Macromolecular Assembly and Recognition with Chemical Entities

2016 ◽  
pp. 115-130
Keyword(s):  
Macromolecular Assembly

High resolution spot scan imaging of frozen, hydrated actin bundles with 400kV electrons

1992 ◽  
Vol 50 (1) ◽  
pp. 512-513
Author(s):  
J. Jakana ◽  
M.F. Schmid ◽  
P. Matsudaira ◽  
W. Chiu
Keyword(s):  
High Resolution ◽  
Binding Proteins ◽  
Actin Binding ◽  
Eukaryotic Cells ◽  
Dimensional Structure ◽  
Structural Basis ◽  
Actin Bundle ◽  
Actin Bundles ◽  
3 Dimensional ◽  
Macromolecular Assembly

Actin is a protein found in all eukaryotic cells. In its polymerized form, the cells use it for motility, cytokinesis and for cytoskeletal support. An example of this latter class is the actin bundle in the acrosomal process from the Limulus sperm. The different functions actin performs seem to arise from its interaction with the actin binding proteins. A 3-dimensional structure of this macromolecular assembly is essential to provide a structural basis for understanding this interaction in relationship to its development and functions.

Development of Synchrotron Footprinting at NSLS and NSLS-II

2019 ◽  
Vol 26 (1) ◽  
pp. 55-60 ◽  
Author(s):  
Jen Bohon
Keyword(s):  
Solvent Accessibility ◽  
Biological Systems ◽  
In Vivo Studies ◽  
Aqueous Samples ◽  
Biological Mechanisms ◽  
Macromolecular Assembly ◽  
Structure And Dynamics ◽  
Synchrotron Light ◽  
Ideal Technique

Background: First developed in the 1990’s at the National Synchrotron Light Source, xray synchrotron footprinting is an ideal technique for the analysis of solution-state structure and dynamics of macromolecules. Hydroxyl radicals generated in aqueous samples by intense x-ray beams serve as fine probes of solvent accessibility, rapidly and irreversibly reacting with solvent exposed residues to provide a “snapshot” of the sample state at the time of exposure. Over the last few decades, improvements in instrumentation to expand the technology have continuously pushed the boundaries of biological systems that can be studied using the technique. Conclusion: Dedicated synchrotron beamlines provide important resources for examining fundamental biological mechanisms of folding, ligand binding, catalysis, transcription, translation, and macromolecular assembly. The legacy of synchrotron footprinting at NSLS has led to significant improvement in our understanding of many biological systems, from identifying key structural components in enzymes and transporters to in vivo studies of ribosome assembly. This work continues at the XFP (17-BM) beamline at NSLS-II and facilities at ALS, which are currently accepting proposals for use.

scholarly journals Interfacial Crystallization and Supramolecular Self-Assembly of Spider Silk Inspired Protein at the Water-Air Interface

Materials ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4239
Author(s):  
Pezhman Mohammadi ◽  
Fabian Zemke ◽  
Wolfgang Wagermaier ◽  
Markus B. Linder
Keyword(s):  
Self Assembly ◽  
Spider Silk ◽  
Assembly Process ◽  
Protein Solution ◽  
Time Resolved ◽  
Macromolecular Assembly ◽  
X Ray Scattering ◽  
Air Interface ◽  
Fundamental Research ◽  
Β Sheet

Macromolecular assembly into complex morphologies and architectural shapes is an area of fundamental research and technological innovation. In this work, we investigate the self-assembly process of recombinantly produced protein inspired by spider silk (spidroin). To elucidate the first steps of the assembly process, we examined highly concentrated and viscous pendant droplets of this protein in air. We show how the protein self-assembles and crystallizes at the water–air interface into a relatively thick and highly elastic skin. Using time-resolved in situ synchrotron X-ray scattering measurements during the drying process, we showed that the skin evolved to contain a high β-sheet amount over time. We also found that β-sheet formation strongly depended on protein concentration and relative humidity. These had a strong influence not only on the amount, but also on the ordering of these structures during the β-sheet formation process. We also showed how the skin around pendant droplets can serve as a reservoir for attaining liquid–liquid phase separation and coacervation from the dilute protein solution. Essentially, this study shows a new assembly route which could be optimized for the synthesis of new materials from a dilute protein solution and determine the properties of the final products.

scholarly journals Homochirality Is Originated from Handedness of Helices

2020 ◽  
Author(s):  
Shubin Liu
Keyword(s):  
Amino Acids ◽  
Asymmetric Synthesis ◽  
Electrostatic Interactions ◽  
Alpha Helix ◽  
Root Cause ◽  
Macromolecular Assembly ◽  
Nucleotide Sugars ◽  
Cooperativity Effects ◽  
Natural Amino Acids ◽  
Origin Of Homochirality

Homochirality is a common feature of amino acids and carbohydrates, whose origin is still unknown. For example, 19 of 20 natural amino acids are L-chiral but deoxyribose sugars in DNA are always D-chiral. Meanwhile, right-handed helices are ubiquitous in nature. Are these two phenomena intrinsically correlated? Here, we propose that homochirality of amino acids and nucleotide sugars is originated from the handedness of helices. We show that right-handed 3<sub>10-</sub>helix and alpha-helix favor the L-chiral form for amino acids, but for deoxyribose sugars right-handed helices prefer the D-chiral form instead. Our analyses unveil that there exist strong cooperativity effects dominated by electrostatic interactions. This work not only resolves the mystery of homochirality by providing a unified explanation for the origin of homochirality in proteins and DNA using helical secondary structures as the root cause, but also ratifies the Principle of Chirality Hierarchy, where chirality of a higher hierarchy dictates that of lower ones. Possible applications of the present work to asymmetric synthesis and macromolecular assembly are discussed.

scholarly journals Dynamic Changes in Cervical Glycosaminoglycan Composition during Normal Pregnancy and Preterm Birth

Endocrinology ◽  
2012 ◽  
Vol 153 (7) ◽  
pp. 3493-3503 ◽  
Author(s):  
Yucel Akgul ◽  
Roxane Holt ◽  
Mark Mummert ◽  
Ann Word ◽  
Mala Mahendroo
Keyword(s):  
Extracellular Matrix ◽  
Preterm Birth ◽  
Normal Pregnancy ◽  
Dynamic Changes ◽  
Macromolecular Assembly ◽  
Large Structures ◽  
Ha Synthase ◽  
Metabolizing Enzyme ◽  
Induced Changes ◽  
Human Cervix

Glycosaminoglycans (GAG) have diverse functions that regulate macromolecular assembly in the extracellular matrix. During pregnancy, the rigid cervix transforms to a pliable structure to allow birth. Quantitative assessment of cervical GAG is a prerequisite to identify GAG functions in term and preterm birth. In the current study, total GAG levels increased at term, yet the abundance, chain length, and sulfation levels of sulfated GAG remained constant. The increase in total GAG resulted exclusively from an increase in hyaluronan (HA). HA can form large structures that promote increased viscosity, hydration, and matrix disorganization as well as small structures that have roles in inflammation. HA levels increased from 19% of total GAG in early pregnancy to 71% at term. Activity of the HA-metabolizing enzyme, hyaluronidase, increased in labor, resulting in metabolism of large to small HA. Similar to mice, HA transitions from high to low molecular weight in term human cervix. Mouse preterm models were also characterized by an increase in HA resulting from differential expression of the HA synthase (Has) genes, with increased Has1 in preterm in contrast to Has2 induction at term. The Has2 gene but not Has1 is regulated in part by estrogen. These studies identify a shift in sulfated GAG dominance in the early pregnant cervix to HA dominance in term and preterm ripening. Increased HA synthesis along with hyaluronidase-induced changes in HA size in mice and women suggest diverse contributions of HA to macromolecular changes in the extracellular matrix, resulting in loss of tensile strength during parturition.

scholarly journals The Mammalian Cell as a Macromolecular Assembly

2002 ◽  
Vol 2 ◽  
pp. 87-88
Author(s):  
Murray P. Deutscher ◽  
Alice Hudder ◽  
Lubov Nathanson ◽  
Romualdas Stapulionis
Keyword(s):  
Mammalian Cell ◽  
Macromolecular Assembly
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