Strategies for the Construction of Multicyclic Phage Display Libraries.

Peptide therapeutics have gained great interest due to their multiple advantages over small molecule and antibody-based drugs. Peptide drugs are easier to synthesize, have the potential for oral bioavailability, and are large enough to target protein-protein interactions that are undruggable by small molecules. However, two major limitations have made it difficult to develop novel peptide therapeutics not derived from natural products, including the metabolic instability of peptides and the difficulty of reaching antibody-like potencies and specificities. Compared to linear and disulfide-monocyclized peptides, multicyclic peptides can provide increased conformational rigidity, enhanced metabolic stability, and higher potency in inhibiting protein-protein interactions. The identification of novel multicyclic peptide binders can be difficult, however, recent advancements in the construction of multicyclic phage libraries have greatly advanced the process of identifying novel multicyclic peptide binders for therapeutically relevant protein targets. This review will describe the current approaches used to create multicyclic peptide libraries, highlighting the novel chemistries developed and the proof-of-concept work done on validating these libraries against different protein targets.

The Optimized Design of Soil-Touching Parts of a Greenhouse Humanoid Weeding Shovel Based on Strain Sensing and DEM-ADAMS Coupling Simulation.

To overcome the shortcomings of plowing and rotary tillage, a human-like weeding shoveling machine was designed. The machine's various moving rods were analyzed using Matlab R2019b(9.7.0.1190202) software to determine the appropriate entry and cutting conditions, as well as non-cutting conditions. It was concluded that a θ2 of 90° was optimal for cutting the soil and that the shoveling depth was suitable for greenhouse weeding. The Adams and DEM coupled discrete element simulation system was developed for this machine and was used to analyze the rotating shaft torque and shovel bending moment. A strain measurement system based on strain gauges was designed to measure the rotating shaft torque and shovel bar bending moment. A bending moment and torque measurement system was designed to perform field measurement tests for comparison with simulation results. The simulation system's rotating shaft had an average torque error of 6.26%, while the shovel rod's bending moment had an average error of 5.43%. The simulation accuracy was within the acceptable error range. Table U8 (81 × 44) of the Uniform Design of the Mixing Factor Level for the Homogeneous Virtual Simulation Test includes eight levels of forward machine speed ranging from 0.1 to 0.45 m/s and four levels of output shaft speed ranging from 90 to 165 r/min. Crank lengths were set at four levels ranging from 155 to 185 mm, while shovel lengths were set at four levels ranging from 185 to 230 mm. Four types of shovel shapes were proposed, including pointed curved shovels, pointed straight shovels, straight-edged curved shovels, and straight-edged straight shovels. A mathematical model was created via a regression analysis of the results of coupled simulation tests to establish the relationship between shaft torque and shovel rod bending moment, tool advance speed, shaft speed, crank length, tool length, and tool shape. The model was used to determine the optimum working parameters.

Fluorosulfate as a Latent Sulfate in Peptides and Proteins.

Sulfation widely exists in the eukaryotic proteome. However, understanding the biological functions of sulfation in peptides and proteins has been hampered by the lack of methods to control its spatial or temporal distribution in the proteome. Herein, we report that fluorosulfate can serve as a latent precursor of sulfate in peptides and proteins, which can be efficiently converted to sulfate by hydroxamic acid reagents under physiologically relevant conditions. Photocaging the hydroxamic acid reagents further allowed for the light-controlled activation of functional sulfopeptides. This work provides a valuable tool for probing the functional roles of sulfation in peptides and proteins.

Optimized Design of Touching Parts of Soil Disinfection Machine Based on Strain Sensing and Discrete Element Simulation.

With the increasing level in the intensification of agricultural production in China, continuous cropping obstacles have become a problem that needs to be solved. The use of vertical rotary tillage technology and soil disinfection technology is an effective solution. In this paper, a vertical rotary soil-tilling variable disinfection combine was developed and an on-board control system with STM32 as the control core was designed to realize the real-time acquisition of powder monopoly torque information and the variable application of soil disinfection chemicals. Based on the obtained experimental soil parameters, a discrete element soil particle model was established, and orthogonal experiments were conducted to analyze the single-blade roller tillage process, and the optimal operating parameters were finally selected as 500 mm powder monopoly depth, 320 r/min knife roller speed, and 0.26 m/s forward speed, respectively. The field experiment found that the average tillage depth of the implement was 489 mm, the stability coefficient of tillage depth was 94.50%, the uniformity coefficient of soil disinfection was 85.57%, and the applied amount and the speed ratio coefficient of the given flow were linearly related, respectively. This research provides a technical reference for the deep tillage and soil disinfection of the powder monopoly.

A Cysteine-Directed Proximity-Driven Crosslinking Method for Native Peptide Bicyclization.

Efficient and site-specific modification of native peptides and proteins is desirable for synthesizing antibody-drug conjugates as well as for constructing chemically modified peptide libraries using genetically encoded platforms such as phage display. In particular, there is much interest in efficient multicyclization of native peptides due to the appeals of multicyclic peptides as therapeutics. However, conventional approaches for multicyclic peptide synthesis require orthogonal protecting groups or non-proteinogenic clickable handles. Herein, we report a cysteine-directed proximity-driven strategy for the constructing bicyclic peptides from simple natural peptide precursors. This linear to bicycle transformation initiates with rapid cysteine labeling, which then triggers proximity-driven amine-selective cyclization. This bicyclization proceeds rapidly under physiologic conditions, yielding bicyclic peptides with a Cys-Lys-Cys, Lys-Cys-Lys or N-terminus-Cys-Cys stapling pattern. We demonstrate the utility and power of this strategy by constructing bicyclic peptides fused to proteins as well as to the M13 phage, paving the way to phage display of novel bicyclic peptide libraries.

Lysine-Targeting Reversible Covalent Inhibitors with Long Residence Time.

We report a new reversible lysine conjugation that features a novel diazaborine product and much slowed dissociation kinetics in comparison to the previously known iminoboronate chemistry. Incorporating the diazaborine-forming warhead RMR1 to a peptide ligand gives potent and long-acting reversible covalent inhibitors of the staphylococcal sortase. The efficacy of sortase inhibition is demonstrated via biochemical and cell-based assays. A comparative study of RMR1 and an iminoboronate-forming warhead highlights the significance and potential of modulating bond dissociation kinetics in achieving long-acting reversible covalent inhibitors.

Lysine-Targeted Reversible Covalent Ligand Discovery for Proteins via Phage Display.

Binding via reversible covalent bond formation presents a novel and powerful mechanism to enhance the potency of synthetic inhibitors for therapeutically important proteins. Work on this front has yielded the anticancer drug bortezomib as well as the antisickling drug voxelotor. However, the rational design of reversible covalent inhibitors remains difficult even when noncovalent inhibitors are available as a scaffold. Herein, we report chemically modified phage libraries, both linear and cyclic, that incorporate 2-acetylphenylboronic acid (APBA) as a warhead to bind lysines via reversible iminoboronate formation. To demonstrate their utility, these APBA-presenting phage libraries were screened against sortase A of Staphylococcus aureus, as well as the spike protein of SARS-CoV-2. For both protein targets, peptide ligands were readily identified with single-digit micromolar potency and excellent specificity, enabling live-cell sortase inhibition and highly sensitive spike protein detection, respectively. Furthermore, our structure-activity studies unambiguously demonstrate the benefit of the APBA warhead for protein binding. Overall, this contribution shows for the first time that reversible covalent inhibitors can be developed via phage display for a protein of interest. The phage display platform should be widely applicable to proteins including those involved in protein-protein interactions.

Fast Cysteine Bioconjugation Chemistry.

Cysteine bioconjugation serves as a powerful tool in biological research and has been widely used for chemical modification of proteins, constructing antibody-drug conjugates, and enabling cell imaging studies. Cysteine conjugation reactions with fast kinetics and exquisite selectivity have been under heavy pursuit as they would allow clean protein modification with just stoichiometric amounts of reagents, which minimizes side reactions, simplifies purification and broadens functional group tolerance. In this concept, we summarize the recent advances in fast cysteine bioconjugation, and discuss the mechanism and chemical principles that underlie the high efficiencies of the newly developed cysteine reactive reagents.

Fast and Cysteine-Specific Modification of Peptides, Proteins and Bacteriophage Using Chlorooximes.

This work reports a novel chlorooxime mediated modification of native peptides and proteins under physiologic conditions. This method features fast reaction kinetics (apparent k2 =306±4 M-1 s-1 for GSH) and exquisite selectivity for cysteine residues. This cysteine conjugation reaction can be carried out with just single-digit micromolar concentrations of the labeling reagent. The conjugates show high stability towards acid, base, and external thiol nucleophiles. A nitrile oxide species generated in situ is likely involved as the key intermediate. Furthermore, a bis-chlorooxime reagent is synthesized to enable facile Cys-Cys stapling in native peptides and proteins. This highly efficient cysteine conjugation and stapling was further implemented on bacteriophage to construct chemically modified phage libraries.

Cost effectiveness analysis of total laparoscopic hysterectomy versus total abdominal hysterectomy for uterine fibroids in Western China: a societal perspective.

BACKGROUND: As a common female pelvic tumor, uterine fibroids remain the leading cause for hysterectomy in China. Hysterectomy provides a good surgical treatment of uterine fibroids, and it guarantees the removal of all uterine fibroids without lower risk of recurrence. This study compares the cost effectiveness of total laparoscopic hysterectomy (TLH) versus total abdominal hysterectomy (TAH) for women with uterine fibroids from a societal perspective. METHODS: An economic analysis was conducted in 392 patients (TLH n = 75; TAH n = 317), including all relevant costs over a 12-month time horizon. Primary outcome was major surgical complications; secondary outcomes were postoperative discomfort symptoms and time of return to normal activities. Clinical, outcomes and costs data were collected from medical records, telephone survey and financial information system. Generalized linear models were used to assess costs and outcomes differences between the two groups. Incremental cost effectiveness ratio (ICER) was used to estimate the cost effectiveness. RESULTS: Mean direct costs were $2,925.71 for TLH, $2,436.24 for TAH, respectively. Mean indirect costs were $1,133.22 for TLH, $1,394.85 for TAH, respectively. Incremental societal costs were $256.86 (95%CI: 249.03-264.69). Mean differences in outcome were: 4.53% (95%CI: 4.35-4.71) for major surgical complications; 6.75% (95%CI: 6.45-7.05) for postoperative discomfort symptoms; 1.27 (95%CI: 1.23-1.30) weeks for time to return to normal activities. ICER of TLH was $5,669.16 (95%CI: 5,384.76-5,955.56) per complication averted, $3,801.54 (95%CI: 3,634.81-3,968.28) per postoperative discomfort symptoms averted and $202.96 (95%CI: 194.97-210.95) per week saved to return to normal activities. CONCLUSIONS: TLH is cost effective compared with TAH in preventing additional complications based on our estimated conservative threshold in China. The findings provide useful information for researchers to conduct further cost effectiveness analysis based on prospective study which can provide stronger and more evidence, in China. In addition, the data may be useful for Chinese health care policy-makers and medical insurance payers to make related health care decisions.

Identifying peripheral arterial disease in the elderly patients using machine-learning algorithms.

BACKGROUND: Peripheral artery disease (PAD) is a common syndrome in elderly people. Recently, artificial intelligence (AI) algorithms, in particular machine-learning algorithms, have been increasingly used in disease diagnosis. AIM: In this study, we designed an effective diagnostic model of PAD in the elderly patients using artificial intelligence. METHODS: The study was performed with 539 participants, all over 80 years in age, who underwent the measurements of Doppler ultrasonography and ankle-brachial pressure index (ABI). Blood samples were collected. ABI and two machine-learning algorithms (MLAs)-logistic regression and a random forest (RF) model-were established to diagnose PAD. The sensitivity and specificity of the models were analyzed. An additional RF model was designed based on the most significant features of the original RF model and a prospective study was conducted to demonstrate its external validity. RESULTS: Thirteen of the 28 features introduced to the MLAs differed significantly between PAD and non-PAD participants. The respective sensitivities and specificities of logistic regression, RF, and ABI were as follows: logistic regression (81.5%, 83.8%), RF (89.3%, 91.6%) and ABI (85.1%, 84.5%). In the prospective study, the newly designed RF model based on the most significant seven features exhibited an acceptable performance rate for the diagnosis of PAD with 100.0% sensitivity and 90.3% specificity. CONCLUSIONS: An RF model was a more effective method than the logistic regression and ABI for the diagnosis of PAD in an elderly cohort.

Exploring the relationship between functional limitations of the older adults and the health-related quality of life of their spouse in Shaanxi Province, China.

BACKGROUND: With trends towards longer life expectancy, lifetime with disability has also been prolonged. It is increasingly recognized that not only the person with disability but also those around them are affected. The relationship between functional limitation (FL) of the older adults and health-related quality of life (HRQoL) of their spouse is of interest. So too is the determination of the factors aside from FL that influence HRQoL. METHODS: The sample was derived from the 2013 National Health Service Survey conducted in Shaanxi Province in China. Married couples aged ≥ 60 years were selected (n = 3463). The European quality of life five dimensions (EQ-5D) and visual analogue scale were used to measure HRQoL. RESULTS: Both wife and husband reported lower HRQoL if either the male or female partner had some or serious FLs (P < 0.001). Other factors associated with lower HRQoL of the spouse included age, lower educational level, presence of chronic disease, and lower household economic status. Family size was associated with wife's HRQoL only when the male had no FL and lived with another 1-2 persons, or when the male had some FLs and lived in a larger family (n ≥ 5). Residential status did not relate to the HRQoL of spouses regardless of FL status. CONCLUSIONS: Older adults in Shaanxi province who have partners with FLs tend to report poorer EQ-5D, suggesting that couples amongst whom one has FL may be particularly vulnerable to lower HRQoL.

High precision measurement for the chamfered hole radius and spacing of a large-size workpiece based on binocular vision combined with plane dynamic adjustment.

A novel, to the best of our knowledge, hole radius and spacing measurement method is presented based on binocular vision combined with dynamic local plane for the large-size workpiece with plane feature. The novel method overcomes the problem of the ariable working distance and large location error of an abrupt edge for conventional methods. Its measurement principle and model are introduced. Then, a chamfered inner edge extraction method based on the shrinkage of an elliptical band and an adaptive weight optimal calculation based on redundant measurement data are presented to improve the measurement accuracy. Experiments are carried out to validate the presented method, and a high measurement accuracy with a standard deviation of 0.017 mm in the hole radius and 0.021 mm in hole spacing have eventually been achieved for the actual measurement workpieces, respectively. Compared with the common method, the measurement accuracy is improved by at least 77% and 53% in radius and spacing, respectively.

Repeat abortion and associated factors among women seeking abortion services in northwestern China: a cross-sectional study.

BACKGROUND: Repeat abortion is a significant public health problem in China. International knowledge about repeat abortion and its associated factors in Chinese women is scarce. This study aimed to analyze the prevalence of repeat abortion among women seeking abortion services with unintended pregnancies in northwestern China and to identify factors associated with the repeat abortion from both two perspectives of abortion seekers themselves and their sexual partners. METHODS: This cross-sectional survey was conducted from May 1st to May 31st, 2020, in 90 medical institutions in Xi'an, the largest city in northwestern China. All women seeking abortions within the first 12 weeks of pregnancy were invited to participate in this survey; however, only those abortion seekers with unintended pregnancies were extracted and included in this study. Pearson's chi-squared tests, Kolmogorov-Smirnov tests, and binary logistic regression analysis were performed. RESULTS: Of 3397 abortion seekers, 56.6% (1924) were undergoing repeat abortions. Participants who were older than 30 years (OR: 1.37, 95% CI: 1.08-1.73 for 31-35 years; 1.82, 1.29-2.57 for ≥36 years), received a low-level education (1.86, 1.42-2.43 for ≤senior high school; 1.46, 1.17-1.83 for junior college), were jobless (2.46, 1.18-5.13), had one child (1.54, 1.10-2.17), had a general (1.60, 1.28-1.98) or no (2.51, 2.02-3.11) cognition of possible adverse health effects of having abortions, and had used contraception at the time of conception, i.e., condoms (1.33, 1.09-1.61), withdrawal (1.43, 1.12-1.84), and emergency measures (1.48, 1.09-1.99) were more likely to undergo a repeat abortion. Besides, participants whose sexual partners were older than 30 years (1.33, 1.06-1.68 for 31-35 years; 2.13, 1.56-2.91 for ≥36 years), attained a low-level education (1.66, 1.28-2.15 for ≤senior high school; 1.38, 1.10-1.74 for junior college), received a high-level monthly income (1.34, 1.08-1.65 for ≥6001 Yuan), and had a weak or very weak willingness to use contraception (6.84, 2.42-19.33) were more likely to have a repeat abortion. CONCLUSIONS: The study findings highlight the problem of repeat abortion in China and suggest the need for government and civil society to increase efforts to reduce the risks of unintended pregnancy and repeat abortion in China. One approach may be to offer better access to reproductive health and contraception knowledge to women and their sexual partners and to promote their correct, consistent, and effective contraception practice.

N, S-Double Labeling of N-Terminal Cysteines via an Alternative Conjugation Pathway with 2-Cyanobenzothiazole.

Conjugation of 2-cyanobenzothiazole (CBT) with N-terminal cysteines (NCys) typically gives a luciferin product. We herein report an alternative reaction pathway leading to an N-terminal amidine rendering the side chain thiol available for further modification. Examination of peptide sequence dependence of this amidine conjugation reveals a tripeptide tag CIS that allows facile N, S-double labeling of a protein of interest with >90% yield. This alternative reaction pathway of CBT-NCys condensation presents a significant addition to the toolbox for site-specific protein modifications.

Influence of China's 2009 healthcare reform on the utilisation of continuum of care for maternal health services: evidence from two cross-sectional household surveys in Shaanxi Province.

BACKGROUND: Continuum of care for maternal health services (CMHS) is a proven approach to improve health and safety for mothers and newborns. This study aims to explore the influence of China's 2009 healthcare reform on improving the CMHS utilisation. METHODS: This population-based cross-sectional quantitative study included 2332 women drawn from the fourth and fifth National Health Service Surveys of Shaanxi Province, conducted in 2008 and 2013 respectively, before and after China's 2009 healthcare reform. A generalised linear mixed model (GLMM) was applied to analyse the influence of this healthcare reform on utilisation of CMHS. Concentration curves, concentration indexes and its decomposition method were used to analyse the equity of changes in utilisation. RESULTS: This study showed post-reform CMHS utilisation was higher in both rural and urban women than the CMHS utilisation pre-reform (according to China's policy defining CMHS). The rate of CMHS utilisation increased from 24.66 to 41.55% for urban women and from 18.31 to 50.49% for rural women (urban: χ2 = 20.64, P < 0.001; rural: χ2 = 131.38, P < 0.001). This finding is consistent when the WHO's definition of CMHS is applied for rural women after reform (12.13% vs 19.26%; χ2 = 10.99, P = 0.001); for urban women, CMHS utilisation increased from 15.70 to 20.56% (χ2 = 2.57, P = 0.109). The GLMM showed that the rate of CMHS utilisation for urban women post-reform was five times higher than pre-reform rates (OR = 5.02, 95%CL: 1.90, 13.31); it was close to 15 times higher for rural women (OR = 14.70, 95%CL: 5.43, 39.76). The concentration index for urban women decreased from 0.130 pre-reform (95%CI: - 0.026, 0.411) to - 0.041 post-reform (95%CI: - 0.096, 0.007); it decreased from 0.104 (95%CI: - 0.012, 0.222) to 0.019 (95%CI: - 0.014, 0.060) for rural women. The horizontal inequity index for both groups of women also decreased (0.136 to - 0.047 urban and 0.111 to 0.019 for rural). CONCLUSIONS: China's 2009 healthcare reform has positively influenced utilisation rates and equity of CMHS's utilisation among both urban and rural women in Shaanxi Province. Addressing economic and educational attainment gaps between the rich and the poor may be effective ways to improve the persistent health inequities for rural women.

Phase-modulation combined deflectometry for small defect detection.

Deflectometry has been widely used to detect defects on specular surfaces. However, it is still very challenging to detect defects on semispecular or diffuse surfaces because of the low contrast and low signal-to-noise ratio. To address this challenge, we proposed a phase-modulation combined method for accurate defect detection. Based on the phase and modulation of captured fringes, a dual-branch convolutional neural network is employed to simultaneously extract geometric and photometric features from the phase-shifting pattern sequence and modulation, which improves the defect detection performance significantly. Compared to state-of-the-art methods, we believe the results demonstrated the proposed method's effectiveness and capability to reduce false positives.

Decomposing differences in depressive symptoms between older rural-to-urban migrant workers and their counterparts in mainland China.

BACKGROUND: There has been an increase in older rural-to-urban migrant workers (aged 50 and above) in mainland China, little known about their depressive symptoms. The aim of this study was to identify depressive symptoms among older rural-to-urban migrant workers, as well as explored the factors leading to differences in depressive symptoms between older rural-to-urban migrant workers and their rural counterparts (older rural dwellers) and urban counterparts (older urban residents) in mainland China. The results provided a comprehensive understanding of the depressive symptoms of older rural-to-urban migrant workers, and had great significance for improving the depressive symptoms for this vulnerable group. METHODS: Data were derived from the China Health and Retirement Longitudinal Study (CHARLS) conducted in 2015, and coarsened exact matching (CEM) method was employed to control confounding factors. This study employed a Chinese version 10-item short form of the Center for Epidemiologic Studies-Depression Scale (CES-D 10) to measure depressive symptoms, and used the Social-Ecological Model as a framework to explore influential factors related to depressive symptoms. Specifically, the approach of Fairlie's decomposition was used to parse out differences into observed and unobserved components. RESULTS: After matching, our findings indicated that the prevalence of depressive symptoms in older rural-to-urban migrant workers was lower than older rural dwellers; and the prevalence of depressive symptoms in older rural-to-urban migrant workers was higher than older urban residents. Fairlie's decomposition analysis indicated that type of in-house shower, sleeping time at night and ill in the last month were proved to be major contributors to the differences in depressive symptoms between older rural-to-urban migrant workers and older rural dwellers; self-reported health and sleeping time at night were proved to be major contributors to the differences in depressive symptoms between older rural-to-urban migrant workers and older urban residents. CONCLUSIONS: Differences in depressive symptoms between older rural-to-urban migrant workers and their rural and urban counterparts did exist. Our findings contributed to a more reliable understanding in depressive symptoms among older rural-to-urban migrant workers. Our findings would be of referential significance for improving older rural-to-urban migrant workers' depressive symptoms.

Fast and Stable N-Terminal Cysteine Modification through Thiazolidino Boronate Mediated Acyl Transfer.

We report a novel conjugation of N-terminal cysteines (NCys) that proceeds with fast kinetics and exquisite selectivity, thereby enabling facile modification of NCys-bearing proteins in complex biological milieu. This new NCys conjugation proceeds via a thiazolidine boronate (TzB) intermediate that results from fast (k2 : ≈5000 m-1 s-1 ) and reversible conjugation of NCys with 2-formylphenylboronic acid (FPBA). We designed a FPBA derivative that upon TzB formation elicits intramolecular acyl transfer to give N-acyl thiazolidines. In contrast to the quick hydrolysis of TzB, the N-acylated thiazolidines exhibit robust stability under physiologic conditions. The utility of the TzB-mediated NCys conjugation is demonstrated by rapid and non-disruptive labeling of two enzymes. Furthermore, applying this chemistry to bacteriophage allows facile chemical modification of phage libraries, which greatly expands the chemical space amenable to phage display.

Versatile Bioconjugation Chemistries of ortho-Boronyl Aryl Ketones and Aldehydes.

Biocompatible and bioorthogonal conjugation reactions have proven to be powerful tools in biological research and medicine. While the advent of bioorthogonal conjugation chemistries greatly expands our capacity to interrogate specific biomolecules in situ, biocompatible reactions that target endogenous reactive groups have given rise to a number of covalent drugs as well as a battery of powerful research tools. Despite the impressive progress, limitations do exist with the current conjugation chemistries. For example, most known bioorthogonal conjugations suffer from slow reaction rates and imperfect bioorthogonality. On the other hand, covalent drugs often display high toxicity due to off-target labeling and immunogenicity. These limitations demand continued pursuit of conjugation chemistries with optimal characteristics for biological applications. A spate of papers appearing in recent literature report the conjugation chemistries of 2-formyl and 2-acetyl phenylboronic acids (abbreviated as 2-FPBA and 2-APBA, respectively). These simple reactants are found to undergo fast conjugation with various nucleophiles under physiological conditions, showing great promise for biological applications. The versatile reactivity of 2-FPBA and 2-APBA manifests in dynamic conjugation with endogenous nucleophiles as well as conjugation with designer nucleophiles in a bioorthogonal manner. 2-FPBA/APBA conjugates with amines in biomolecules, such as lysine side chains and aminophospholipids, in a highly dynamic manner to give iminoboronates. In contrast to typical imines, iminoboronates enjoy much improved thermodynamic stability, yet are kinetically labile for hydrolysis due to imine activation by the boronic acid. Dynamic conjugations as such present a novel binding mechanism analogous to hydrogen bonding and electrostatic interactions. Implementation of this covalent binding mechanism has yielded reversible covalent probes of prevalent bacterial pathogens. It has also resulted in reversible covalent inhibitors of a therapeutically important protein Mcl-1. Such covalent probes/inhibitors with 2-FPBA/APBA warheads avoid permanent modification of their biological target, potentially able to mitigate off-target labeling and immunogenicity of covalent drugs. The dynamic conjugation of 2-FPBA/APBA has been recently extended to N-terminal cysteines, which can be selectively targeted via formation of a thiazolidino boronate (TzB) complex. The dynamic TzB formation expands the toolbox for site-specific protein labeling and the development of covalent drugs. On the front of bioorthogonal conjugation, 2-FPBA/APBA has been found to conjugate with α-nucleophiles under physiologic conditions with rate constant ( k2) over 1000 M-1 s-1, which overcomes the slow kinetics problems and rekindles the interest of using the conjugation of α-nucleophiles for biological studies. With fast kinetics being a shared feature, this family of conjugation chemistries gives remarkably diverse product structures depending on the choice of nucleophile. Importantly, both dynamic and irreversible conjugations have been developed, which we believe will enable a wide array of applications in biological research. In this Account, we collectively examine this rapidly expanding family of conjugation reactions, seeking to elucidate the unifying principles that would guide further development of novel conjugation reactions, as well as their applications in biology.