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Incorporating Metal-Ligand and Salt-Bridge Interactions in the Design of Protein Heterodimers. 结合金属配体和盐桥相互作用设计蛋白质异源二聚体。
IF 2.9 3区 生物学
Biochemistry Biochemistry Pub Date : 2025-07-11 DOI: 10.1021/acs.biochem.5c00108
Brian Maniaci, Matthew Mealka, Andrey A Bobkov, Boguslaw Stec, Tom Huxford, John J Love
{"title":"Incorporating Metal-Ligand and Salt-Bridge Interactions in the Design of Protein Heterodimers.","authors":"Brian Maniaci, Matthew Mealka, Andrey A Bobkov, Boguslaw Stec, Tom Huxford, John J Love","doi":"10.1021/acs.biochem.5c00108","DOIUrl":"https://doi.org/10.1021/acs.biochem.5c00108","url":null,"abstract":"<p><p>The design of chemically controlled asymmetric protein-protein interfaces will further enhance the building of precise protein-based biomaterials. Driving protein-protein interactions through engineered metal-ligand coordination and salt-bridge formation enables the reversible association of two unique binding partners. Creation of precise biomaterial is enhanced through the temporal and chemical control afforded by metal-controlled heterodimeric proteins. In addition, heterodimers enable the specific association of different passenger proteins expressed as fusions to the heterodimeric binding partners. To increase the versatility of protein-based tools, we converted a previously engineered metal-controlled homodimer into a metal-controlled heterodimer. To promote specificity of the heterodimer complex and prevent self-association, it was necessary to incorporate elements of positive and negative design, which was achieved through the incorporation of a cross-interface electrostatic interaction, as well as modifications to hydrophobic contacts at the protein-protein interface. The resulting metal-controlled heterodimer binds with low micromolar affinity, and the crystal structures indicate the presence of the designed dual-interaction motifs at the protein-protein interface.</p>","PeriodicalId":28,"journal":{"name":"Biochemistry Biochemistry","volume":" ","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-07-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144612039","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Collagen Biosynthesis and Its Molecular Ensemble: What Remains Unexplored. 胶原蛋白生物合成及其分子集合:仍未探索的领域。
IF 2.9 3区 生物学
Biochemistry Biochemistry Pub Date : 2025-07-10 DOI: 10.1021/acs.biochem.5c00261
Yoshihiro Ishikawa
{"title":"Collagen Biosynthesis and Its Molecular Ensemble: What Remains Unexplored.","authors":"Yoshihiro Ishikawa","doi":"10.1021/acs.biochem.5c00261","DOIUrl":"https://doi.org/10.1021/acs.biochem.5c00261","url":null,"abstract":"<p><p>Collagen embodies an intriguing paradox in protein biology. Despite being one of the most abundant protein superfamilies in vertebrates and having a seemingly simple structural organization, its biosynthesis is anything but straightforward. This apparent simplicity masks a complex and often contradictory biosynthetic landscape that poses significant challenges, particularly for newcomers to the field. Rather than following a linear or uniform pathway, collagen biosynthesis involves a coordinated series of tightly regulated steps, cotranslational post-translational modifications (PTMs), chain selection and registration, triple helix formation, and secretion, orchestrated by a specialized machinery, collectively termed the collagen molecular ensemble. This ensemble must overcome unconventional paradigms in protein biogenesis, rife with exceptions and unresolved questions. In this perspective, I examine underexplored aspects of the collagen biosynthetic machinery, spotlighting challenges in decoding the regulatory logic of PTMs, the spatial dynamics of trimer assembly, the functional consequences of chain registration, and the type-specific routes of secretion. By charting these uncertainties, I aim to challenge prevailing assumptions and invite interdisciplinary insight to help unravel the remaining mysteries of collagen biosynthesis.</p>","PeriodicalId":28,"journal":{"name":"Biochemistry Biochemistry","volume":" ","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144598900","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
β2-Adrenergic Receptor Utilizes Distinct Interaction Interfaces to Selectively form Heterooligomers with a Subset of Bitter Taste Receptors. β2-肾上腺素能受体利用不同的相互作用界面选择性地与一部分苦味受体形成异聚物。
IF 2.9 3区 生物学
Biochemistry Biochemistry Pub Date : 2025-07-09 DOI: 10.1021/acs.biochem.5c00208
Yuan-Yuan Peng, Yangwei Jiang, Yi-Sen Yang, Yan-Bo Xue, Shi-Meng Gong, Yue Zhang, Ruhong Zhou, Liquan Huang
{"title":"β2-Adrenergic Receptor Utilizes Distinct Interaction Interfaces to Selectively form Heterooligomers with a Subset of Bitter Taste Receptors.","authors":"Yuan-Yuan Peng, Yangwei Jiang, Yi-Sen Yang, Yan-Bo Xue, Shi-Meng Gong, Yue Zhang, Ruhong Zhou, Liquan Huang","doi":"10.1021/acs.biochem.5c00208","DOIUrl":"https://doi.org/10.1021/acs.biochem.5c00208","url":null,"abstract":"<p><p>G protein-coupled receptors (GPCRs) make up the largest receptor family in humans, which also constitute principal molecular targets for about 36% of approved drugs. Recent studies show that GPCRs can form heteromeric complexes with new molecular features. Little, however, is known about how human bitter taste receptors (T2Rs) form heteromeric receptors with other GPCRs. In this study, we combine biomolecular fluorescence complementation assays with methods for chemiluminescence imaging of cells, and find that β2-adrenergic receptor (β2AR) interacts with a subset of T2Rs, including T2R10, T2R14, T2R38, and T2R44, but selectively promotes cell membrane localization of only T2R14, T2R38, and T2R44. Furthermore, in silico modeling, coimmunoprecipitation, and immunofluorescence analysis indicate that β2AR utilizes distinct interfacial domains to interact with different T2Rs. And the β2AR-T2R14 interaction is selectively disrupted by a synthetic peptide corresponding to the transmembrane helix 4 of β2AR, which, however, does not block ligand-induced β2AR or T2R14 receptor internalization. Taken together, our findings demonstrate that β2AR employs different transmembrane helices to interact with and regulate special T2R subtypes. The insights obtained from this research may further our understanding of the β2AR-T2R interaction mechanisms and facilitate the development of new clinical drugs targeting β2AR-T2R complexes.</p>","PeriodicalId":28,"journal":{"name":"Biochemistry Biochemistry","volume":" ","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-07-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144590050","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Correction to "Exploring Bioactive Fungal RiPPs: Advances, Challenges, and Future Prospects". 对“探索生物活性真菌ripp:进展、挑战和未来前景”的更正。
IF 2.9 3区 生物学
Biochemistry Biochemistry Pub Date : 2025-07-09 DOI: 10.1021/acs.biochem.5c00383
Qiuyue Nie, Chunxiao Sun, Shuai Liu, Xue Gao
{"title":"Correction to \"Exploring Bioactive Fungal RiPPs: Advances, Challenges, and Future Prospects\".","authors":"Qiuyue Nie, Chunxiao Sun, Shuai Liu, Xue Gao","doi":"10.1021/acs.biochem.5c00383","DOIUrl":"https://doi.org/10.1021/acs.biochem.5c00383","url":null,"abstract":"","PeriodicalId":28,"journal":{"name":"Biochemistry Biochemistry","volume":" ","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-07-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144598901","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Pseudomonas aeruginosa Cryptic Prophage Endolysin Is a Highly Active Muramidase. 铜绿假单胞菌隐前噬菌体内溶素是一种高活性的酶。
IF 2.9 3区 生物学
Biochemistry Biochemistry Pub Date : 2025-07-09 DOI: 10.1021/acs.biochem.5c00142
Per Kristian Thorén Edvardsen, Andrea Nikoline Englund, Åsmund Kjendseth Ro̷hr, Stéphane Mesnage, Gustav Vaaje-Kolstad
{"title":"<i>Pseudomonas aeruginosa</i> Cryptic Prophage Endolysin Is a Highly Active Muramidase.","authors":"Per Kristian Thorén Edvardsen, Andrea Nikoline Englund, Åsmund Kjendseth Ro̷hr, Stéphane Mesnage, Gustav Vaaje-Kolstad","doi":"10.1021/acs.biochem.5c00142","DOIUrl":"https://doi.org/10.1021/acs.biochem.5c00142","url":null,"abstract":"<p><p>Endolysins are phage-encoded enzymes that cleave the peptidoglycan of host bacteria. These enzymes have gained considerable attention due to their ability to cause cell lysis, making them candidates as antibacterial agents. Most <i><i>Pseudomonas aeruginosa</i></i> genomes, including the common laboratory strains PAO1 and UCBPP-PA14, contain a cryptic prophage encoding a glycoside hydrolase family 19 endolysin (named <i>Pa</i>GH19Lys in the present study). Family 19 glycoside hydrolases are known to target peptidoglycan and chitin-type substrates. <i>Pa</i>GH19Lys was not active toward chitin but exhibited activity toward chloroform-treated Gram-negative bacteria, displaying ∼10,000-fold higher activity than hen egg white lysozyme. Analysis of products derived from <i>Pa</i>GH19Lys activity toward purified <i><i>P. aeruginosa</i></i> peptidoglycan showed that the enzyme catalyzed hydrolysis of the β-1,4 linkage between <i>N-</i>acetylmuramic acid and <i>N-</i>acetyl-d-glucosamine, classifying the enzyme as a muramidase. Finally, the crystal structure of <i>Pa</i>GH19Lys was determined and solved to 1.8 Å resolution. The structure of the enzyme showed a globular α-helical fold possessing a deep but relatively open catalytic cleft.</p>","PeriodicalId":28,"journal":{"name":"Biochemistry Biochemistry","volume":" ","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-07-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144590047","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Structural Insights into the GABARAP-ATG3 Backside Interaction and Apo ATG3 Conformation. GABARAP-ATG3背面相互作用和Apo ATG3构象的结构研究。
IF 2.9 3区 生物学
Biochemistry Biochemistry Pub Date : 2025-07-08 DOI: 10.1021/acs.biochem.4c00485
Kazuto Ohashi, Gerard J Kroon, Takanori Otomo
{"title":"Structural Insights into the GABARAP-ATG3 Backside Interaction and Apo ATG3 Conformation.","authors":"Kazuto Ohashi, Gerard J Kroon, Takanori Otomo","doi":"10.1021/acs.biochem.4c00485","DOIUrl":"https://doi.org/10.1021/acs.biochem.4c00485","url":null,"abstract":"<p><p>Members of the ATG8 family of ubiquitin-like proteins (Ubls) are covalently attached to phosphatidylethanolamine (PE) on nascent autophagosomal membranes, where they recruit cargo receptors and promote membrane expansion. Although the overall lipidation pathway is well established, the molecular details-particularly those involving the E2 enzyme ATG3-remain incompletely defined. Here, we uncover a previously unrecognized, noncovalent binding mode between the mammalian ATG8 protein GABARAP and the backside of ATG3's catalytic E2 domain. In crystals, an isopeptide-linked GABARAP∼ATG3 conjugate self-assembles into a helical filament via this backside interface, mirroring architectures observed for canonical Ub/Ubl∼E2 conjugates. The E2 backside-binding surface on GABARAP is topologically distinct from those of other Ub/Ubl proteins and overlaps the LC3-interacting region (LIR) motif-binding site. Solution NMR confirms this interaction, and targeted mutagenesis shows that disrupting the interface impairs PE conjugation. Complementary NMR and AlphaFold modeling of apo ATG3 reveal an intramolecular contact between a segment of its flexible region (FR) and the catalytic core that suppresses conjugation. Together, these findings establish backside engagement as a critical feature of ATG8 lipidation and illuminate the dynamic architecture and regulation of ATG3.</p>","PeriodicalId":28,"journal":{"name":"Biochemistry Biochemistry","volume":" ","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-07-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144590049","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Enhanced G-Quadruplex Stability and Anticancer Activity of N2-Aryl Deoxyguanosine-Modified T40214 Oligonucleotides Targeting STAT3 in Prostate Cancer. n2 -芳基脱氧鸟苷修饰的靶向STAT3的T40214寡核苷酸在前列腺癌中增强g -四重体稳定性和抗癌活性
IF 2.9 3区 生物学
Biochemistry Biochemistry Pub Date : 2025-07-08 DOI: 10.1021/acs.biochem.5c00158
Nishant Kumar Choudhary, Swrajit Nath Sharma, Gourav Das, Atanu Ghosh, Siddharam Shivappa Bagale, Surajit Sinha, Kiran R Gore
{"title":"Enhanced G-Quadruplex Stability and Anticancer Activity of <i>N</i><sup>2</sup>-Aryl Deoxyguanosine-Modified T40214 Oligonucleotides Targeting STAT3 in Prostate Cancer.","authors":"Nishant Kumar Choudhary, Swrajit Nath Sharma, Gourav Das, Atanu Ghosh, Siddharam Shivappa Bagale, Surajit Sinha, Kiran R Gore","doi":"10.1021/acs.biochem.5c00158","DOIUrl":"https://doi.org/10.1021/acs.biochem.5c00158","url":null,"abstract":"<p><p>Signal transducer and activator of transcription 3 (Stat3) is a key molecular target in many cancers due to its role in tumor cell proliferation and survival. T40214, a G-quadruplex (G4) forming oligonucleotide, targets the Stat3 dimer and inhibits its DNA binding activity. In this study, we introduced <i>N</i><sup>2</sup>-furfuryl and <i>N</i><sup>2</sup>-cinnamyl deoxyguanosine modifications at the G-tetrad positions in T40214 to assess their structural and antitumor effects in prostate cancer cells. A single <i>N</i><sup>2</sup>-furfuryl/cinnamyl modification preserved the stable parallel G4 conformation. Incorporating either of these modifications into the top G-quartet (TF15 and TC15) significantly enhanced thermal stability. Molecular dynamics simulation studies revealed that the aryl moieties were well accommodated at the 5'-ends without disrupting the interaction with Stat3. It is also evident that H-bonding and π-π stacking interactions induced due to the presence of the aryl moieties contributed to the improved thermal stabilities for TF15 and TC15, respectively. Gel mobility assays confirmed that all aryl-modified T40214 G4s form stable 5'-5' dimers, similar to native T40214. TF15 and TC15 derivatives exhibited potent antiproliferative activity (IC<sub>50</sub> = 0.37-0.39 μM) and effectively induced apoptosis while suppressing the Stat3-mediated gene expressions in DU145 cells. Overall, these findings demonstrate the potential of these aryl modifications in T40214 as a promising Stat3-targeting therapeutic approach for prostate cancers.</p>","PeriodicalId":28,"journal":{"name":"Biochemistry Biochemistry","volume":" ","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-07-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144590048","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Mapping the Conformational Heterogeneity Intrinsic to the Protein Native Ensemble. 绘制蛋白质天然集合的构象异质性。
IF 2.9 3区 生物学
Biochemistry Biochemistry Pub Date : 2025-07-04 DOI: 10.1021/acs.biochem.5c00201
Adithi Kannan, Athi N Naganathan
{"title":"Mapping the Conformational Heterogeneity Intrinsic to the Protein Native Ensemble.","authors":"Adithi Kannan, Athi N Naganathan","doi":"10.1021/acs.biochem.5c00201","DOIUrl":"https://doi.org/10.1021/acs.biochem.5c00201","url":null,"abstract":"<p><p>In the AlphaFold era, there is a significant momentum in predicting protein structures, functionality, and mutational hotspots from deep learning approaches. In this review, we highlight how structural information is only a starting point in understanding function and why a single structure for a given sequence rarely captures the true picture. We provide an overview of selected experimental and computational techniques that can be employed to delineate the conformational landscapes of proteins at different levels of resolution. An integrative approach has often led to the identification of considerable heterogeneity in the native ensemble, with high-resolution methods revealing proportionately larger complexity. Partial structure in the native ensemble appears to be the norm, which typically appears as excited or intermediate states in the folding conformational landscape. A more nuanced approach mapping the ensemble of states, their relative populations, associated time scale of interconversion, and their sensitivity to different physical perturbations is therefore necessary. Thus, \"sequence-ensemble-function\" paradigm is the way forward even for apparently well-folded proteins, with multiprobe experiments and physically grounded models providing an intimate and intuitive understanding of this connection.</p>","PeriodicalId":28,"journal":{"name":"Biochemistry Biochemistry","volume":" ","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-07-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144564157","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
CRDSAT under Heat: Balancing Stability, Affinity, and Functional Utility of Computationally Designed Tag Variants. 热下的CRDSAT:计算设计标签变体的平衡稳定性、亲和力和功能效用。
IF 2.9 3区 生物学
Biochemistry Biochemistry Pub Date : 2025-07-03 DOI: 10.1021/acs.biochem.5c00128
Esteban Guiot, Marie-Eve Chagot, Alexis Boutilliat, Pascal Reboul, Alexandre Kriznik, Marc Quinternet
{"title":"CRD<sub>SAT</sub> under Heat: Balancing Stability, Affinity, and Functional Utility of Computationally Designed Tag Variants.","authors":"Esteban Guiot, Marie-Eve Chagot, Alexis Boutilliat, Pascal Reboul, Alexandre Kriznik, Marc Quinternet","doi":"10.1021/acs.biochem.5c00128","DOIUrl":"10.1021/acs.biochem.5c00128","url":null,"abstract":"<p><p>In general, the easier and cheaper the expression and purification processes are, the more profitable the production of a recombinant protein of interest is, especially in the industrial world. Previously, we have developed the lectinic CRD<sub>SAT</sub> tag that we demonstrated is efficient at cost-effectively purifying passenger proteins. It also has the advantage of being quite small and limiting steric hindrance upon release by protease cleavage. Here, we used protein sequence optimization to design highly thermostable versions of CRD<sub>SAT</sub> and showed that the midpoint denaturation temperature could be increased from 55.8 to 92.2 °C. In fact, our variants (called CRD<sub>VLs</sub>) possess the ability to support a heating step during the purification process, which represents an easy way to eliminate thermolabile proteins coming from the host cells when the recombinant proteins are produced in bacteria. To challenge our CRD<sub>VLs</sub>, we fused them to a PET hydrolase exhibiting promising industrial activity at 70 °C and showed that CRD<sub>VL</sub>-tagged enzymes remain active, even after heating, with a balancing effect due to the CRD<sub>VL</sub> internal mutations. Surprisingly, whereas mutations in CRD<sub>VLs</sub> were introduced far from the d-lactose binding site, we also showed that the affinity toward the disaccharide was clearly improved in the variants to reach a dissociation constant (<i>K</i><sub>d</sub>) of around 30 μM (the <i>K</i><sub>d</sub> of the CRD<sub>SAT</sub> being measured at around 90 μM), paving the way for the use of our tag in applications such as lectin-based affinity enrichment or those requiring few, cheap, and simple purification steps.</p>","PeriodicalId":28,"journal":{"name":"Biochemistry Biochemistry","volume":" ","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144558421","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
MA'AT Analysis of Peptides: Conformational Equilibrium of Alanine Dipeptide in Aqueous Solution. 多肽的MA'AT分析:丙氨酸二肽在水溶液中的构象平衡。
IF 2.9 3区 生物学
Biochemistry Biochemistry Pub Date : 2025-07-02 DOI: 10.1021/acs.biochem.5c00117
Jieye Lin, Reagan J Meredith, Mi-Kyung Yoon, Ian Carmichael, Anthony S Serianni
{"title":"<i>MA'AT</i> Analysis of Peptides: Conformational Equilibrium of Alanine Dipeptide in Aqueous Solution.","authors":"Jieye Lin, Reagan J Meredith, Mi-Kyung Yoon, Ian Carmichael, Anthony S Serianni","doi":"10.1021/acs.biochem.5c00117","DOIUrl":"https://doi.org/10.1021/acs.biochem.5c00117","url":null,"abstract":"<p><p>The conformational properties of alanine dipeptide (<b>1</b>) have been widely investigated by molecular dynamics (MD) and quantum mechanics calculations. Nine idealized conformers have been identified (α<sub>L</sub>, α<sub>D</sub>, C<sub>7</sub><sup>ax</sup>, β<sub>2</sub>, C<sub>5</sub>, α', C<sub>7</sub><sup>eq</sup>, P<sub>II</sub>, and α<sub>R</sub>), distinguished by their preferred backbone torsion angles φ (C<sub>car</sub>-N-C<sub>α</sub>-C<sub>car</sub>) and ψ (N-C<sub>α</sub>-C<sub>car</sub>-N). The relative energies of these conformers differ depending on the force fields or the level of theory used in the calculations. <i>MA'AT</i> analysis has been applied to give experiment-based probability distributions of φ and ψ in <b>1</b> in an aqueous solution for comparison to those obtained by aqueous MD. Using <sup>13</sup>C- and <sup>15</sup>N-labeled isotopomers of <b>1</b>, 11 redundant NMR <i>J</i>-couplings that depend primarily on either φ or ψ were measured from 1D and 2D NMR spectra. Density functional theory calculations were conducted to obtain potential energy surface (PES) plots, and φ- and ψ-dependent <i>J</i>-couplings were calculated as a function of both angles. Parameterized <i>J</i>-coupling equations were used in conjunction with experimental <i>J</i>-values in <i>MA'AT</i> analysis to give a reproducible average unimodal model of φ (298.8° and 43.8°; mean and circular standard deviation) and a tentative bimodal model of ψ (mean values of 192° ± 32° and 318° ± 22° (mean ± STD); both states are approximately equally populated). The experimental <i>J</i>-couplings indicate highly favored <i>trans</i> configurations of both amide bonds in <b>1</b>. These findings support an experiment-based conformational model of <b>1</b> in aqueous solution involving α<sub>R</sub> ⇌ P<sub>II</sub> exchange, which is qualitatively consistent with PES and MD data.</p>","PeriodicalId":28,"journal":{"name":"Biochemistry Biochemistry","volume":" ","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-07-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144537394","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
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