Development of dual-ligand titanium (IV) hydrophilic network sorbent for highly selective enrichment of phosphopeptides

Biobased Tannic Acid-Chitosan Composite Membranes as Reusable Adsorbents for Effective Enrichment of Phosphopeptides

High-performance reusable materials from renewable resources are rare and urgently required in bioseparation. Herein, a series of tannic acid-chitosan composite membranes for the enrichment of phosphopeptides were fabricated by the freeze casting method. First, a tannic acid-chitosan composite membrane was acquired via the multiple hydrogen bonds between tannic acid and chitosan, which had a long-range aligned three-dimensional microstructure. Second, a covalent-hydrogen bond hybrid composite was also fabricated, with stable and aligned honeycomb-like microstructures that formed by the synergy of covalence and hydrogen bonding. Besides, a ternary composite membrane was "one-pot" synthesized by the copolymerization of tannic acid, chitosan, and Ti4+ ions, indicating the feasibility of involving metal ions in the composition of the polymer skeleton in place of additional modification steps. The as-prepared chitosan composite membranes exhibited excellent performance in the enrichment of phosphopeptides from β-casein tryptic digest and human serum. Benefitting from the long-range aligned honeycomb-like structure coordinated by hydrogen bonds and covalent bonds, and a large number of pyrogallol functional groups provided by tannic acid, the covalent-hydrogen bond hybrid membrane showed excellent reusability and could be reused up to 16 times in phosphopeptide enrichment, as far as we know, which is the best reported result to date.

Recent advances in development of functional magnetic adsorbents for selective separation of proteins/peptides

Nowadays, proteins separation has attracted great attention in proteomics research. Because the proteins separation is helpful for making an early diagnosis of many diseases. Magnetic nanoparticles are an interesting and useful functional material, and have attracted extensive research interest during the past decades. Because of the excellent properties such as easy surface functionalization, tunable biocompatibility, high saturation magnetization etc, magnetic microspheres have been widely used in isolation of proteins/peptides. Notably, with the rapid development of surface decoration strategies, more and more functional magnetic adsorbents have been designed and fabricated to meet the growing demands of biological separation. In this review, we have collected recent information about magnetic adsorbents applications in selective separation of proteins/peptides. Furthermore, we present a comprehensive prospects and challenges in the field of protein separation relying on magnetic nanoparticles.

Advances in proteomics sample preparation and enrichment for phosphorylation and glycosylation analysis

As the common and significant chemical modifications, post-translational modifications (PTMs) play a key role in the functional proteome. Affected by the signal interference, low concentration, and insufficient ionization efficiency of impurities, the direct detection of PTMs by mass spectrometry (MS) still faces many challenges. Therefore, sample preparation and enrichment are an indispensable link before MS analysis of PTMs in proteomics. The rapid development of functionalized materials with diverse morphologies and compositions provides an avenue for sample preparation and enrichment for PTMs analysis. In this review, we summarize recent advances in the application of novel functionalized materials in sample preparation for phosphoproteomes and glycoproteomes analysis. In addition, this review specifically discusses the design and preparation of functionalized materials based on different enrichment mechanisms, and proposes research directions and potential challenges for proteomic PTMs research.

Preparation of tannic acid and L-cysteine functionalized magnetic composites for synergistic enrichment of N-glycopeptides followed by mass spectrometric analysis

Glycoprotein is involved in a variety of biological activities and has been linked to a number of diseases. Glycopeptide enrichment prior to mass spectrometry (MS) detection is crucial to reduce interference, improve detection efficiency, and analyze proteomics deeply and comprehensively. Here, we prepared a novel magnetic hydrophilic material combining tannic acid (TA) and L-cysteine (L-Cys) through a simple and fast procedure. Owing to the synergistic hydrophilic interaction of TA and L-Cys, the obtained adsorbent material shows excellent enrichment performance toward N-glycopeptides with low detection limit, high selectivity, and good reusability. Besides, the material can also be utilized for the enrichment of N-glycopeptides in human serum and saliva, which shows its application prospect in complex biological samples.

Fe3+-NTA magnetic beads as an alternative to spin column-based phosphopeptide enrichment

Protein phosphorylation is a central mechanism of cellular signal transduction in living organisms. Phosphoproteomic studies systematically catalogue and characterize alterations in phosphorylation states across multiple cellular conditions and are often incorporated into global proteomics experiments. Previously, we found that spin column-based Fe³⁺-NTA enrichment integrated well with our workflow but remained a bottleneck for methods that require higher throughput or a scale that is beyond the capacity of these columns. Here, we compare our well-established spin column-based enrichment strategy with one encompassing magnetic beads. Our data show little difference when using either method in terms of the number of identified phosphopeptides as well as their physicochemical properties. In all, we illustrate how the potentially scalable and automation-friendly magnetic Fe³⁺-NTA beads can seamlessly substitute spin column-based Fe³⁺-NTA agarose beads for global phosphoproteome profiling. SIGNIFICANCE: Protein phosphorylation plays a key role in regulating a multitude of biological processes and can lead to insights into disease pathogenesis. Methodologies which can efficiently enrich phosphopeptides in a scalable and high-throughput manner are essential for profiling dynamic phosphoproteomes. Here we compare two phosphopeptide enrichment workflows, a well-established spin column-based strategy with agarose Fe³⁺-NTA beads and a strategy using magnetic Fe³⁺-NTA beads. Our data suggest that the scalable and automation-friendly magnetic bead-based workflow is an equivalent, but more flexible, enrichment strategy for phosphoproteome profiling experiments.