skip to main content
US FlagAn official website of the United States government
dot gov icon
Official websites use .gov
A .gov website belongs to an official government organization in the United States.
https lock icon
Secure .gov websites use HTTPS
A lock ( lock ) or https:// means you've safely connected to the .gov website. Share sensitive information only on official, secure websites.

Explore Research Products in the PAR
It may take a few hours for recently added research products to appear in PAR search results.


Title: Ice-Binding Protein from Shewanella frigidimarinas Inhibits Ice Crystal Growth in Highly Alkaline Solutions
The ability of a natural ice-binding protein from Shewanella frigidimarina (SfIBP) to inhibit ice crystal growth in highly alkaline solutions with increasing pH and ionic strength was investigated in this work. The purity of isolated SfIBP was first confirmed via sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and size-exclusion chromatography with an ultraviolet detector (SEC-UV). Protein stability was evaluated in the alkaline solutions using circular dichroism spectroscopy, SEC-UV, and SDS-PAGE. SfIBP ice recrystallization inhibition (IRI) activity, a measure of ice crystal growth inhibition, was assessed using a modified splat assay. Statistical analysis of results substantiated that, despite partial denaturation and misfolding, SfIBP limited ice crystal growth in alkaline solutions (pH ≤ 12.7) with ionic strength I ≤ 0.05 mol/L, but did not exhibit IRI activity in alkaline solutions where pH ≥ 13.2 and I ≥ 0.16 mol/L. IRI activity of SfIBP in solutions with pH ≤ 12.7 and I ≤ 0.05 mol/L demonstrated up to ≈ 66% reduction in ice crystal size compared to neat solutions.  more » « less
Award ID(s):
1727788
PAR ID:
10100495
Author(s) / Creator(s):
; ; ; ; ;
Date Published:
Journal Name:
Polymers
Volume:
11
Issue:
2
ISSN:
2073-4360
Page Range / eLocation ID:
299
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
More Like this
  1. ; ; (, Sustainable Food Proteins)
    Abstract Soy protein hydrolysates have demonstrated moderate ice recrystallization inhibition (IRI) activity, but the properties of the unhydrolyzed protein contributing to this activity are not well known. The objective of this research was to identify the main protein processing factors important to the varying IRI activities observed. Three possible modification reactions were applied to soy protein isolate (SPI): the Maillard reaction that can occur in soy flour before protein isolation, heat denaturation of the fully defatted protein, and heat denaturation of the protein with the presence of residual lipid, mainly polar phospholipids. These modified proteins were hydrolyzed by Alcalase protease (for 2 min) to produce hydrolysates, which were characterized by HPLC and FTIR to investigate how molecular weight (MW) and changes in secondary structure relate to IRI activity. A multilinear regression with the parameters of modification type, surface hydrophobicity, secondary structure profile, and average MW of the hydrolysates was used to investigate their roles in reducing ice crystal size. It was discovered that polar lipids present in the soy hydrolysate samples and MW were the only significant factors (p < 0.05) for IRI activity of SPI hydrolysates which had an ice crystal size reduction from 22.0% to 36.7%. This study demonstrates for the first time a protein hydrolysate‐phospholipid interaction can produce IRI active molecules. 
    more » « less
  2. ; ; ; ; (, Journal of Insects as Food and Feed)
    Abstract Black soldier fly larvae (BSFL) have demonstrated cold tolerance that suggests the presence of cryoprotective molecules. The objective of this research was to investigate if the proteins present in the BSFL have ice recrystallization inhibition (IRI) activity and how different environmental factors affect the activity. Osborne fractionation of the defatted BSFL was performed to separate the proteins based on solubility, then preparative size exclusion chromatography was used to fractionate the albumin fraction by molecular size to isolate IRI or ice binding proteins. The major proteins in the active fractions were identified by mass spectrometry, and molecular dynamic simulations were performed with two proteins identified to investigate their behaviors in an ice-water system. The main finding is the strong IRI activity of the water-soluble BSFL albumin fraction and the column fractionated fraction 1. This fraction had a 40.4-79.9% reduction in ice crystal size at 1% concentration and under a wide pH (3-9) and salt (10-200 mM NaCl) concentration. Pure proteins recovered were sequenced and identified as cuticle proteins by mass spectrometry. One cuticle protein demonstrated strong H-bonding and structural flexibility by molecular dynamic simulations, explaining the IRI and ice binding activity. This is the first time BSFL protein is reported to possess IRI activity, and such protein extract can be feasibly obtained compared to other naturally occurring antifreezing proteins. 
    more » « less
  3. ; ; ; ; ; ; ; ; (, Proceedings of the National Academy of Sciences)
    Biological ice nucleation plays a key role in the survival of cold-adapted organisms. Several species of bacteria, fungi, and insects produce ice nucleators (INs) that enable ice formation at temperatures above −10 °C. Bacteria and fungi produce particularly potent INs that can promote water crystallization above −5 °C. Bacterial INs consist of extended protein units that aggregate to achieve superior functionality. Despite decades of research, the nature and identity of fungal INs remain elusive. Here, we combine ice nucleation measurements, physicochemical characterization, numerical modeling, and nucleation theory to shed light on the size and nature of the INs from the fungusFusarium acuminatum. We find ice-binding and ice-shaping activity ofFusariumIN, suggesting a potential connection between ice growth promotion and inhibition. We demonstrate that fungal INs are composed of small 5.3 kDa protein subunits that assemble into ice-nucleating complexes that can contain more than 100 subunits.FusariumINs retain high ice-nucleation activity even when only the ~12 kDa fraction of size-excluded proteins are initially present, suggesting robust pathways for their functional aggregation in cell-free aqueous environments. We conclude that the use of small proteins to build large assemblies is a common strategy among organisms to create potent biological INs. 
    more » « less
  4. ; ; ; ; ; (, Canadian Journal of Forest Research)
    We evaluated shoot nonstructural carbohydrate (NSC) concentrations, stem wound closure, and radial growth of sugar maple ( Acer saccharum Marsh.) and red maple ( Acer rubrum L.) trees in a novel ice storm experiment in which five storm treatments (0, 6.4, 12.7, and 19.1 mm of radial ice accretion in 1 year and 12.7 mm of ice in two consecutive years) were applied within a mature northern hardwood forest. We tested for changes in physiology at two levels: (1) associated with plot-level ice treatments and (2) with crown damage classes of individual trees. Few differences in NSC or wound closure associated with treatment were found. Growth decreased for red maple in the medium and high treatments and sugar maple in the high treatment but no other treatments. Changes in physiology were more evident when assessed using crown damage classes. Two NSC components were elevated in sugar and red maples with high (≥50%) crown damage. Wound closure was less for red maples with high damage, and separation among damage classes was even greater for sugar maple. Red maples with moderate (<50%) and high crown damage showed gradually declining growth, whereas sugar maples with high damage showed ∼80% reduction in growth the first year after injury. 
    more » « less
  5. ; ; (, Journal of Geophysical Research: Atmospheres)
    Abstract Arctic single‐layer mixed‐phase clouds were studied using a one‐dimensional model that incorporated the adaptive habit growth model for ice microphysics. The base case was from the Indirect and Semidirect Aerosol Campaign, and it was perturbed over a range of cloud‐average temperatures, maximum (per model run) ice nuclei (IN) concentrations, and large‐scale subsidence velocities. For each parameter combination, the model was iterated out to 48 hr, and the time, called the glaciation time, to complete disappearance of liquid recorded if this occurred within the 48 hr. Dependence of glaciation times on cloud‐average temperatures from −30°C to −5°C, maximum IN concentrations from 0.10 to 30 L−1, and strong–no subsidence, with both isometric and habit‐dependent ice crystal growth, were investigated. For isometric crystal growth, the relationship between the critical maximum IN concentration (INcrit), the maximum (per model run) IN concentration above which a mixed‐phase cloud glaciated within a fixed model runtime, and cloud‐average temperature was monotonic. INcritdecreased with decreasing cloud‐average temperature. Strengthening of subsidence led to a further decrease in INcritfor every cloud‐average temperature. For habit‐dependent ice crystal growth, the relationship between INcritand cloud‐average temperature was nonmonotonic. Ice crystals develop dendritic and columnar habits near −15°C and −7°C, respectively, and at these two temperatures, ice crystals grew and depleted supercooled liquid water faster than the case when ice crystals grew isometrically. This led to deep local minima in INcritaround these two temperatures in the model runs. Habit‐dependent ice crystal growth, coupled with changes in cloud‐average temperature, INcrit, and subsidence strength, led to significant changes in Arctic single‐layer mixed‐phase cloud lifetimes. 
    more » « less
  • Citation Formats
  • MLA
  • APA
  • Chicago
  • BibTeX
  • Save / Share this Record
  • Send to Email