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"In his thesis, Matthias Junk takes an innovative approach to assess the local structure and dynamics of biological and synthetic amphiphilic macromolecules capable of transporting small molecules. Replacing the latter with stable radicals, he uses state-of-the-art electron paramagnetic resonance (EPR) spectroscopy to describe the highly relevant transport function from the viewpoint of the guest molecules. Such, he demonstrates that the functional structure of human serum albumin in solution significantly differs from its crystal structure, a consequence of the protein’s adaptability to host various endogenous compounds and drug molecules. Further, he shows that the thermal collapse of thermoresponsive hydrogels and dendronized polymers leads to static and dynamic heterogeneities on the nanoscale. These heterogeneities bear consequences for the material’s hosting properties and enable unforeseen complex catalytic functionalities."

"This book about EPR spectroscopy in catalysis, radicals in flavoproteins, weber EPR spectroscopy in polymer science, EPR in protein science, intrinsically disordered proteins, site-directed spin labeling of membrane proteins, structure and dynamics of nucleic acids, and new directions in electron paramagnetic resonance spectroscopy on molecular nanomagnets."

"Human teeth enamel have been irradiated with gamma radiation from Co60 at room temperature and at liquid nitrogen temperature. Paramagnetic centers are formed and have been detected by using electron spin resonance (ESR) spectrometer at room temperature. The main signal is very stable asymmetric singlet, and attributed to h centers in the hydroxyapatite crystals. It is revealed that several factors influence the amplitude of the asymmetric signal. The amplitude and pattern of the asymmetric signal which depend on the orientation of the sample with respect to the magnetic field are analyzed. Based on the properties of the asymmetric signal the difference between the microcrystal arrangement of healthy and diseased teeth are explained."

"Latar belakang: Kami melakukan penelitian selama 10 tahun terakhir untuk mendapatkan gambaran yang komprehensif mengenai kelebihan besi, stres oksidatif, dan kerusakan sel pada pasien talasemia di Jakarta. Metode: Dari sampel darah 15 pasien yang bergantung transfusi (kelompok T), 5 pasien yang belum ditransfusi (kelompok N) dan 10 kontrol (kelompok C) dilakukan analisis plasma dan membran eritrosit yang diisolasi dan strukturnya diteliti dengan spekroskopi electron paramagnetic resonance (EPR) menggunakan doxyl-stearic acid dan maleimido-proxyl spin lable. Data statistik dianalisis dengan ANOVA. Hasil: Terdapat nilai trigliserida lebih tinggi dan nilai kolesterol plasma lebih rendah pada penderita talasemia dibandingkan dengan kontrol. Kadar vitamin E (kelompok C: 21.8 vs T: 6.2 μmol/L) dan reactive thiols (C: 144 vs. T: 61 μmol/L) jauh lebih rendah pada pasien yang bergantung-transfusi. Tanda-tanda stres oksidatif (MDA, C: 1.96 vs. T: 9.2 μmol/L) dan kadar transaminase dalam serum sangat tinggi. Pasien belum ditransfusi memperlihatkan sedikit tanda-tanda terjadinya stres oksidatif, tetapi tidak terdapat tanda-tanda yang berarti adanya kerusakan jaringan atau sel. Parameter membran sel darah merah dari spektroskopi electron paramagnetic resonannce (EPR) menunjukkan hasil yang sangat berbeda-beda untuk setiap kelompok. Pada pasien bergantung-transfusi, struktur membran sel darah merah serta gradien polaritas dan fl uiditas dalam domain lipid menunjukkan rusak; kapasitas mengikat protein tiol di dalam membran lebih rendah dan statis. Kesimpulan: Pada pasien bergantung transfusi, terdapat hubungan antara perubahan pola plasma lipid dan tanda-tanda stres oksidatif dengan kerusakan struktur membran darah merah, yang diukur dengan spektroskopi EPR menggunakan spin-labels lipid dan protein-thiol.

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AbstractBackground: Over the last 10 years, we have investigated thalassemia patients in Jakarta to obtain a comprehensive picture of iron overload, oxidative stress, and cell damage. Methods: In blood samples from 15 transfusion-dependent patients (group T), 5 non-transfused patients (group N) and 10 controls (group C), plasma lipids and lipoproteins, lipid-soluble vitamin E, malondialdehyde (MDA) and thiol status were measured. Isolated eryhtrocyte membranes were investigated with electron paramagnetic resonance (EPR) spectroscopy using doxyl-stearic acid and maleimido-proxyl spin lables. Data were analyzed statistically with ANOVA. Results: Plasma triglycerides were higher and cholesterol levels were lower in thalassemic patients compared to controls. Vitamin E, group C: 21.8 vs T: 6.2 μmol/L) and reactive thiols (C: 144 vs. T: 61 μmol/L) were considerably lower in transfused patients, who exert clear signs of oxidative stress (MDA, C: 1.96 vs T: 9.2 μmol/L) and of tissue cell damage, i.e., high transaminases plasma levels. Non-transfused thalassemia patients have slight signs of oxidative stress, but no signifi cant indication of cell damage. Erythrocyte membrane parameters from EPR spectroscopy differ considerably between all groups. In transfusion-dependent patients the structure of the erythrocyte membrane and the gradients of polarity and fl uidity are destroyed in lipid domains; binding capacity of protein thiols in the membrane is lower and immobilized. Conclusion: In tranfusion-dependent thalassemic patients, plasma lipid pattern and oxidative stress are associated with structural damage of isolated erythrocyte membranes as measured by EPR spectroscopy with lipid and proteinthiol spin labels. "