6 research outputs found
Toward a Structure Determination Method for Biomineral-Associated Protein Using Combined Solid- State NMR and Computational Structure Prediction
SummaryProtein-biomineral interactions are paramount to materials production in biology, including the mineral phase of hard tissue. Unfortunately, the structure of biomineral-associated proteins cannot be determined by X-ray crystallography or solution nuclear magnetic resonance (NMR). Here we report a method for determining the structure of biomineral-associated proteins. The method combines solid-state NMR (ssNMR) and ssNMR-biased computational structure prediction. In addition, the algorithm is able to identify lattice geometries most compatible with ssNMR constraints, representing a quantitative, novel method for investigating crystal-face binding specificity. We use this method to determine most of the structure of human salivary statherin interacting with the mineral phase of tooth enamel. Computation and experiment converge on an ensemble of related structures and identify preferential binding at three crystal surfaces. The work represents a significant advance toward determining structure of biomineral-adsorbed protein using experimentally biased structure prediction. This method is generally applicable to proteins that can be chemically synthesized
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Is Exercise Extra? A Mixed Methods Examination of Cultural Barriers and Enablers of Physical Activity in Management of Type 2 Diabetes in M’Bour, Senegal
Objective:
This study seeks to produce culturally-attuned recommendations for disease management in individuals with type 2 diabetes in M’Bour, Senegal.
Methods:
The PEN-3 Cultural Model (PEN-3) framed this mixed methods study to capture a) the qualitative barriers and enablers to participating in physical activity through narrative interviews; as well as b) the quantitative extent to which participants engaged in physical activity through the International Physical Activity Questionnaire (IPAQ). Content analysis identified emergent themes from interviews and descriptive statistics summarized IPAQ responses.
Results:
Among 41 individuals formally diagnosed with diabetes, the mean age was 58 (SD=11.8). Results elicited from PEN-3 included several barriers and enablers to physical activity. Barriers included prohibitive costs of gym membership and exercise equipment; limb pain; and feeling ill. Participants reported walking as their main source of exercise, with an average frequency of 4 days per week (SD=2.8). Although patients reported a lack of others with whom to exercise, familial support aided in maintaining exercise behaviors such as walking.
Conclusions:
Given participants’ need for exercise companions, group-based activities ​may be useful. Patients with diabetes may also benefit from complimentary home-based exercises that are gentle and pain alleviating
A REDOR ssNMR Investigation of the Role of an N‑Terminus Lysine in R5 Silica Recognition
Diatoms
are unicellular algae that construct cell walls called frustules by
the precipitation of silica, using special proteins that order the
silica into a wide variety of nanostructures. The diatom species <i>Cylindrotheca fusiformis</i> contains proteins called silaffins
within its frustules, which are believed to assemble into supramolecular
matrices that serve as both accelerators and templates for silica
deposition. Studying the properties of these biosilicification proteins
has allowed the design of new protein and peptide systems that generate
customizable silica nanostructures, with potential generalization
to other mineral systems. It is essential to understand the mechanisms
of aggregation of the protein and its coprecipitation with silica.
We continue previous investigations into the peptide R5, derived from
silaffin protein sil1p, shown to independently catalyze the precipitation
of silica nanospheres in vitro. We used the solid-state NMR technique <sup>13</sup>CÂ{<sup>29</sup>Si} and <sup>15</sup>NÂ{<sup>29</sup>Si} REDOR
to investigate the structure and interactions of R5 in complex with
coprecipitated silica. These experiments are sensitive to the strength
of magnetic dipole–dipole interactions between the <sup>13</sup>C nuclei in R5 and the <sup>29</sup>Si nuclei in the silica and thus
yield distance between parts of R5 and <sup>29</sup>Si in silica.
Our data show strong interactions and short internuclear distances
of 3.74 ± 0.20 Å between <sup>13</sup>CO Lys3 and
silica. On the other hand, the C<sub>α</sub> and C<sub>β</sub> nuclei show little or no interaction with <sup>29</sup>Si. This
selective proximity between the K3 Cî—»O and the silica supports
a previously proposed mechanism of rapid silicification of the antimicrobial
peptide KSL (KKVVFKVKFK) through an imidate intermediate. This study
reports for the first time a direct interaction between the N-terminus
of R5 and silica, leading us to believe that the N-terminus of R5
is a key component in the molecular recognition process and a major
factor in silica morphogenesis