7 research outputs found
Demonstration for a two-axis interferometric tilt sensor in KAGRA
Recently, a folded Mach–Zehnder interferometer with homodyne in- and quadrature-phase detection was proposed as a high-precision, wide-dynamic range tilt sensor. By way of a practical application and to validate actual performance, two-axis tilt sensors were developed and installed for one mirror of the input mode cleaner cavity in KAGRA, the large-scale cryogenic gravitational-wave telescope in Kamioka, Gifu, Japan. Building on previous work, we have demonstrated that the two-axis tilt sensor has properly sensed the tilt angle changes of the mirror motion with high precision and without calibration. Compared with our initial angular sensor, an optical lever, which is calibrated by using the interferometer tilt sensor, we found that both sensors showed actual tilt motions of the mirror at low frequencies, and the two-axis interferometer sensor has a better sensitivity at higher frequencies
Demonstration for a two-axis interferometric tilt sensor in KAGRA
Recently, a folded Mach–Zehnder interferometer with homodyne in- and quadrature-phase detection was proposed as a high-precision, wide-dynamic range tilt sensor. By way of a practical application and to validate actual performance, two-axis tilt sensors were developed and installed for one mirror of the input mode cleaner cavity in KAGRA, the large-scale cryogenic gravitational-wave telescope in Kamioka, Gifu, Japan. Building on previous work, we have demonstrated that the two-axis tilt sensor has properly sensed the tilt angle changes of the mirror motion with high precision and without calibration. Compared with our initial angular sensor, an optical lever, which is calibrated by using the interferometer tilt sensor, we found that both sensors showed actual tilt motions of the mirror at low frequencies, and the two-axis interferometer sensor has a better sensitivity at higher frequencies
Seven Cysteine-Deficient Mutants Depict the Interplay between Thermal and Chemical Stabilities of Individual Cysteine Residues in Mitogen-Activated Protein Kinase c‑Jun N‑Terminal Kinase 1
Intracellular proteins can have free cysteines that may
contribute to their structure, function, and stability; however, free
cysteines can lead to chemical instabilities in solution because of
oxidation-driven aggregation. The MAP kinase, c-Jun N-terminal kinase
1 (JNK1), possesses seven free cysteines and is an important drug
target for autoimmune diseases, cancers, and apoptosis-related diseases.
To characterize the role of cysteine residues in the structure, function,
and stability of JNK1, we prepared and evaluated wild-type JNK1 and
seven cysteine-deficient JNK1 proteins. The nonreduced sodium dodecyl
sulfate–polyacrylamide gel electrophoresis experiments showed
that the chemical stability of JNK1 increased as the number of cysteines
decreased. The contribution of each cysteine residue to biological
function and thermal stability was highly susceptible to the environment
surrounding the particular cysteine mutation. The mutations of solvent-exposed
cysteine to serine did not influence biological function and increased
the thermal stability. The mutation of the accessible cysteine involved
in the hydrophobic pocket did not affect biological function, although
a moderate thermal destabilization was observed. Cysteines in the
loosely
assembled hydrophobic environment moderately contributed to thermal
stability, and the mutations of these cysteines had a negligible effect
on enzyme activity. The other cysteines are involved in the tightly
filled hydrophobic core, and mutation of these residues was found
to correlate with thermal stability and enzyme activity. These findings
about the role of cysteine residues should allow us to obtain a stable
JNK1 and thus promote the discovery of potent JNK1 inhibitors