Expanding the Scope of Cross-Link Identifications by Incorporating Collisional Activated Dissociation and Ultraviolet Photodissociation Methods.

With the advent of new cross-linking chemistries, analytical technologies, and search algorithms, cross-linking has become an increasingly popular strategy for evaluating tertiary and quaternary structures of proteins. Collisional activated dissociation remains the primary MS/MS method for identifications of peptide cross-links in high throughput workflows. Ultraviolet photodissociation (UVPD) at 193 nm has emerged as an alternative ion activation method well-suited for characterization of peptides and has been found in some cases to identify different peptides or provide distinctive sequence information than obtained by collisional activation methods. Complementary high energy collision dissociation (HCD) and UVPD were used in the present study to characterize protein cross-linking for bovine serum albumin, hemoglobin, and E. coli ribosome. Cross-links identified by HCD and UVPD using bis(sulfosuccinimidyl)suberate (BS3), a homobifunctional amine-to-amine cross-linker, and 4-(4,6-dimethoxy-1,3,5-triazin-2-yl)-4-methylmorpholinium chloride (DMTMM), a heterofunctional amine-to-carboxylic acid cross-linker, were evaluated in the present study. While more unique BS3 cross-links were identified by HCD, UVPD, and HCD provided a complementary panel of DMTMM cross-links which extended the degree of structural insight obtained for the proteins.

Epsilon Aminocaproic Acid's Safety and Efficacy in Pediatric Surgeries Including Craniosynostosis Repair: A Review of the Literature.

Craniosynostosis, the premature fusion of skull sutures in children, requires surgical correction. This procedure routinely requires allogeneic blood transfusions, which are associated with multiple risks of their own. Since 2008, antifibrinolytics tranexamic acid (TXA) and epsilon aminocaproic acid (EACA or Amicar) have been widely used. There is literature comparing the two agents in scoliosis and cardiothoracic surgery, but the literature comparing the two agents in pediatric craniofacial surgery (CF) is limited. Tranexamic acid use is more common in pediatric CF surgery and has been thoroughly studied; however, it costs about three times as much as EACA and has been associated with seizures. This study compiles the literature assessing the safety and efficacy of EACA in reducing blood loss and transfusion volumes in children and explores its potential use in pediatric CF surgery. Papers from 2000 to 2021 regarding the effectiveness and safety of EACA in Pediatric scoliosis, cardiothoracic, and craniosynostosis surgery were reviewed and compiled. Papers were found via searching PubMed and Cochrane databases with the key terms: Epsilon aminocaproic acid, EACA, Amicar, Tranexamic acid, TXA, craniosynostosis, scoliosis, cardiothoracic, and pediatric. Prospective studies, retrospective studies, and meta-analyses were included. Twenty-nine papers were identified as pertinent from the literature searched. Four were meta-analyses, 14 were retrospective, and 11 were prospective. Of these papers, seven were of cardiac surgery, 12 were of scoliosis, and nine were of craniosynostosis. During our search, EACA has been shown to consistently reduce blood transfusion volumes compared to control. However, it is not as effective when compared to TXA. EACA has a similar safety profile to TXA but has a reduced risk of seizures. There are not many studies of EACA in craniosynostosis repair, but the existing literature shows promising results for EACA's efficacy and safety, warranting more studies.

Peptide Sequence Influence on the Conformational Dynamics and DNA binding of the Intrinsically Disordered AT-Hook 3 Peptide.

The intrinsically disordered ATHP3 was studied at native conditions and in complex with DNA using single amino acid substitutions and high-resolution ion mobility spectrometry coupled to mass spectrometry (trapped IMS-MS). Results showed that ATHP3 can exist in multiple conformations at native conditions (at least 10 conformers were separated), with a variety of proline cis/trans orientations, side chain orientations and protonation sites. When in complex with AT rich DNA hairpins, the -RGRP- core is essential for stabilizing the ATHP3: DNA complex. In particular, the arginine in the sixth position plays an important role during binding to AT-rich regions of hairpin DNA, in good agreement with previous NMR and X-ray data. Mobility based correlation matrices are proposed as a way to reveal differences in structural motifs across the peptide mutants based on the conformational space and relative conformer abundance.