7 research outputs found
Two-Molecule Force Spectroscopy on Proteins
Many elastomeric proteins, which
play important roles
in a wide
range of biological processes, exist as parallel/antiparallelly arranged
dimers or multimers to perform their mechanobiological functions.
For example, in striated muscle sarcomeres, the giant muscle protein
titin exists as hexameric bundles to mediate the passive elasticity
of muscles. However, it has not been possible to directly probe the
mechanical properties of such parallelly arranged elastomeric proteins.
And it remains unknown if the knowledge obtained from single-molecule
force spectroscopy studies can be directly extrapolated to such parallelly/antiparallelly
arranged systems. Here, we report the development of atomic force
microscopy (AFM)-based two-molecule force spectroscopy to directly
probe the mechanical properties of two elastomeric proteins that are
arranged in parallel. We developed a twin-molecule approach to allow
two parallelly arranged elastomeric proteins to be picked up and stretched
simultaneously in an AFM experiment. Our results clearly revealed
the mechanical features of such parallelly arranged elastomeric proteins
during force–extension measurements and allowed for the determination
of mechanical unfolding forces of proteins in such an experimental
setting. Our study provides a general and robust experimental strategy
to closely mimic the physiological condition of such parallel elastomeric
protein multimers
Bis(boryl anion)-Substituted Pyrenes: Syntheses, Characterizations, and Crystal Structures
The two new diboranes <b>1</b> and <b>2</b> connected by a pyrene moiety at the 1,6- and
1,3-positions, respectively, were synthesized, and their two-electron-reduction
reactions were investigated. The doubly reduced species <b>1</b><sup>••2–</sup> is silent in electron paramagnetic
resonance (EPR) and nuclear magnetic resonance (NMR) spectroscopic
measurements, suggesting a quasi-quinoidal structure with a diradical
character of <b>1</b><sup>••2–</sup>, which
has a singlet–triplet gap of 6.6 kcal mol<sup>–1</sup> as determined by theoretical calculations. In contrast, the reduction
product <b>2</b><sup>••2–</sup> is EPR
active and theoretical calculations indicate that <b>2</b><sup>••2–</sup> has an open-shell singlet ground
state with a singlet–triplet energy gap of 4.9 kcal mol<sup>–1</sup>
JTXK granule decreased the plasma insulin concentration, and improved insulin sensitivity in T2DM KKAy mice.
<p>(A) Serum insulin concentration was reduced by JTXK granule at the end of the treatment. (B) Serum fasting glucose levels of the mice in each group. (C) HOMA-IR of the mice in each group. (D) ISI of the mice in each group. Data are expressed as the mean ± SE. *P<0.05, **P<0.01 vs. control group (T2DM KKAy mice). ## P<0.01 vs. non-diabetic control group (C57BL/6J mice). HOMA-IR = FBG (mmol/l)×FINS (μU/ml)/22.5; ISI = 1/[FBG (mmol/l)×FINS (μU/ml)].</p
JTXK granule altered mRNA expression in the PI3K/Akt signalling pathway in skeletal muscle.
<p>IRS-1, insulin receptor substrate-1; PI3K, phosphatidylinositol 3-kinase; Akt, serine/threonine-protein kinase; p-Akt, phosphorylated Akt; Glut4, glucose transporter 4; GSK3β, Glycogen synthase kinase 3 β. Data are expressed as the mean ± SE of six mice in each group. *P<0.05, **P<0.01 vs. control group (T2DM KKAy mice).</p
JTXK granule improved results of oral glucose tolerance test (OGTT) in T2DM KKAy mice.
<p>A and C showed results of OGTT in each group at the fifth and the tenth week. B and D showed area under the curve (AUC) of the OGTT among groups at the fifth and the tenth weeks. Data are expressed as the mean ± SE of ten mice in each group. *P<0.05, **P<0.01 vs. control group (T2DM KKAy mice). ## P<0.01 vs. non-diabetic control group (C57BL/6J mice).</p
JTXK granule decreased the plasma insulin concentration, and improved insulin sensitivity in T2DM KKAy mice.
<p>(A) Serum insulin concentration was reduced by JTXK granule at the end of the treatment. (B) Serum fasting glucose levels of the mice in each group. (C) HOMA-IR of the mice in each group. (D) ISI of the mice in each group. Data are expressed as the mean ± SE. *P<0.05, **P<0.01 vs. control group (T2DM KKAy mice). ## P<0.01 vs. non-diabetic control group (C57BL/6J mice). HOMA-IR = FBG (mmol/l)×FINS (μU/ml)/22.5; ISI = 1/[FBG (mmol/l)×FINS (μU/ml)].</p
JTXK granule influenced relevant protein expression in the PI3K/Akt signalling pathway in skeletal muscle.
<p>IRS-1, insulin receptor substrate-1; PI3K, phosphatidylinositol 3-kinase; Akt, serine/threonine-protein kinase; p-Akt, phosphorylated Akt; Glut4, glucose transporter 4; GSK3β, Glycogen synthase kinase 3β. Data are expressed as the mean ± SE of six mice in each group. *P<0.05, **P<0.01 vs. control group (T2DM KKAy mice). ## P<0.01 vs. non-diabetic control group (C57BL/6J mice).</p