Expression of Bcl-2 and c-Myc protein seems to be a useful marker to reflect irradiation response and to predict illness condition and patient outcome.
The D-amino acid residues are hallmark building blocks of nonribosomal peptides. Here, we report the bifunctional thioesterase domain (TE domain) Skyxy-TE that catalyzes both epimerization and cyclization in skyllamycin biosynthesis. Skyxy-TE specifically catalyzes the epimerization of the C-terminal L-amino acid residue of the linear substrate, then catalyzes regioselective intramolecular cyclization. The crystal structure of Skyxy-TE was solved at 2.25 Å and site-directed mutagenesis was performed, revealing key residues involved in the epimerization and cyclization. This study expands the understanding of the versatile TE domains and facilitates chemoenzymatic synthesis or combinatorial biosynthesis in the future.
To determine serum levels of soluble intercellular adhesion molecule 1 (sICAM-1) and transforming growth factor ␣ (TGF-␣) in 51 patients with nasopharyngeal carcinoma before, during, and after radiation therapy (5-year follow-up period). Results: The mean±SD serum levels of the 2 cytokines were found to be higher in patients before radiotherapy (sI-CAM-1, 369.6±123.7 ng/mL; TGF-␣, 36.6±24.6 ng/mL) than after radiotherapy (sICAM-1, 225.9±124.3 ng/mL; TGF-␣, 20.2±22.3 ng/mL) (PϽ.05), and they were significantly higher in patients with recurrence (sICAM-1, 512.5±271.2 ng/mL; TGF-␣, 48.2±23.4 ng/mL) and in those who died (sICAM-1, 542.6±245.4 ng/mL; TGF-␣, 50.2±28.8 ng/mL) than in patients with no recurrence (sICAM-1, 217.9 ± 116.4 ng/mL; TGF-d, 21.5 ± 26.8 ng/mL) and in those who survived (sICAM-1, 209.4±167.2 ng/mL; TGF-␣, 20.4 ± 27.3 ng/mL) (PϽ.05). The increases in serum levels occurred approximately 3 months before relapse. Conclusion: We found that sICAM-1 and TGF-␣ levels are extremely useful markers for predicting illness, recurrence, and survival.
Protein glycosylation plays critical roles in many biological processes. However, the fundamental study and application of glycobiology are hindered by the heterogeneousness of oligosaccharides in natural glycoproteins and the difficulty in constructing glycoproteins of human design. Herein, we describe a semisynthetic method to site-specifically modify proteins with reducing carbohydrates. The method involves the genetic incorporation of a side-chain-esterified aspartate, which was subsequently quantitatively converted into alanine-β-hydrazide (Aβz), and chemoselective conjugation of Aβz with a range of readily available reducing carbohydrates. The resulting Aβz-linked GlcNAc is a close mimic of native N-GlcNAc and could be installed on various proteins, including IL-17A and RNase A. Notably, Aβz-linked GlcNAc on proteins reacted with biantennary oligosaccharide oxazoline derivatives through endoglycosidase-catalyzed transglycosylation reactions to enable the assembly of homogeneous glycans on proteins.
Main observation and conclusion
An efficient method for the activation of C‐terminal 4‐mecaptoproline‐ or penicillamine‐containing peptide hydrazides in ligation reactions is reported herein. The corresponding peptide hydrazides can be readily prepared using solid‐phase peptide synthesis, and subsequently activated by acetylacetone (acac) without exogenous thiol additives. Strained peptidyl thiolactones could be the possible reactive intermediates that drastically accelerate the reaction rates at the sterically demanding proline and valine sites. This developed protocol allows for sequential peptide ligations in a one‐pot manner, and expedites the assembly of mucin 1 (MUC‐1) variable number tandem repeat (VNTR) trimers in various glycosylated forms.
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