Changes In Protein Secondary Structure Research Articles

Novel insights into fouling mechanisms in anaerobic acidification membrane bioreactor: The leading role of pH value

Anaerobic acidification membrane bioreactors (AAMBRs) have recently emerged as effective systems for recovering volatile fatty acids (VFAs) from municipal wastewater. However, membrane fouling remains a critical challenge, with its underlying mechanisms not yet fully understood. Given its importance in inhibiting methanogenic bacteria and stabilizing VFAs production, this study explores the direct and indirect effects of pH on membrane fouling mechanisms in AAMBRs. The results demonstrated that compared to pH 7, the fouling potential of anaerobic sludge was significantly higher at pH levels of 5 and 10 owing to a decrease of sludge floc size and an increase of soluble microbial products (SMP) especially proteins. Analytical techniques such as confocal laser scanning microscopy (CLSM), fourier transform infrared spectroscopy (FTIR), and fluorescence excitation-emission matrix (F-EEM) analyses revealed a substantial increase in organic foulants particularly proteins on the membrane surface at pH levels of 5 and 10. Circular dichroism (CD) spectroscopy further indicated a significant change in protein secondary structure, specifically an increase in α-helix content under extreme pH conditions. Furthermore, the extended Derjaguin-Landau-Verwey-Overbeek (XDLVO) theory indicated that elevated protein concentrations enhance the adhesion of sludge and SMP to membrane surfaces. Insights from the Flory-Huggins theory demonstrated that variations in protein structure significantly contribute to increased filtration resistance within the gel layer. Both experimental data and theoretical models underscore the dual role of pH in optimizing VFAs production and managing membrane fouling, offering insights for enhancing AAMBR performance and mitigating fouling issues.

Interactions with peanut protein isolate regulate the bioaccessibility of cyanidin-3-O-glucoside: Multispectral analysis, simulated digestion, and molecular dynamic simulation

Anthocyanins are susceptible to degradation owing to environmental factors. Combining them with proteins can improve their stability; however, the interaction mechanism is difficult to elucidate. This study used multispectral and molecular dynamics simulations and molecular docking methods to investigate the interaction mechanism between peanut protein isolate (PPI) and cyanidin-3-O-glucoside (C3G). The UV absorption peak and PPI turbidity increased, while the fluorescence intensity decreased with greater C3G content. Protein secondary structure changes suggested that PPI and C3G coexisted in spontaneous covalent and non-covalent interactions via static quenching. The complex structures were stable over time and C3G stably bound to the peanut globulin Ara h 3 cavity through hydrogen bonding and hydrophobic interactions. Furthermore, PPI enhanced the C3G antioxidant activity and bioaccessibility by increasing its retention rate during in-vitro simulated digestion. This study elucidates the binding mechanism of PPI and C3G and provides insight into applications of the complex in food development.

Effect of different thermal processing methods and thermal core temperatures on the protein structure and in vitro digestive characteristics of beef

This study aimed to investigate the effect of different thermal processing treatments on the protein digestion characteristics of beef. The beef samples were subjected to different cooking methods, namely steaming, boiling, and roasting, and different core temperatures (75 °C, 80 °C, 85 °C, and 90 °C), and were subjected to in vitro gastrointestinal digestion simulation. All the thermal processing treatments increased the protein digestibility; the samples that were steamed at 85 °C (S85), boiled at 80 °C (B80), and roasted at 80 °C (R80) showed the biggest gains. The S85 released more peptide species after gastrointestinal digestion, according to peptididomic studies. These differences were closely related to protein structure. Thermal processing treatments resulted in a higher degree of proteolysis and looser protein conformation, as evidenced by decreased intrinsic fluorescence and electrophoretic band intensity, increased surface hydrophobicity, and the change in protein secondary structure from α-helix to β-sheet and random coil. Based on the results, S85 was identified as the optimal thermal processing treatment for enhancing the digestibility of beef protein. The results provide valuable insights into the nutritional qualities and digestion of heat-processed beef protein.

CHANGES IN SECONDARY STRUCTURE OF PROTEIN IN SKELETAL MUSCLE DUE TO HIGH-CARBOHYDRATE OR HIGH-FAT DIETS

Objective: Obesity, which arises from changes in lifestyle and feeding habits, is a threat to human health. One essential contributor to the increase in obesity rates is the popularity of high-calorie diets. This study aims to investigate high-fat (HFD) and high-carbohydrate (HCD) diet-induced molecular changes in protein secondary structure in longissimus dorsi skeletal muscle tissues of female inbred C57BL/6J mice by utilizing Attenuated Total Reflectance-Fourier Transform Infrared (ATR-FTIR) spectroscopy. Materials and Methods: Mice were fed a control diet, HCD, or HFD for 24 weeks. Their skeletal muscle tissues were collected, and their spectra were recorded using a Bruker Invenio S ATR-FTIR spectrometer in the 4000-400 cm-1 region. Results: The protein secondary structure profiles of the HCD group demonstrated a significant rise in antiparallel β-sheet and β-turn and a decline in parallel β-sheets together with the insignificant increase in aggregated β-sheets and a decrease in α-helix. The impact of an HFD on protein conformation is less pronounced than HCD. The HFD diet led to an increase in antiparallel β-sheets and a decrease in parallel β-sheets. Although it was not significant, an increase was observed in β-turn and α-helix. Conclusion: These results propose the appearance of protein aggregation and/or formation of protein-protein intermolecular interaction in skeletal muscle tissues of female inbred C57BL/6J mice. Collectively, these data suggest that both high-calorie diets impair secondary structures of protein in skeletal muscle that may affect its metabolic function.

Bio-spectroscopic analysis of corneal structural alterations in dry eye disease: A study of collagen, co-enzymes, lipids, and proteins with emphasis on phytotherapy intervention

Dry eye disease (DED) stands as a prevalent cause for ophthalmology consultations, securing the third position following refractive errors and cataracts. Moreover, the likelihood of experiencing DED escalates with advancing age. In this experimental study corneal tissue alterations due to DED were investigated over different periods by applying both infrared and synchronous fluorescence spectroscopy. The potential effects of instillation of pomegranate and green tea water extracts as green-friendly treatment modalities were also evaluated. The obtained results collectively indicate that DED affects the OH bearing constituents (collagen, glycosaminoglycans, and proteoglycans) of cornea leading to changes in protein secondary structure and the collagen fibrils. Additionally, enhanced dehydrated environment, and reduced energetic/metabolic state, as indicated by co-enzymes, was observed. Phyto-therapeutic administration can contain these alterations with enhanced energetic/metabolic state and increased hydration environment. In conclusion, instillation of green tea extract can protect/restore the collagen fibrils and its potential effects, in general, exceeds that of pomegranate extract.

UPC2 mutations and development of azole resistance in Candida albicans hospital isolates from Lebanon

ObjectivesThis study evaluated the role of Upc2 in the development of azole resistance in Candida albicans isolates from Lebanese hospitalized patients and determined a correlation between resistance and virulence. MethodsThe UPC2 gene which codes for an ergosterol biosynthesis regulator was sequenced and analysed in two azole-resistant and one azole-susceptible C. albicans isolates. An amino acid substitution screening was carried out on Upc2 with a focus on its ligand binding domain (LBD) known to interact with ergosterol. Then, Upc2 protein secondary structure prediction and homology modelling were conducted, followed by total plasma membrane ergosterol and cell wall chitin quantifications. For virulence, mouse models of systemic infection were generated and an agar adhesion and invasion test was performed. ResultsAzole-resistant isolates harboured novel amino acid substitutions in the LBD of Upc2 and changes in protein secondary structures were observed. In addition, these isolates exhibited a significant increase in plasma membrane ergosterol content. Resistance and virulence were inversely correlated while increased cell wall chitin concentration does not seem to be linked to resistance since even though we observed an increase in chitin concentration, it was not statistically significant. ConclusionsThe azole-resistant C. albicans isolates harboured novel amino acid substitutions in the LBD of Upc2 which are speculated to induce an increase in plasma membrane ergosterol content, preventing the binding of azoles to their target, resulting in resistance.

Effect of temperature and sodium bicarbonate combined on aggregation, rheology and conformation of low-salt chicken myofibrillar protein

To study the impact of temperature (4–50 °C) and sodium bicarbonate (0.4%) on the solubility, protein aggregation and conformation of low-salt (1 mmol/L sodium chloride) chicken myofibrillar protein, the changes in turbidity, particle size, protein secondary and tertiary structures were investigated. There was no significant difference in pH when it did not exceed 30 °C, then a significant increase (p < 0.05) when it was above 30 °C. The solubility, total and reactive sulfhydryl groups, and apparent viscosity increased first and then decreased (p < 0.05), and reached the maximum values at 30 °C; whereas the turbidity, particle size, α-helix, and random coil contents showed opposite trends. Additionally, the fluorescence peak experienced a noticeable redshift with rising temperatures; β-turn content significantly increased but β-sheet content decreased significantly. Finally, combining sodium bicarbonate with a temperature of around 30 °C could enhance chicken myofibrillar protein solubility and change the protein structure under a low-salt condition.

Insights into the starch and proteins molecular structure changes of foxtail millet sourdough: Effect of fermentation from grains of cereal to pre-meal

This study investigated the effects of foxtail millet sourdough fermentation time (0, 8, 16, and 24 h) on the protein structural properties, thermomechanical, fermentation, dynamic rheological, starch granules crystalline regions molecular mobility, and starch microstructural characteristics. The fermentation led to a significant increase in the concentration of free amino acids from protein hydrolysis. Fourier transform infrared spectroscopy (FTIR) revealed changes in protein secondary structure and the presence of functional groups of different bioactive compounds. The result of thermomechanical properties showed a significant increase in the stability (0.70–0.79 min) and anti-retrogradation ability (2.29–3.14 Nm) of lactic acid bacteria (LAB) sourdough compared to the control dough, showing a wider processing applicability with radar profiler index. In contrast, sourdoughs with lower tan δ values had higher elasticity and strength. Scanning electron microscopy showed that the surface of the starch appeared from smooth to uneven with patchy shapes and cavities, which declined the crystallinity from 34.00 % to 21.57 %, 23.64 %, 25.09 %, and 26.34 % respectively. Fermentation changed the To, Tp, Tc, and ΔH of the starch. The results of the study will have great potential for application in the whole grain sourdough industry.

Raman spectroscopy in the study of amyloid formation and phase separation.

Neurodegenerative diseases, such as Alzheimer's and Parkinson's, share a common pathological feature of amyloid structure accumulation. However, the structure-function relationship between these well-ordered, β-sheet-rich, filamentous protein deposits and disease etiology remains to be defined. Recently, an emerging hypothesis has linked phase separation, a process involved in the formation of protein condensates, to amyloid formation, suggesting that liquid protein droplets serve as loci for amyloid initiation. To elucidate how these processes contribute to disease progression, tools that can directly report on protein secondary structural changes are needed. Here, we review recent studies that have demonstrated Raman spectroscopy as a powerful vibrational technique for interrogating amyloid structures; one that offers sensitivity from the global secondary structural level to specific residues. This probe-free technique is further enhanced via coupling to a microscope, which affords structural data with spatial resolution, known as Raman spectral imaging (RSI). In vitro and in cellulo applications of RSI are discussed, highlighting studies of protein droplet aging, cellular internalization of fibrils, and Raman imaging of intracellular water. Collectively, utilization of the myriad Raman spectroscopic methods will contribute to a deeper understanding of protein conformational dynamics in the complex cellular milieu and offer potential clinical diagnostic capabilities for protein misfolding and aggregation processes in disease states.

Synthesis of hydroxyethyl starch 200/0.5-loaded albumin nanoparticles: biocompatibility and interaction mechanism.

We aimed to synthesize hydroxyethyl starch (HES) 200/0.5-loaded bovine serum albumin nanoparticles (HBNs) and investigate the compatibility and binding mechanism in simulated physiological environments. Here, to elucidate the morphology, biocompatibility, and formation mechanism of HBNs, techniques such as scanning electron microscopy, haemolysis test, fluorescence, and circular dichroism spectroscopy were applied. The thermodynamic parameters at body temperature (ΔS° = -26.7J·mol-1 ·K-1 , ΔH° = -3.20 × 104 J·mol-1 , and ΔG = -2.35 × 104 J·mol-1 ) showed a 1:1 binding stoichiometry, which was formed by hydrogen bonds and van der Waals interactions. In addition, the conformational analysis showed that the microenvironment of fluorophores was altered with the adaptational protein secondary structural changes. Energy transfer occurred from the fluorophores to HES with a high possibility. All these results provided accurate and complete primary data for demonstrating the interaction mechanisms of HES with BSA, which helps to understand its pharmaceutical effects in blood.

Molecular Evidence of Structural Changes in Silk Using Unlimited Degradation Mass Spectrometry.

Proteomics has important uses in archeological science because it can distinguish species, reveal the evolution of paleontology, and provide biological evidence of historical events. However, this technique still has full potential in the study of silk aging mechanisms. In this work, we propose a strategy combining unlimited degradation with mass-spectrometry-based proteomics techniques, which interpret protein fragmentation propensity and secondary structure changes by detecting content changes of specific peptide groups in complex proteomes. This approach was employed to study the conformational changes in silk microscopic crystals after heat treatment. Combining conventional mechanics and crystallographic characterization, a thermal aging degradation mechanism model was proposed. At the same time, it explained the interesting problem that the crystallinity remained unchanged, but the mechanical properties decreased significantly. Focusing on the unlimited degradation process, this method will be widely applicable to the study of silk and wool aging processes and regenerated silk fibroin.

Effects of different ohmic heating treatments on parvalbumin structure and reduction of allergenicity in Japanese eel (Anguilla japonica)

We investigated the effects of ohmic heating (OH) on the structural properties and allergenicity of parvalbumin (PV). Compared to other heating methods (water bath heating (WH), OH combined with WH, and OH combined with air thermostatic heating (AH)), pure OH heating expended the least time and total energy. PV sensitization was reduced by approximately 65% by pure OH heating. SDS-PAGE, tricine–SDS-PAGE, and western blotting analyses revealed a molecular weight of sensitized β-PV of about 12 kDa. Band intensity decreased with increasing OH time, and significant changes were observed in amino acid content, secondary structure, microstructure, and dielectric properties. Reducing PV, allergenicity through protein unfolding and secondary structural changes, thereby possibly reducing the allergenicity of eel, provides a theoretical basis for developing hypoallergenic products.

Effects of chickpea protein-stabilized Pickering emulsion on the structure and gelling properties of hairtail fish myosin gel.

The effects of different amount (0-12%) of chickpea protein-stabilized Pickering emulsion (CPE) on the gelling properties, intermolecular interactions, microstructure, and physicochemical stability of hairtail fish myosin gels were investigated. The myosin gel with 6%-9% CPE demonstrated significantly higher viscoelasticity, gel strength, hardness, water-holding capacity and whiteness, compared to the control (P<0.05). In addition, Raman spectroscopy showed that CPE changed the microenvironment of the myosin, which promoted the changes in protein secondary structures, disulfide bond conformation and the local environments of the composite gels. The addition of 6%-9% CPE also enhanced the disulfide bond and hydrophobic interaction of myosin gels which induced more compact gel network structures. Furthermore, CPE improved the lipid oxidative stability and freeze-thaw stability of myosin gel. The results indicated that CPE could improve the gelling properties of myosin, making it a potential new additive and lipid substitute for the development of new emulsion gel products.

Variations in the Protein Hydration and Hydrogen-Bond Network of Water Molecules Induced by the Changes in the Secondary Structures of Proteins Studied through Near-Infrared Spectroscopy.

This study investigated how the secondary structural changes of proteins in aqueous solutions affect their hydration and the hydrogen-bond network of water molecules using near-infrared (NIR) spectroscopy. The aqueous solutions of three types of proteins, i.e., ovalbumin, β-lactoglobulin, and bovine serum albumin, were denatured by heating, and changes in the NIR bands of water reflecting the states of hydrogen bonds induced via protein secondary structural changes were investigated. On heating, the intermolecular hydrogen bonds between water molecules as well as between water and protein molecules were broken, and protein molecules were no longer strongly bound by the surrounding water molecules. Consequently, the denaturation was observed to proceed depending on the thermodynamic properties of the proteins. When the aqueous solutions of proteins were cooled after denaturation, the hydrogen-bond network was reformed. However, the state of protein hydration was changed owing to the secondary structural changes of proteins, and the variation patterns were different depending on the protein species. These changes in protein hydration may be derived from the differences in the surface charges of proteins. The elucidation of the mechanism of protein hydration and the formation of the hydrogen-bond network of water molecules will afford a comprehensive understanding of the protein functioning and dysfunctioning derived from the structural changes in proteins.

Extraction and modification of protein from sesame oil cake by the application of emerging technologies

Present work evaluated the extraction yield and quality of protein from defatted sesame meal (DSM) using ultrasound-assisted extraction (UAE), low-temperature microwave-assisted extraction (MAE), and moderate electric field-assisted extraction (MEFAE). It was observed that the application of emerging technologies as pre-treatments significantly increased protein yield from 26.4% (without pre-treatments) to 38.9% (with UAE 450 W–20 min), 36.05% for MAE (with 500 W–20 min) and 32.75% for MEFAE (with 100 V–30 min) and improved the functional properties of Sesame protein isolate (SPI). FTIR revealed Amide I to III bands in SPI, with characteristic changes in protein secondary structure. The treated sample showed higher thermal stability evident from the denaturation temperature increase from 203.41 to 221.40 °C. The protein's microstructure in this study was transformed using various extraction techniques into a compact structure with a wrinkled surface. MAE-SPI showed maximum Invitro protein digestibility as 94.44%. The molecular weight profile revealed that the SPI samples' protein bands had molecular weights between 6.5 and 200 kDa. SDS-PAGE results revealed a change in the intensity of protein bands, and all of the main allergen protein bands were degraded.

Lutein fortification of wheat bread with marigold powder: Impact on rheology, water dynamics, and structure.

Demands for foods conducive to eye health have been on the increase in the global healthcare sector. Marigold powder as a major source of lutein was utilized to produce lutein-fortified breads for ocular health. The physicochemical characteristics of the doughs and breads were investigated in terms of rheology, water mobility, and protein secondary structures. The incorporation of marigold powder decreased the water absorption of doughs without significantly altering thermo-mechanical properties. With a range of fortification levels (1 ~ 3%), marigold powder led to decreased storage and loss modulus of doughs by weakening their gluten network, which was supported by their T2 relaxation times. The resistances of the doughs weakened with increasing levels of marigold powder, while their extensibilities significantly incremented. FTIR spectral deconvolution revealed the changes of wheat protein structures upon marigold powder incorporation, in which the proportion of β-turn increased at the expense of β-sheet ratio. The breads with marigold powder displayed increased specific volume from 4.034 to 4.368 mL/g, accompanied by softer textures. The baking process led to heat-induced losses in lutein concentration of less than 10% within the crumbs and approximately 30% in the crusts. The use of marigold powder induced changes in protein secondary structure and extensional features of doughs, contributing to increased loaf volume and softer texture. Overall, this study provides fundamental information about the rheological and structural effects of marigold powder in a wheat bread system, consequently encouraging the food industry to utilize marigold power as a functional food ingredient. This article is protected by copyright. All rights reserved.

Abstract 5561: Molecular imaging of calcification and soft tissue defines prognosis of DCIS to invasive breast cancer

Abstract Introduction: Ductal carcinoma in situ (DCIS) is a non-obligatory precursor to invasive breast cancer (IBC). Currently there are no reliable markers to indicate if DCIS will progress IBC after an initial treatment, or if it will remain as DCIS. Because of this uncertainty, standard treatment for DCIS includes surgery with or without radiotherapy. Breast microcalcifications are a common feature in the mammographic detection of DCIS and occur in around 80% of DCIS and 50% of IBC. Despite this, their potential role in the development of DCIS and with progression to IBC remains largely unexplored. The main aim of the study is to identify novel biomarkers for DCIS prognosis, based on chemical and molecular compositional changes of calcifications and their surrounding soft tissue in DCIS. Methods: Consecutive tissue section from 422 patients were analyzed using mid-infrared and Raman hyperspectral imaging and X-ray diffraction (XRD) and included (i) ‘DCIS controls’ (DCIS without recurrence) (n=193), (ii) ‘DCIS cases’ (DCIS which subsequently recurred as an invasive disease) (n=123), (iii) ‘synchronous DCIS with invasive cancer’ (n=44) and ‘benign’ (n=62) groups. Both parametrized and data mining approaches including cluster analysis, unsupervised and supervised multivariate statistical analysis and biomodelling based on leave-one-sample-out cross-validation were used to classify the data and develop DCIS prediction models. Results: Prediction modelling of 314 calcification and soft tissue spectral images from 170 patients (‘DCIS controls’=118 versus ‘DCIS cases’=52) showed an AUROC mean value of 0.85 in distinguishing DCIS that did not recur from DCIS that recurred as IBC. Prediction modelling of XRD data from 124 patients (‘DCIS controls’=67 versus ‘DCIS cases’=57) showed an AUROC mean value of 0.80. The calcification spectral features showed pathology specific changes in phosphate to carbonate ratio as well as changes in magnesium whitlockite content. The epithelial features showed changes in protein secondary structure and content indicating structural remodeling between the two groups. XRD parametrized data analysis corroborated these observations in terms of difference in whitlockite, as well as crystallinity/unit axis of the measured calcifications. The prediction models are currently being tested independently on the remaining sample data. Conclusion: Complementary chemical and molecular analysis of breast calcifications and soft tissue using spectroscopy and XRD imaging predicts the likely progression of DCIS to IBC. Subject to the ongoing validation of biomarkers, these approaches appear as promising DCIS risk assessment tools that can inform diagnosis, prognosis and treatment options. Citation Format: Jayakrupakar Nallala, Doriana Calabrese, Sarah Gosling, Esther Lips, Rachel Factor, Allison Hall, Sarah Pinder, Ihssane Bouybayoune, Elinor Sawyer, Lorraine King, Jeffrey Marks, Thomas Lynch, Donna Pinto, Jelle Wesseling, Shelley Hwang, Keith Rogers, Nick Stone, Grand Challenge PRECISION consortium. Molecular imaging of calcification and soft tissue defines prognosis of DCIS to invasive breast cancer. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 5561.

Study of the Molecular Structure of Proteins in Eggs under Different Storage Conditions

The aim of this study is to reveal the relationship between changes in the physical and chemical characterization of eggs during storage and to provide a new way to assess egg freshness at the molecular chemical level. In this study, the Fourier transform infrared (FTIR) spectra of egg albumin from 60 fresh eggs (ISA Brown layer) stored for 1, 10, 20, 30, and 40 days at 4°C and 10°C were measured ( n = 6 ), and the amide I band of the egg albumin spectra was quantified by Fourier deconvolution and curve fitting to obtain the composition of the protein molecular structure. The results showed that different storage temperatures and storage times led to protein denaturation, resulting in changes in the conformation of the protein secondary structure. With increasing storage temperature and storage time, the content of the ordered structures β-sheet and α-helix in the egg protein secondary structure decreased significantly ( p &lt; 0.05 ), and the content of the disordered structure β-turn and random coil increased significantly ( p &lt; 0.05 ). Based on the pattern of protein secondary structure changes during storage, it was found that fresh eggs were better stored at 4°C for up to 15 days. Spearman’s correlation analysis of egg protein height, Haugh unit, egg weight, and protein secondary structure in eggs stored at 4°C showed a significant positive correlation between β-sheet and α-helix and egg weight, protein height, and Haugh unit. And a significant negative correlation between random coil and egg weight, protein height, and Haugh unit. Therefore, a curve fitting method based on Fourier transform infrared spectroscopy of deconvoluted spectra is an effective method for evaluating egg quality and freshness.

Preparation of quinoa protein with ultrasound pretreatment and its effects on the physicochemical properties, structural and digestion characterizations

This study aimed to investigate the effects of ultrasound pretreatment on the yield and the physicochemical properties, structural and digestion characterizations of quinoa protein (QP). Results showed that under the conditions of ultrasonic power density of 0.64 W/mL, ultrasonication time of 33 min, and the liquid-solid ratio of 24 mL/g, the highest yield of QP at 68.403 % was obtained, which was significantly higher than that without ultrasound pretreatment at 51.26 ± 1.76 % (P < 0.05). Ultrasound pretreatment decreased the average particle size and ζ-potential but increased the hydrophobicity of QP (P < 0.05). However, no significant protein degradation and secondary structure changes of QP by ultrasound pretreatment were observed. In addition, ultrasound pretreatment slightly improved the in vitro digestibility of QP and reduced the dipeptidyl peptidase IV (DPP-IV) inhibitory activity of the hydrolysate of QP by in vitro digestion. Overall, this work demonstrates that ultrasound-assisted extraction is appropriate for improving the extraction efficiency of QP.

Abstract P4-02-22: Breast microcalcification chemistry predicts DCIS prognosis

Abstract Introduction: Microcalcifications are a common feature in mammographic detection of ductal carcinoma in situ (DCIS), and occur in &amp;gt;80% of cases. Known to be present as type I (calcium oxalate-CaO) and type II (carbonated calcium hydroxyapatite-CHAP) microcalcifications, their association with DCIS and their role in the progression of DCIS to invasive breast cancer (IBC) remains unexplored. In an effort to understand the factors involved in DCIS prognosis, it is hypothesized that changes in the chemical composition of calcifications, in tandem with molecular changes in the surrounding soft tissue, will define patients with DCIS who will progress to develop IBC from those who remain with a stable DCIS phenotype. To this end, a novel label-free approach of hyperspectral imaging using mid-infrared (mid-IR) and Raman spectroscopy was used to probe calcification chemistry and molecular composition of the surrounding ductal and stromal soft tissue. The main aim of the work is to identify biomarkers for DCIS prognosis, based on chemical and molecular compositional changes of calcifications and the surrounding soft tissue. It is anticipated that the spectral biomarkers will provide patients and clinicians an informed risk assessment whether to undertake treatment for DCIS or to be placed under active surveillance. Methods: Tissue samples from 422 patient have been obtained and include (i) ‘pure DCIS’ (DCIS without recurrence) (n=193), (ii) ‘DCIS with invasive recurrence’ (DCIS from patients who subsequently were known to develop invasive disease) (n=123), (iii) ‘DCIS plus contemporaneous invasive cancer’ (n=44) and ‘benign’ (n=62) samples. Serial tissue sections were measured using mid-IR and Raman hyperspectral imaging approaches targeting the same calcification and soft tissue regions from specific DCIS ducts. Hyperspectral imaging data was initially pre-processed to digitally remove paraffin and unintended spectral interferences. The pre-processed data was subjected to cluster analysis followed by unsupervised and supervised machine learning classification models to identify spectral features associated with DCIS and its progression to IBC. Results: Cluster analysis based segmentation of hyperspectral images revealed histopathological features including calcifications, epithelium, necrotic areas, connective tissue and stroma. Spectra were extracted from each of the histopathological features using image coordinates, and biomodelling analysis was performed. Initial analysis of 314 calcification images from 170 patients with (i) ‘pure DCIS’ (n=118) and (ii) ‘DCIS with invasive recurrence’ (n=52) showed an area under the receiver operating characteristic (AUROC) mean value of 85% in distinguishing pure DCIS from DCIS that later recurred as IBC. The calcification features appeared to indicate pathology specific changes in phosphate and carbonate content as well as changes in magnesium whitlockite content. Similar analysis of the surrounding soft tissue spectral features showed an AUROC mean value of 85% (necrotic regions surrounding calcifications) and 76% (epithelium) respectively. The epithelial features showed changes in protein secondary structure and content, which together with the calcification changes indicate structural remodelling in DCIS that progresses to IBC, from those that do not. Perspectives: In the ongoing analyses of imaging data from 422 patients, it is anticipated that molecular/structural features from calcification and soft tissue imaging data will provide important cues in understanding DCIS prognosis and could be a promising way forward in determining management of DCIS risk and treatment underpinned by the identification of specific discriminatory spectral markers. Acknowledgments: This work was supported by Cancer Research UK and by KWF Kankerbestrijding (ref. C38317/A24043). Citation Format: Jayakrupakar Nallala, Doriana Calabrese, Sarah Gosling, Esther Lips, Rachel Factor, Allison Hall, Sarah E. Pinder, Ihssane Bouybayoune, Lorraine King, Jeffrey Marks, Thomas Lynch, Donna Pinto, Jelle Wesseling, E Shelley Hwang, Keith Rogers, Nick Stone. Breast microcalcification chemistry predicts DCIS prognosis [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P4-02-22.