CRYSTAL STRUCTURE OF TbIG IN VARIATION OF TEMPERATURE (298, 150 K) AND MAGNETIC FIELD (H=0, 0.1 T)

Konno, Masae; Mikami-Kido, Mami

doi:10.1246/cl.1984.21

Cited by 5 publications

(6 citation statements)

References 8 publications

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“…For these highly magnetized neutron stars, the distortion induced by the magnetic torque becomes significant, strongly enhancing the GW emission. In the case of a pure poloidal internal magnetic field matching to the dipolar field B in the exterior, the ellipticity is given by (Bonazzola & Gourgoulhon 1996;Konno et al 2000):…”

Section: Rotating Neutron Stars: Tri-axial Emissionmentioning

confidence: 99%

The astrophysical gravitational wave stochastic background

Regimbau

2011

Res. Astron. Astrophys.

260

306

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A gravitational wave stochastic background of astrophysical origin may have resulted from the superposition of a large number of unresolved sources since the beginning of stellar activity. Its detection would put very strong constrains on the physical properties of compact objects, the initial mass function or the star formation history. On the other hand, it could be a 'noise' that would mask the stochastic background of cosmological origin. We review the main astrophysical processes able to produce a stochastic background and discuss how it may differ from the primordial contribution by its statistical properties. Current detection methods are also presented.

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Section: Rotating Neutron Stars: Tri-axial Emissionmentioning

confidence: 99%

The astrophysical gravitational wave stochastic background

Regimbau

2011

Res. Astron. Astrophys.

260

306

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“…In particular, the native enzyme contains a fairly high content of a-helical structure (40%). However, it should be mentioned that quantitative estimates of secondary structure from CD spectra suffer from several theoretical (35-38) and experimental (39,40) limitations, so that the quantitative reliability of the figures reported in Table 1 can be questioned. This is particularly true for 0and unordered structure, whereas the amount of a-helix generally appears more reliable (cf.…”

Section: Properties Of Native Arginasementioning

confidence: 99%

Spectroscopic study on the structure and stability of beef liver arginase

Rossi

Grandi

Dalzoppo

et al. 1983

International Journal of Peptide and Protein Research

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The secondary and tertiary structure of the oligomeric arginase (EC 3.5.3.1) from beef liver was investigated by circular dichroism (CD) and fluorescence measurements. The far‐ultraviolet CD spectrum of the enzyme at neutral pH is indicative of high helical content. The intrinsic fluorescence emission of the protein is due to tryptophan, the contribution of tyrsoine being small. Upon excitation at 295 nm, the maximum of emission occurs at 330 nm, implying that the trytophan residues are rather buried in a hydrophobic interior of the protein. Ethylenediaminetetraacetic acid (EDTA), which inactivates the enzyme by removing the functional Mn2+‐ion from the enzyme, does not dissociate the enzyme into subunits, nor affect noticeably its secondary and tertiary structure. Inactivation occurs in the acid pH range, being complete at pH below 4. However, acidification up to pH 1.5 produced only limited changes in the far‐ultraviolet CD spectrum and intrinsic fluorescence emission properties. The enzyme shows noteworthy thermal stability, as shown by measuring the residual activity after heating and by evaluating the temperature dependence of the CD signal at 220 nm and the intensity of emission fluorescence. A temperature of half inactivation (Tm) of 77° was determined upon heating the enzyme at pH 7.5 in the presence of Mn2+‐ions for 10 min; in the presence of EDTA, Tm is shifted to 55°. Taken together, these observations indicate that the structural stability of beef liver arginase arises from a clustering of hydrophobic amino acids and from Mn2+‐ion binding.

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“…This affiliation is in spite of the distant relationship between red algae and diatoms. Examination of hypothetical homologs from the acromelic acid producing mushroom may enable better insight into how these enzymes evolved (44). In addition, the detailed understanding of DabA described here may help inform the creation of PCR based assays that can detect DabA expression in the environment and serve as an early warning system before domoic acid accumulates to toxic levels.…”

Section: Resultsmentioning

confidence: 99%

Algal Neurotoxin Biosynthesis Repurposes the Terpene Cyclase Structural Fold Into anN-prenyltransferase

Chekan

McKinnie

Noel

et al. 2020

Preprint

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Prenylation is a common biological reaction in all domains of life whereupon prenyl diphosphate donors transfer prenyl groups onto small molecules as well as large proteins. The enzymes that catalyze these biotransformations are structurally distinct from ubiquitous terpene cyclases that instead assemble terpene molecules via intramolecular rearrangements. Herein we report the structure and molecular details of a new family of prenyltransferases from marine algae that repurposes the terpene cyclase structural fold for the Nprenylation of glutamic acid during the biosynthesis of the potent neurochemicals domoic acid and kainic acid. We solved the X-ray crystal structure of the prenyltransferase found in domoic acid biosynthesis, DabA, and show distinct active site binding modifications that remodel the canonical Mg 2+ -binding motif. We then applied our structural knowledge of DabA and a homologous enzyme from the kainic acid biosynthetic pathway, KabA, to alter their isoprene donor specificities (geranyl versus dimethylallyl diphosphate) by a single amino acid switch. While the diatom DabA and seaweed KabA enzymes share a common evolutionary lineage, they are distinct from all other terpene cyclases, suggesting a very distant ancestor. SignificanceDomoic acid is a neurotoxin produced by marine algae that readily bioaccumulates in shellfish and significantly impacts both human and animal life. The first committed step of the biosynthesis of domoic acid is the Nprenylation of L-glutamic acid by the enzyme DabA. By solving the crystal structure of DabA, we demonstrate that this enzyme has repurposed the common terpene cyclase fold to catalyze an extremely unusual reaction, N-prenylation of an unactivated primary amine. Application of these structural insights enabled rational engineering of two N-prenyltransferase enzymes to accept alternative prenyl donors. Ultimately, these results not only expand the scope of reactions catalyzed by a terpene cyclase family member, but will help inform future domoic acid environmental monitoring efforts.

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CRYSTAL STRUCTURE OF TbIG IN VARIATION OF TEMPERATURE (298, 150 K) AND MAGNETIC FIELD (H=0, 0.1 T)

Cited by 5 publications

References 8 publications

The astrophysical gravitational wave stochastic background

The astrophysical gravitational wave stochastic background

Spectroscopic study on the structure and stability of beef liver arginase

Algal Neurotoxin Biosynthesis Repurposes the Terpene Cyclase Structural Fold Into anN-prenyltransferase

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