A systematic genome-wide analysis and screening of the NAC family genes related to wood formation in Cinnamomum camphora.

Many processes, such as growth, aging, and adaptation to abiotic stress, are regulated in plants by NAC transcription factors. In woody plants, NAC transcription factors acts as a primary switch that regulates secondary xylem development by activating various downstream transcription factors and modulating expression levels of genes involved in the synthesis of the secondary cell wall. Our team had previously sequenced the whole genome of the camphor tree (Cinnamomum camphora). Here, we performed a detailed analysis of the NAC gene family of C. camphora and examined its evolutionary history. The genomic sequences of 121 NAC genes of C. camphora were identified and classified into 20 subfamilies in 2 major classes based on the phylogenetic analysis and structural features. Expansion of the CcNAC gene family occurred mainly by fragment replication and was influenced by the purifying selection. By analyzing predicted interactions of the homologous AtNAC proteins, we identified five CcNACs that potentially regulate xylem development in C. camphora. RNA sequencing revealed distinct expression profiles of CcNACs in seven different plant tissues. Subcellular localization prediction revealed that 120, 3, and 2 CcNACs have biological functions in the nucleus, cytoplasm, and chloroplast, respectively. Furthermore, we verified expression patterns of five CcNACs (CcNAC012, CcNAC028, CcNAC055, CcNAC080, and CcNAC119) in various tissue types using qRT-PCR. Our results will facilitate further in-depth studies of the molecular mechanisms by which CcNAC transcription factors regulate wood formation and other processes in C. camphora.

Genome-Wide Characterization and Analysis of bHLH Transcription Factors Related to Anthocyanin Biosynthesis in Cinnamomum camphora ('Gantong 1').

Cinnamomum camphora is one of the most commonly used tree species in landscaping. Improving its ornamental traits, particularly bark and leaf colors, is one of the key breeding goals. The basic helix-loop-helix (bHLH) transcription factors (TFs) are crucial in controlling anthocyanin biosynthesis in many plants. However, their role in C. camphora remains largely unknown. In this study, we identified 150 bHLH TFs (CcbHLHs) using natural mutant C. camphora 'Gantong 1', which has unusual bark and leaf colors. Phylogenetic analysis revealed that 150 CcbHLHs were divided into 26 subfamilies which shared similar gene structures and conserved motifs. According to the protein homology analysis, we identified four candidate CcbHLHs that were highly conserved compared to the TT8 protein in A. thaliana. These TFs are potentially involved in anthocyanin biosynthesis in C. camphora. RNA-seq analysis revealed specific expression patterns of CcbHLHs in different tissue types. Furthermore, we verified expression patterns of seven CcbHLHs (CcbHLH001, CcbHLH015, CcbHLH017, CcbHLH022, CcbHLH101, CcbHLH118, and CcbHLH134) in various tissue types at different growth stages using qRT-PCR. This study opens a new avenue for subsequent research on anthocyanin biosynthesis regulated by CcbHLH TFs in C. camphora.

How to capitalize on investors by using information presentation and feedback on crowdfunding projects.

As an innovative financing activity, online crowdfunding is characterized by extremely high information asymmetry. To reduce this information asymmetry, crowdfunding companies typically use information presentation, feedback, and other means to convey more information about the fundraising project to investors. Whether the information presentation and feedback affect the investment behavior of nonprofessional ordinary investors is yet to be determined. Moreover, the method by which the information presentation and feedback influence the investment behavior and consequently, the financing performance of crowdfunding companies, has to be identified as well. Currently, research on this subject remains deficient. Therefore, with signal theory and the difference in the cost of information transmission considered, this study classifies the information released by fundraisers on the crowdfunding platform into two categories: low-quality signal and high-quality signal. Projects on the JD.com Crowdfunding website are then used as research samples to explore how the difference in signal quality in the information presentation and feedback of crowdfunding projects influences financing performance from the perspective of investors. The results show that low-quality signals such as video duration, the number of updates, and the number of comments on projects positively affect the success of crowdfunding; meanwhile, crowdfunding experience, which represents high-quality signals, positively moderates the relationship between project video duration, project updates, and crowdfunding success.

Identification of Key Genes Related to the Obesity Patients with Osteoarthritis Based on Weighted Gene Coexpression Network Analysis (WGCNA).

Background: Increasing evidence has suggested that obesity affects the occurrence and progression of osteoarthritis (OA). However, the underlying molecular mechanism that obesity affects the course of OA is not fully understood and remains to be studied. Methods: The gene expression profiles of the GSE117999 and GSE98460 datasets were derived from the Gene Expression Omnibus (GEO) database. Firstly, we explored the correlation between obesity and OA using chi-square test. Next, weighted gene coexpression network analysis (WGCNA) was executed to identify obesity patients with OA- (obesity OA-) related genes in the GSE117999 dataset by "WGCNA" package. Moreover, differential expression analysis was performed to select the hub genes by "limma" package. Furthermore, ingenuity pathway analysis (IPA) and functional enrichment analysis ("clusterProfiler" package) were conducted to investigate the functions of genes. Finally, the regulatory networks of hub genes and protein-protein interaction (PPI) network were created by the Cytoscape 3.5.1 software and STRING. Results: A total of 15 differentially expressed obesity OA-related genes, including 9 lncRNAs and 6 protein coding genes, were detected by overlapping 66 differentially expressed genes (DEGs) between normal BMI samples and obesity OA samples and 451 obesity OA-related genes. Moreover, CCR10, LENG8, QRFPR, UHRF1BP1, and HLA-DRB4 were identified as hub genes. IPA results indicated that the hub genes were noticeably enriched in antimicrobial response, inflammatory response, and humoral immune response. PPI network showed that CCR10 interacted more with other proteins. Gene set enrichment analysis (GSEA) indicated that the hub genes were related to protein translation, cancer, chromatin modification, antigen processing, and presentation. Conclusion: Our results further demonstrated the role of obesity in OA and might provide new targets for the treatment of obesity OA.

Oblique-ilioischial plate technique: a novel method for acetabular fractures involving low posterior column.

BACKGROUND: Complex acetabular fractures involving the anterior and posterior columns are an intractable clinical challenge. The study investigated the safety and efficacy of oblique-ilioischial plate technique for acetabular fractures involving low posterior column. METHODS: A retrospective analysis of 18 patients operated with the oblique-ilioischial plate technique by the modified Stoppa approach (or combined with iliac fossa approach) between August 2016 and July 2021 for low posterior column acetabular fractures was conducted. The anterior column was fixed with a reconstructed plate from the iliac wing along the iliopectineal line to the pubis. The low posterior column was fixed with the novel oblique-ilioischial plate running from the ilium to the ischial ramus. Operative time, intraoperative blood loss, reduction quality, and postoperative hip function were recorded. RESULTS: Out of the 18 patients, 10 were male and 8 were female. The mean age was 48.6±10.2 years (range: 45-62 years); The mean interval from injury to operation was 7.2±1.4 days (range: 5-19 days); The mean operative time was 2.1±0.3 h (range: 1.0-3.2 hours); The mean intraoperative blood loss was 300±58.4 mL (range: 200-500 mL). Postoperative reduction (Matta's criteria) was deemed as excellent (n = 9), good (n = 4), and fair (n = 5). At the final follow-up, the hip function (modified Merle d'Aubigne-Postel scale) was deemed as excellent (n = 11), good (n = 3), and fair (n = 4). The mean union time was 4.5±1.8 months (range: 3-6 months). No implant failure, infection, heterotopic ossification, or neurovascular injury were reported. CONCLUSION: The oblique-ilioischial plate technique via anterior approach for acetabular fractures involving low posterior column offers reliable fixation, limited invasion, little intraoperative bleeding, and fewer complications. However, larger multicenter control studies are warranted.

Exploiting Self-Association to Evaluate Enantiomeric Composition by Cyclic Ion Mobility-Mass Spectrometry.

The characterization of enantiomers is an important analytical challenge in the chemical and life sciences. Thorough evaluation of the purity of chiral molecules is particularly required in the pharmaceutical industry where safety concerns are paramount. Assessment of the enantiomeric composition is still challenging and time-consuming, meaning that alternative approaches are required. In this study, we exploit the formation of dimers as diastereomeric pairs of enantiomers to affect separation by high resolution cyclic ion mobility-mass spectrometry. Using the example of (R/S)-thalidomide, we show that even though this is not an enantiomer separation, we can determine which enantiomer is in excess and obtain quantitative information on the enantiomer composition without the need for a chiral modifier. Further examples of the approach are presented, including d/l-tryptophan and (R/S)-propanolol, and demonstrate the need for mobility resolving power in excess of 400 (CCS/ΔCCS).

A New Method to Develop the Primate Model of Knee Osteoarthritis With Focal Cartilage Defect.

Objective: Osteoarthritis (OA) is a common degenerative joint disease, and animal models have proven pivotal in investigating this disease. This study aimed to develop a primate model of OA that may be more relevant to research studies on OA in humans. Method: Twelve female rhesus macaques were randomly divided into three groups. Four animals were untreated (Control group); four were subjected to the modified Hulth method, involving cutting of the anterior and posterior cruciate ligaments, and transecting the meniscus (Hulth group); and four were subjected to the modified Hulth method combined with cartilage defect (MHCD group). Each primate was subjected to motor ability tests, and underwent arthroscopic, radiographic, morphological, and pathological observation of the knee joints at various times for up to 180 days. Results: Motor ability on Day 180 was significantly lower in the MHCD group than in the Control (p＜0.01) and Hulth (p＜0.05) groups. Radiographic and morphological examination showed that the severity of knee joint deformity and articular cartilage injury were greater in the MHCD group than in the other groups. Pathological examination showed that cartilage thickness was significantly lower in the MHCD group than in the other groups at the same time points. The Mankin score on Day 180 was markedly higher in the MHCD group than in the Hulth (p＜0.05) and Control (p＜0.001) groups. Conclusion: The MHCD model of OA closely resembles the pathophysiological processes of spontaneous knee OA in humans. The time required to develop knee OA is shorter using the MHCD model than using the Hulth method.

Correction to: Molecular diversity of arbuscular mycorrhizal fungal communities across the gradient of alkaline Fe ore tailings, revegetated waste rock to natural soil sites.

The authors thank the Australian Centre for Ecogenomics in the University of Queensland for conducting Illumina sequencing.

Molecular diversity of arbuscular mycorrhizal fungal communities across the gradient of alkaline Fe ore tailings, revegetated waste rock to natural soil sites.

Arbuscular mycorrhizal (AM) fungi are important to the establishment of native vegetation for mined land rehabilitation, particularly in semi-arid and infertile landscapes. However, the information has been scarce about the colonization of AM fungal community in alkaline magnetite Fe ore tailing sites (without toxic metal (loid) contamination). The present study has characterized the diversity of AM fungi across typical domains of a magnetite Fe ore mine located in 200 km south-east of Geraldton, Western Australia, by adopting high throughput Illumina Miseq sequencing. The investigated domains included two tailing sites without top soil covering (T1 and T2), a rehabilitated area of tailings with top soil covering (R1), a revegetated waste rock area (R2), and two native undisturbed soil sites (S1 and S2). The results indicated that the T1/T2 sites had different AM fungal community structure, compared with R1/R2 and S1/S2 sites. The dominant families were Glomeraceae, Claroideoglomeraceae, Archaeosporaceae, Ambisporaceae, and Paraglomeraceae, with Paraglomeraceae (more than 50%) as the most abundant in the T1/T2 and R1/R2 sites. At genus level, Ambispora spp. and Archaeospora spp. were rich in T1/T2 sites (> 10%), while Glomus spp. were preferably dominant in S1/S2 sites (> 10%). Furthermore, amorphous Fe and available P were found to explain the variations associated with AM fungal community composition, particularly the abundance of Archaeosporaceae and Glomeraceae. The study revealed the AM fungal community composition shift across the gradient of Fe ore mine sites, as well as the effects of revegetation on AM fungal community development. The findings indicate the possible restoration of AM fungal community in the tailings undergoing revegetation, and potential adoption of indigenous AM fungi to rapid phytostabilization of the Fe ore tailings under semi-arid climatic conditions.

A combination of the modified Stoppa approach and the iliac fossa approach in treating compound acetabular fractures by using an anterior ilioischial plate.

Most compound acetabular fractures involving both the anterior and posterior columns are caused by high-energy injuries. Patients with compound acetabular fractures are often in critical or poor condition and cannot tolerate major surgery. This study aims to investigate the effectiveness of an ilioischial plate in treating compound acetabular fractures. A consecutive series of 40 patients with complex acetabular fractures were surgically treated and retrospectively reviewed. A modified Stoppa approach in combination with an iliac fossa approach was used. In all of the cases, the anterior column was stabilized with reconstruction plates for the iliac wing and along the iliopectineal line to the pubis. The posterior column was fixed either with the newly developed ilioischial plate running from the ilium to the ischial ramus or with standard fixation techniques. These included either conventional posterior column screws or quadrilateral plate fixation. Patients were divided into an experimental group (ilioischial plate for posterior column fixation) and a control group (standard fixation techniques). In both groups, we found that 90% of all reductions were good to excellent. According to the modified Merle Aubigne and Postel scoring system, the percentage of good to excellent was 85% in the experimental group as compared to 80% in the control group. Compared with the control group, physical function (PF), role physical (RP) and social function (SF) were significantly better in the experimental group (P<0.05). Fracture healing was achieved in all patients. By using the modified Stoppa approach combined with the iliac fossa approach, the ilioischial plate can be directly fixed to the posterior column and the ilium to stabilize the posterior column in patients with complex acetabular fractures.

A methyltransferase gene from arbuscular mycorrhizal fungi involved in arsenic methylation and volatilization.

Arbuscular mycorrhizal fungi (AMF), ubiquitous symbiotic fungi associated with the majority of terrestrial plants, were demonstrated to play important roles in arsenic (As) translocation and transformation in the plant-soil continuum, and substantially influence plant As tolerance. However, the direct involvement of AMF in As methylation and volatilization and their molecular mechanisms remain unsolved. Here, an arsenite methyltransferase gene RiMT-11 was identified and characterized from AM fungus Rhizophagus irregularis. Heterologous expression of RiMT-11 enhanced arsenite resistance of E. coli (Δars) through methylating As into monomethylarsonic acid (MMA), dimethylarsinic acid (DMA) and ultimately volatile trimethyl arsine (TMAs). In a two-compartment in vitro monoxenic cultivation system, methylated and volatile As were also detected from AM symbioses with arsenate addition, accompanied by strong up-regulation of RiMT-11 expression in extraradical hyphae. The present study provided direct evidence and illustrated an underlying mechanism of As methylation and volatilization by AMF, leading to a deeper insight into the role of AMF in As biogeochemical cycling.

Restoration with pioneer plants changes soil properties and remodels the diversity and structure of bacterial communities in rhizosphere and bulk soil of copper mine tailings in Jiangxi Province, China.

To unravel the ecological function played by pioneer plants in the practical restoration of mine tailings, it is vital to explore changes of soil characteristics and microbial communities in rhizosphere and bulk soil following the adaptation and survival of plants. In the present study, the diversity and structure of rhizospheric bacterial communities of three pioneer plants in copper mine tailings were investigated by Illumina MiSeq sequencing, and the effects of pioneer plants on soil properties were also evaluated. Significant soil improvement was detected in rhizospheric samples, and Alnus cremastogyne showed higher total organic matter, total nitrogen, and available phosphorus than two other herbaceous plants. Microbial diversity indices in rhizosphere and bulk soil of reclaimed tailings were significantly higher than bare tailings, even the soil properties of bulk soil in reclaimed tailings were not significantly different from those of bare tailings. A detailed taxonomic composition analysis demonstrated that Alphaproteobacteria and Deltaproteobacteria, Chloroflexi, Acidobacteria, and Gemmatimonadetes showed significantly higher relative abundance in rhizosphere and bulk soil. In contrast, Gammaproteobacteria and Firmicutes were abundant in bare tailings, in which Bacillus, Pseudomonas, and Lactococcus made up the majority of the bacterial community (63.04%). Many species within known heavy metal resistance and nutrient regulatory microorganism were identified in reclaimed tailings, and were more abundant among rhizospheric microbes. Hierarchical clustering and principal coordinate analysis (PCoA) analysis demonstrated that the bacterial profiles in the rhizosphere clustered strictly together according to plant types, and were distinguishable from bulk soil. However, we also identified a large shared OTUs that occurred repeatedly and was unaffected by highly diverse soil properties in rhizosphere and bulk samples. Redundancy analysis indicated that water content and Cu and As concentrations were the main environmental regulators of microbial composition. These results suggest that the interactive effect of pioneer plants and harsh soil environmental conditions remodel the specific bacterial communities in rhizosphere and bulk soil in mine tailings. And A. cremastogyne might be approximate candidate for phytoremediation of mine tailings for better soil amelioration effect and relative higher diversity of bacterial community in rhizosphere.

Chromium immobilization by extra- and intraradical fungal structures of arbuscular mycorrhizal symbioses.

Arbuscular mycorrhizal (AM) fungi can enhance plant Cr tolerance through immobilizing Cr in mycorrhizal roots. However, the detailed processes and mechanisms are unclear. The present study focused on cellular distribution and speciation of Cr in both extraradical mycelium (ERM) and mycorrhizal roots exposed to Cr(VI) by using field emission scanning electron microscopy equipped with energy dispersive X-ray spectrometer (FE-SEM-EDS), scanning transmission soft X-ray microscopy (STXM) and X-ray absorption fine structure (XAFS) spectroscopy techniques. We found that amounts of particles (possibly extracellular polymeric substances, EPS) were produced on the AM fungal surface upon Cr(VI) stress, which contributed greatly to Cr(VI) reduction and immobilization. With EDS of the surface of AM fungi exposed to various Cr(VI) levels, a positive correlation between Cr and P was revealed, suggesting that phosphate groups might act as counter ions of Cr(III), which was also confirmed by the XAFS analysis. Besides, STXM and XAFS analyses showed that Cr(VI) was reduced to Cr(III) in AM fungal structures (arbuscules, intraradical mycelium, etc.) and cell walls in mycorrhizal roots, and complexed possibly with carboxyl groups or histidine analogues. The present work provided evidence of Cr immobilization on fungal surface and in fungal structures in mycorrhizal roots at a cellular level, and thus unraveled the underlying mechanisms by which AM symbiosis immobilize Cr.

The molecular diversity of arbuscular mycorrhizal fungi in the arsenic mining impacted sites in Hunan Province of China.

Arbuscular mycorrhizal fungi (AMF) can establish a mutualistic association with most terrestrial plants even in heavy metal contaminated environments. It has been documented that high concentrations of toxic metals, such as arsenic (As) in soil could adversely affect the diversity and function of AMF. However, there are still gaps in understanding the community composition of AMF under long-term As contaminations. In the present study, six sampling sites with different As concentrations were selected in the Realgar mining area in Hunan Province of China. The AMF biodiversity in the rhizosphere soils of the dominant plant species was investigated by sequencing the nuclear small subunit ribosomal RNA (SSU rRNA) gene fragments using 454-pyrosequencing technique. A total of 11 AMF genera were identified, namely Rhizophagus, Glomus, Funneliformis, Acaulospora, Diversispora, Claroideoglomus, Scutellopora, Gigaspora, Ambispora, Praglomus, and Archaeospora, among which Glomus, Rhizophagus, and Claroideoglomus clarodeum were detected in all sampling sites, and Glomus was the dominant AMF genus in the Realgar mining area. Redundancy analysis indicated that soil pH, total As and Cd concentrations were the main factors influencing AMF community structure. There was a negative correlation between the AMF species richness and the total As concentration in the soil, but no significant correlation between the Shannon-Wiener index of the AMF and plants. Our study showed that high As concentrations can exert a selective effect on the AMF populations.

Transformation and Immobilization of Chromium by Arbuscular Mycorrhizal Fungi as Revealed by SEM-EDS, TEM-EDS, and XAFS.

Arbuscular mycorrhizal fungi (AMF), ubiquitous soil fungi that form symbiotic relationships with the majority of terrestrial plants, are known to play an important role in plant tolerance to chromium (Cr) contamination. However, the underlying mechanisms, especially the direct influences of AMF on the translocation and transformation of Cr in the soil-plant continuum, are still unresolved. In a two-compartment root-organ cultivation system, the extraradical mycelium (ERM) of mycorrhizal roots was treated with 0.05 mmol L(-1) Cr(VI) for 12 days to investigate the uptake, translocation, and transformation of Cr(VI) by AMF using inductively coupled plasma mass spectrometry (ICP-MS), scanning electron microscopy equipped with energy-dispersive spectroscopy (SEM-EDS), transmission electron microscopy equipped with energy-dispersive spectroscopy (TEM-EDS), and X-ray-absorption fine structure (XAFS) technologies. The results indicated that AMF can immobilize quantities of Cr via reduction of Cr(VI) to Cr(III), forming Cr(III)-phosphate analogues, likely on the fungal surface. Besides this, we also confirmed that the extraradical mycelium (ERM) can actively take up Cr [either in the form of Cr(VI) or Cr(III)] and transport Cr [potentially in the form of Cr(III)-histidine analogues] to mycorrhizal roots but immobilize most of the Cr(III) in the fungal structures. Based on an X-ray absorption near-edge spectroscopy analysis of Cr(VI)-treated roots, we proposed that the intraradical fungal structures can also immobilize Cr within mycorrhizal roots. Our findings confirmed the immobilization of Cr by AMF, which plays an essential role in the Cr(VI) tolerance of AM symbioses.

Molecular characterization of microbial communities in the rhizosphere soils and roots of diseased and healthy Panax notoginseng.

Rhizosphere and root-associated microbial communities are known to be related to soil-borne disease and plant health. In the present study, the microbial communities in rhizosphere soils and roots of both healthy and diseased Panax notoginseng were analyzed by high-throughput sequencing of 16S rRNA for bacteria and 18S rRNA internal transcribed spacer for fungi, to reveal the relationship of microbial community structure with plant health status. In total, 5593 bacterial operational taxonomic units (OTUs) and 963 fungal OTUs were identified in rhizosphere soils, while 1794 bacterial and 314 fungal OTUs were identified from root samples respectively. Principal coordinate analysis separated the microbial communities both in the rhizosphere soils and roots of diseased P. notoginseng from healthy plants. Compared to those of healthy P. notoginseng, microbial communities in rhizosphere soils and roots of diseased plants showed a decrease in alpha diversity. By contrast, bacterial community dissimilarity increased and fungal community dissimilarity decreased in rhizosphere soils of diseased plants, while both bacterial and fungal community dissimilarity in roots showed no significant difference between healthy and diseased plants. Redundancy analysis at the phylum level showed that mycorrhizal colonization and soil texture significantly affected microbial community composition in rhizosphere soils, whereas shoot nutrition status had a significant effect on microbial community composition in root samples. Our study provided strong evidence for the hypothesis that microbial diversity could potentially serve as an indicator for disease outbreak of medicinal plants, and supported the ecological significance of microbial communities in maintaining plant healthy and soil fertility.

Arbuscular mycorrhizal symbiosis for sustainable cultivation of Chinese medicinal plants: a promising research direction.

Arbuscular mycorrhizal (AM) are symbiotic systems in nature and have great significance in promoting the growth and stress resistance of medicinal plants. During our literature search from the Chinese Scientific Information Database (Chinese National Knowledge Infrastructure, CNKI) we obtained 65 articles with "AM fungi" and "medicinal plant" as the key words, which indicates that in China, research efforts on these topics have been increasing. The main purposes of this review are to discuss the effects of mycorrhiza on the active ingredients of Chinese medicinal plants in comparison with results obtained in other plants in studies conducted by the international research community, and to introduce works published in Chinese journals to international colleagues.

Arbuscular mycorrhizal symbiosis and active ingredients of medicinal plants: current research status and prospectives.

Medicinal plants have been used world-wide for thousands of years and are widely recognized as having high healing but minor toxic side effects. The scarcity and increasing demand for medicinal plants and their products have promoted the development of artificial cultivation of medicinal plants. Currently, one of the prominent issues in medicinal cultivation systems is the unstable quality of the products. Arbuscular mycorrhiza (AM) affects secondary metabolism and the production of active ingredients of medicinal plants and thus influence the quality of herbal medicines. In this review, we have assembled, analyzed, and summarized the effects of AM symbioses on secondary metabolites of medicinal plants. We conclude that symbiosis of AM is conducive to favorable characteristics of medicinal plants, by improving the production and accumulation of important active ingredients of medicinal plants such as terpenes, phenols, and alkaloids, optimizing the composition of different active ingredients in medicinal plants and ultimately improving the quality of herbal materials. We are convinced that the AM symbiosis will benefit the cultivation of medicinal plants and improve the total yield and quality of herbal materials. Through this review, we hope to draw attention to the status and prospects of, and arouse more interest in, the research field of medicinal plants and mycorrhiza.

Amino acid influence on copper binding to peptides: cysteine versus arginine.

Matrix assisted laser desorption/ionization (MALDI) time-of-flight (TOF) mass spectrometry (MS) and theoretical calculations [density functional theory (DFT)] were utilized to investigate the influence of cysteine side chain on Cu(+) binding to peptides and how Cu(+) ions competitively interact with cysteine (-SH/SO(3)H) versus arginine. Results from theoretical and experimental (fragmentation reactions) studies on [M + Cu](+) and [M + 2Cu - H](+) ions suggest that cysteine side chains (-SH) and cysteic acid (-SO(3)H) are important Cu(+) ligands. For example, we show that Cu(+) ions are competitively coordinated to the -SH or SO(3)H groups; however, we also present evidence that the proton of the SH/SO(3)H group is mobile and can be transferred to the arginine guanidine group. For [M + 2Cu - H](+) ions, deprotonation of the -SH/SO(3)H group is energetically more favorable than that of the carboxyl group, and the resulting thiolate/sulfonate group plays an important role in the coordination structure of [M + 2Cu - H](+) ions, as well as the fragmentation patterns.