein

2021 ◽  
Author(s):  
Benjamin J LaFrance ◽  
Caleb Cassidy-Amstutz ◽  
Robert J Nichols ◽  
Luke M Oltrogge ◽  
Eva Nogales ◽  
...  
Keyword(s):  
Enzymatic Activity ◽  
Biochemical Analysis ◽  
Active Role ◽  
Structure And Function ◽  
Redox Active ◽  
Cargo Protein ◽  
Cargo Proteins ◽  
And Function ◽  
Flavin Binding ◽  
Unique Chemical

Bacterial nanocompartments, also known as encapsulins, are an emerging class of protein-based "organelles" found in bacteria and archaea. Encapsulins are virus-like icosahedral particles comprising a ~25-50 nm shell surrounding a specific cargo enzyme. Compartmentalization is thought to create a unique chemical environment to facilitate catalysis and isolate toxic intermediates. Many questions regarding nanocompartment structure-function remain unanswered, including how shell symmetry dictates cargo loading and to what extent the shell facilitates enzymatic activity. Here, we explore these questions using the model T. maritima nanocompartment known to encapsulate a redox-active ferritin-like protein. Biochemical analysis revealed the encapsulin shell to possess a flavin binding site located at the interface between capsomere subunits, suggesting the shell may play a direct and active role in the function of the encapsulated cargo. Furthermore, we used cryoEM to show that cargo proteins use a form of symmetry-matching to facilitate encapsulation and define stoichiometry. In the case of the T. maritima encapsulin, the decameric cargo protein with 5-fold symmetry preferentially binds to the pentameric-axis of the icosahedral shell. Taken together, these observations suggest the shell is not simply a passive barrier-it also plays a significant role in the structure and function of the cargo enzyme.

Structure and function of channel-forming peptaibols

1993 ◽  
Vol 26 (4) ◽  
pp. 365-421 ◽  
Author(s):  
M. S. P. Sansom
Keyword(s):  
Electrical Properties ◽  
Molecular Level ◽  
Structure And Function ◽  
Atomic Resolution ◽  
Excitable Cells ◽  
Channel Proteins ◽  
Physiological Processes ◽  
Transport Of Ions ◽  
And Function

Transport of ions through channels is fundamental to a number of physiological processes, especially the electrical properties of excitable cells (Hille, 1992). To understand this process at a molecular level requires atomic resolution structures of channel proteins.

A replicative and synthetic chromosomal unit-the modern concept of the chromomere

1966 ◽  
Vol 164 (995) ◽  
pp. 279-289 ◽  
Keyword(s):  
Molecular Level ◽  
Structure And Function ◽  
Structural Basis ◽  
Modern Concept ◽  
Chromosomal Structure ◽  
New Approaches ◽  
Combined Use ◽  
And Function

present-day discussions on chromosomal structure and function the old term chromomere’ (Fol 1891) is seldom mentioned and it may be debated whether at is still desirable to use such a term. Conventionally it describes the bead-like concentrations of chromatin linearly arranged along the chromosomal thread, without implications as to the structural basis of such a discontinuity. Two alternative interpretations of the chromomeric organization of the chromosome have been suggested, one in which the chromomeres were regarded as definite chromosomal bodies, different from the interchromomeric regions of the chromosome, and one which considered the chromomeres as structures resulting only from the local coiling of a continuous chromosomal thread. Neither the chromomere hypothesis (Belling 1928; Bridges 1935; Pontecorvo 1944) nor the chromonema hypothesis (Ris 1945) has been finally and universally accepted. This is because the morphological and cytogenetical evidence previously available was insufficient to extend our knowledge of chromosomal structure down to the molecular level. New approaches in this direction have recently been made by the combined use of cytological, autoradiographic and photometric methods. They draw new attention to the chromomere.

scholarly journals Current understanding of cortical structure and function in migraine

Cephalalgia ◽  
2019 ◽  
Vol 39 (13) ◽  
pp. 1683-1699 ◽  
Author(s):  
Else A Tolner ◽  
Shih-Pin Chen ◽  
Katharina Eikermann-Haerter
Keyword(s):  
Structure And Function ◽  
Dynamic Interactions ◽  
Therapeutic Implications ◽  
Functional Changes ◽  
Cortical Structure ◽  
Modifying Factors ◽  
Subcortical Regions ◽  
Underlying Mechanisms ◽  
Cortical Regions ◽  
And Function

Objective To review and discuss the literature on the role of cortical structure and function in migraine. Discussion Structural and functional findings suggest that changes in cortical morphology and function contribute to migraine susceptibility by modulating dynamic interactions across cortical and subcortical networks. The involvement of the cortex in migraine is well established for the aura phase with the underlying phenomenon of cortical spreading depolarization, while increasing evidence suggests an important role for the cortex in perception of head pain and associated sensations. As part of trigeminovascular pain and sensory processing networks, cortical dysfunction is likely to also affect initiation of attacks. Conclusion Morphological and functional changes identified across cortical regions are likely to contribute to initiation, cyclic recurrence and chronification of migraine. Future studies are needed to address underlying mechanisms, including interactions between cortical and subcortical regions and effects of internal (e.g. genetics, gender) and external (e.g. sensory inputs, stress) modifying factors, as well as possible clinical and therapeutic implications.

scholarly journals N-linked Oligosaccharides Affect the Enzymatic Activity of CD39: Diverse Interactions between Seven N-linked Glycosylation Sites

2005 ◽  
Vol 16 (4) ◽  
pp. 1661-1672 ◽  
Author(s):  
James J. Wu ◽  
Lisa E. Choi ◽  
Guido Guidotti
Keyword(s):  
Enzymatic Activity ◽  
Surface Expression ◽  
Structure And Function ◽  
Surface Appearance ◽  
C Terminus ◽  
Glycosylation Sites ◽  
N Terminus ◽  
Membrane Bound ◽  
And Function ◽  
Diverse Interactions

Rat CD39, a membrane-bound ectonucleoside triphosphate diphosphohydrolase that hydrolyzes extracellular nucleoside tri- and diphosphates, has seven potential N-glycosylation sites at asparagine residues 73, 226, 291, 333, 375, 429, and 458. To determine their roles in the structure and function of CD39, we mutated these sites individually or in combination by replacing asparagine with serine or glutamine and analyzed the surface expression and the enzymatic activity of the mutants. The results indicate that rat CD39 can be glycosylated at all seven sites when expressed in COS7 cells. Glycosylation sites 73 at the N terminus, 333 in the middle, and 429 and 458 at the C terminus were principally required for cell surface appearance of enzymatically active CD39. Whereas deletion of these sites individually had modest effects on surface ATPase activity, some double deletions of these sites had major effects on both surface activity and expression. The importance of these N-glycosylation sites is recognizable in other members of the ectonucleoside triphosphate diphosphohydrolase family.

scholarly journals Toxic Effect Induced by Cadmium on Some Reproductive Parameters and the Therapeutic Role of Leaves of Lemon Verbena: الأثر السمّي المستحدث بعنصر الكادميوم على بعض المعايير التكاثرية والدور العلاجي لأوراق نبات المليسة

2021 ◽  
Vol 5 (5) ◽  
pp. 14-1
Author(s):  
Mohammad Amer Salaho, Mahmoud Kassem Mohammad Amer Salaho, Mahmoud Kassem
Keyword(s):  
Cadmium Toxicity ◽  
Structure And Function ◽  
Control Group ◽  
Alcoholic Extract ◽  
Reproductive Parameters ◽  
Cadmium Treatment ◽  
Negative Effect ◽  
And Function ◽  
Lemon Verbena

This study was conducted on 28 male Syrian hamsters, and the aim was to confirm the toxic effects of cadmium on the structure and function of the male reproductive system and to test the effectiveness of the alcoholic extract of the lemon verbena plant in the therapeutic of cadmium toxicity. The results of the study showed the negative effect of cadmium on some reproductive parameters of male Syrian Hamster, where treatment with cadmium (5mg/kg/day) reduced GSI% values ​​for both testis and epididymis, lowered the values ​​of testicular dimensions, testosterone concentration and some physiological parameters of the tail of the epididymis sperm and some histological measurements for testes, numbers of spermatogenesis cells, Sertoli and Leydig, cadmium treatment caused histological disorders in the testicles, compared to the control group. Dosing male hamsters with lemon verbena leaf extract at two concentrations (250,500mg/kg/day) did not lead to a clear improvement compared to the cadmium group.

scholarly journals Current Understanding of the Right Ventricle Structure and Function in Pulmonary Arterial Hypertension

2021 ◽  
Vol 12 ◽  
Author(s):  
Danial Sharifi Kia ◽  
Kang Kim ◽  
Marc A. Simon
Keyword(s):  
Pulmonary Arterial Hypertension ◽  
Arterial Hypertension ◽  
Structure And Function ◽  
Biomechanical Analysis ◽  
Current Understanding ◽  
Future Research ◽  
Close Link ◽  
Pulmonary Arterial ◽  
Underlying Mechanisms ◽  
And Function

Pulmonary arterial hypertension (PAH) is a disease resulting in increased right ventricular (RV) afterload and RV remodeling. PAH results in altered RV structure and function at different scales from organ-level hemodynamics to tissue-level biomechanical properties, fiber-level architecture, and cardiomyocyte-level contractility. Biomechanical analysis of RV pathophysiology has drawn significant attention over the past years and recent work has found a close link between RV biomechanics and physiological function. Building upon previously developed techniques, biomechanical studies have employed multi-scale analysis frameworks to investigate the underlying mechanisms of RV remodeling in PAH and effects of potential therapeutic interventions on these mechanisms. In this review, we discuss the current understanding of RV structure and function in PAH, highlighting the findings from recent studies on the biomechanics of RV remodeling at organ, tissue, fiber, and cellular levels. Recent progress in understanding the underlying mechanisms of RV remodeling in PAH, and effects of potential therapeutics, will be highlighted from a biomechanical perspective. The clinical relevance of RV biomechanics in PAH will be discussed, followed by addressing the current knowledge gaps and providing suggested directions for future research.

scholarly journals Mapping Meditative States and Stages with Electrophysiology: Concepts, Classifications, and Methods

2018 ◽  
Author(s):  
Poppy Schoenberg ◽  
David R Vago
Keyword(s):  
Structure And Function ◽  
Human Consciousness ◽  
Biological Structure ◽  
Contemplative Practices ◽  
States Of Consciousness ◽  
Neurobiological Substrates ◽  
Underlying Mechanisms ◽  
And Function ◽  
The Mind ◽  
The Brain

Exploration of human consciousness remains a final frontier within basic neuroscience; that is, how the finite biological structure and function of the brain gives rise to the seemingly infinite expanse that encompasses the terrain of the mind. Contemporary mindfulness and other contemplative practices across historical and post-modern traditions involve systematic forms of mental training that allow the practitioner to develop the mind in very specific and quantifiable ways. Some fundamental questions pertain to this scientific enquiry; (1) how to concisely classify discrete and developmentally-specific “mind states” of consciousness that are in line with the subtle complex phenomenology of experience so to yield ontological quantifications? (2) what measures best represent such classification/quantification systems? (3) can the present electrophysiological purview map developmentally-specified mind states and stages to neurobiological substrates, based on extant contention (i.e. discrete EEG band functionality, phenomenological significance, and underlying mechanisms) regarding the interpretation of EEG physiology?

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