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Imaging of Hypoxia, Apoptosis, and Inflammation
Published in George C. Kagadis, Nancy L. Ford, Dimitrios N. Karnabatidis, George K. Loudos, Handbook of Small Animal Imaging, 2018
Stavros Spiliopoulos, Athanasios Diamantopoulos
Other agents developed to recognize membrane-bound phosphatidylserine for the detection of apoptotic cells include zinc-dipicolylamine coordination complex, cationic liposomes, 12-resi-due phosphatidylserine-binding peptide, and C2A domain of synaptotagmin I (Bose et al. 2004; Hanshaw et al. 2005; Shao et al. 2007). Of interest, the latter develops a calcium-dependent bond with the negatively charged membrane phospholipids such as phosphatidylserine and, therefore, C2A and its mutants can be used for both SPECT and MRI imaging (99mTc labeling of a fusion protein for SPECT and with superparamagnetic iron oxide particles and Gd3+ for MRI imaging) (Jung et al. 2004; Zhao et al. 2006; Krishnan et al. 2008; Thapa et al. 2008). C2A complexes demonstrated significantly higher disassociation constant compared with different types of annexin V (Alam et al. 2010). Finally, the results using novel molecular imaging probes such as ApoPep-1 (apoptosis-targeting peptide-1), which targeted apoptotic cells in tumor tissue using fluorescent in vivo imaging by binding to the 1H histone exposed on the apoptotic cells’ surface, have been recently reported. The authors concluded that ApoPep-1 holds great promise as a in vivo apoptosis imaging probe and that histone H1 constitutes a unique molecular signature for apoptotic imaging (Figure 31.1) (Wang et al. 2010).
General Introductory Topics
Published in Vadim Backman, Adam Wax, Hao F. Zhang, A Laboratory Manual in Biophotonics, 2018
Vadim Backman, Adam Wax, Hao F. Zhang
Second, arrays of nucleosomes wrap into a 30-nm chromatin fiber, it is believed with the help of histone H1 (although the role of histone H1 has recently been brought into question), and these 30-nm fibers pack into the higher-order chromatin structure. In the latter process, scaffolding nuclear proteins are important. The higher-order chromatin structure has several levels of organization, which are an active topic of current research. The 30-nm chromatin fiber is believed to be a dynamic structure that readily unfolds into a 10-nm beads-on-a-string fiber ready for transcription. However, some recent studies question the existence of the 30-nm chromatin fiber, suggesting that it might be an artifact of chromatin preparation as opposed to a native structure that exists in vivo in live cells. As with other levels of chromatin organization, we have to wait until new research leads to a consensus.
Thioredoxin-Based Peptide Aptamers: Development and Applications
Published in Rakesh N. Veedu, Aptamers, 2017
David S. Burz, Sergey Reverdatto, Alexander Shekhtman
The earliest study employed Y2H selection to isolate PAs against human cyclin-dependent kinase 2 (Cdk2) from a combinatorial library of 2.9 × 109 molecules containing 20-amino-acid-residue peptide inserts constrained within the TrxA active site loop [3]. The 20-repeat sequence, NNG/T, contained a G or a T at the third position of the codon to reduce the frequency of stop codons, while maintaining the maximum diversity of amino acids. Fourteen PAs were isolated, and six were characterized in vitro and found to have nanomolar binding affinity for Cdk2 and to inhibit phosphorylation of histone H1 by Cdk2/cyclin E kinase, most likely by competing with its H1 substrate.
Direct and cost-effective method for histone isolation from cultured mammalian cells
Published in Preparative Biochemistry & Biotechnology, 2023
Anja Batel, Mirjana Polović, Mateo Glumac, Andrea Gelemanović, Matilda Šprung, Ivana Marinović Terzić
Two copies of each canonical histone[4] form the nucleosome core particle. In some cases, specialized histone variants substitute for the core canonical histones. Canonical histones are generated during DNA replication, whereas histone variants assemble independently of replication.[5] Histones H2B and H4 have fewer variants than histones H2A and H3.[6] Histone variants appear to have different roles in chromatin: they change the native physical properties of nucleosomes, assist in the formation of chromatin-associated complexes, and carry different or unique post-translational modifications.[7] Linker histone H1 is responsible for keeping the electrostatic charge stable and maintaining regular spacing between adjacent nucleosomes. It is rapidly exchanged on euchromatin in mammalian cells, approximately every 4 min, as opposed to core histones which showed no exchange over the comparable period.[8]