TY  - JOUR
A1  - Abbas, Ioana M.
A1  - Vranic, Marija
A1  - Hoffmann, Holger
A1  - El-Khatib, Ahmed H.
A1  - Montes-Bayón, María
A1  - Möller, Heiko Michael
A1  - Weller, Michael G.
T1  - Investigations of the Copper Peptide Hepcidin-25 by
LC-MS/MS and NMR⁺
JF  - International Journal of Molecular Sciences
N2  - Hepcidin-25 was identified as themain iron regulator in the human body, and it by binds to the sole iron-exporter ferroportin. Studies showed that the N-terminus of hepcidin is responsible for this interaction, the same N-terminus that encompasses a small copper(II) binding site known as the ATCUN (amino-terminal Cu(II)- and Ni(II)-binding) motif. Interestingly, this copper-binding property is largely ignored in most papers dealing with hepcidin-25. In this context, detailed investigations of the complex formed between hepcidin-25 and copper could reveal insight into its biological role. The present work focuses on metal-bound hepcidin-25 that can be considered the biologically active form. The first part is devoted to the reversed-phase chromatographic separation of copper-bound and copper-free hepcidin-25 achieved by applying basic mobile phases containing 0.1% ammonia. Further, mass spectrometry (tandemmass spectrometry (MS/MS), high-resolutionmass spectrometry (HRMS)) and nuclear magnetic resonance (NMR) spectroscopy were employed to characterize the copper-peptide. Lastly, a three-dimensional (3D)model of hepcidin-25with bound copper(II) is presented. The identification of metal complexes and potential isoforms and isomers, from which the latter usually are left undetected by mass spectrometry, led to the conclusion that complementary analytical methods are needed to characterize a peptide calibrant or referencematerial comprehensively. Quantitative nuclear magnetic resonance (qNMR), inductively-coupled plasma mass spectrometry (ICP-MS), ion-mobility spectrometry (IMS) and chiral amino acid analysis (AAA) should be considered among others.
KW  - hepcidin-25
KW  - copper
KW  - nickel
KW  - copper complex
KW  - ATCUN motif
KW  - metal complex
KW  - MS
KW  - NMR structure
KW  - metal peptide
KW  - metalloprotein
KW  - metallopeptide
KW  - isomerization
KW  - racemization
KW  - purity
KW  - reference material
Y1  - 2018
U6  - https://doi.org/10.3390/ijms19082271
SN  - 1422-0067
SN  - 1661-6596
VL  - 19
IS  - 8
PB  - Molecular Diversity Preservation International
CY  - Basel
ER  - 
TY  - JOUR
A1  - Hsu, Hsiang-Wen
A1  - Schmidt, Jürgen
A1  - Kempf, Sascha
A1  - Postberg, Frank
A1  - Moragas-Klostermeyer, Georg
A1  - Seiss, Martin
A1  - Hoffmann, Holger
A1  - Burton, Marcia
A1  - Ye, ShengYi
A1  - Kurth, William S.
A1  - Horanyi, Mihaly
A1  - Khawaja, Nozair
A1  - Spahn, Frank
A1  - Schirdewahn, Daniel
A1  - Moore, Luke
A1  - Cuzzi, Jeff
A1  - Jones, Geraint H.
A1  - Srama, Ralf
T1  - In situ collection of dust grains falling from Saturn’s rings into its atmosphere
JF  - Science
N2  - Saturn’s main rings are composed of >95% water ice, and the nature of the remaining few percent has remained unclear. The Cassini spacecraft’s traversals between Saturn and its innermost D ring allowed its cosmic dust analyzer (CDA) to collect material released from the main rings and to characterize the ring material infall into Saturn. We report the direct in situ detection of material from Saturn’s dense rings by the CDA impact mass spectrometer. Most detected grains are a few tens of nanometers in size and dynamically associated with the previously inferred “ring rain.” Silicate and water-ice grains were identified, in proportions that vary with latitude. Silicate grains constitute up to 30% of infalling grains, a higher percentage than the bulk silicate content of the rings.
Y1  - 2018
U6  - https://doi.org/10.1126/science.aat3185
SN  - 0036-8075
SN  - 1095-9203
VL  - 362
IS  - 6410
SP  - 49
EP  - +
PB  - American Assoc. for the Advancement of Science
CY  - Washington
ER  -