An efficient approach for overproduction of DNA polymerase from Pyrococcus furiosus using an optimized autoinduction system in Escherichia coli.

High fidelity DNA polymerase from Pyrococcus furiosus (Pfupol) is an attractive alternative to the highly popular DNA polymerase from Thermus aquaticus. Because this enzyme is in great demand for biotechnological applications, optimizing Pfupol production is essential to supplying the industry's expanding demand. T7-induced promoter expression in Escherichia coli expression systems is used to express recombinant Pfupol; however, this method is not cost-effective. Here, we have effectively developed an optimized process for the autoinduction approach of Pfupol expression in a defined medium. To better examine Pfupol's activities, its purified fraction was used. A 71 mg/L of pure Pfupol was effectively produced, resulting in a 2.6-fold increase in protein yield when glucose, glycerol, and lactose were added in a defined medium at concentrations of 0.05%, 1%, and 0.6%, respectively, and the condition for production in a 5 L bioreactor was as follow: 200 rpm, 3 vvm, and 10% inoculant. Furthermore, the protein exhibited 1445 U/mg of specific activity when synthesized in its active state. This work presents a high level of Pfupol production, which makes it an economically viable and practically useful approach.

[Research progress in the synthesis of 3'- and 6'-sialactose by Escherichia coli].

Human milk oligosaccharides (HMOs) are a structurally complex group of unbound polysaccharides, representing the third-largest solid component in breast milk. They play a crucial role in the intestinal health and immune system development of infants. Sialylated HMOs, including 3'-sialactose (3'-SL) and 6'-sialactose (6'-SL), are major components of HMOs, playing significant roles in immune regulation, anti-inflammatory processes, and promotion of probiotic growth. Currently, the cost-effective production of high-value sialactose by microbial fermentation with readily available raw materials has become a research hotspot due to the high nutritional value and potential applications of sialylated HMOs in infant food. This paper summarizes the functions and biosynthesis of 3'-SL and 6'-SL. Furthermore, it reviews the research progress in the synthesis of sialactose by Escherichia coli, offering valuable insights for future industrial production.

Rational modification of Neisseria meningitidis ß1,3-N-acetylglucosaminyltransferase for lacto-N-neotetraose synthesis with reduced long-chain derivatives.

Lacto-N-neotetraose (LNnT), as a neutral core structure within human milk oligosaccharides (HMOs), has garnered widespread attention due to its exceptional physiological functions. In the process of LNnT synthesis using cellular factory approaches, substrate promiscuity of glycosyltransferases leads to the production of longer oligosaccharide derivatives. Here, rational modification of ß1,3-N-acetylglucosaminyltransferase from Neisseria meningitidis (LgtA) effectively decreased the concentration of long-chain LNnT derivatives. Specifically, the optimal ß1,4-galactosyltransferase (ß1,4-GalT) was selected from seven known candidates, enabling the efficient synthesis of LNnT in Escherichia coli BL21(DE3). Furthermore, the influence of lactose concentration on the distribution patterns of LNnT and its longer derivatives was investigated. The modification of LgtA was conducted with computational assistance, involving alanine scanning based on molecular docking to identify the substrate binding pocket and implementing large steric hindrance on crucial amino acids to obstruct LNnT entry. The implementation of saturation mutagenesis at positions 223 and 228 of LgtA yielded advantageous mutant variants that did not affect LNnT synthesis while significantly reducing the production of longer oligosaccharide derivatives. The most effective mutant, N223I, reduced the molar ratio of long derivatives by nearly 70 %, showcasing promising prospects for LNnT production with diminished byproducts.

Untargeted metabolomic analysis of human milk from healthy mothers reveals drivers of metabolite variability.

Understanding the human milk metabolome can help inform infant nutrition and health. Untargeted metabolomics was used to study breast milk from 31 healthy participants to assess the shared metabolites in milk from participants with various backgrounds and understand how different demographic, health, and environmental factors impact the milk metabolome. Breast milk samples were analyzed by four separate UPLC-MS/MS methods. Metabolite Set Enrichment Analysis was used to study the most and least variable metabolites. The associations between participant factors and the metabolome were assessed with redundancy analyses. Among all 31 participants and between each untargeted UPLC-MS/MS method, 731 metabolites were detected, of which 389 were shared among all participants. Of the shared metabolites, lactose was the least and lactobionate the most variable metabolite. In the biological super pathway analysis, xenobiotics were the most variable metabolites. Infant age, maternal age, number of live births, and pre-pregnancy BMI were associated with the milk metabolome. In conclusion, the most variable metabolites originate from environmental exposures while the well-conserved core metabolites are linked to cell metabolism or are crucial for infant nutrition and osmoregulation. Understanding the variability of the breast milk metabolome can help identify components that are crucial for infant nutrition, growth, and development.

Human milk oligosaccharides are associated with maternal genetics and respiratory health of human milk-fed children.

Breastfeeding provides many health benefits, but its impact on respiratory health remains unclear. This study addresses the complex and dynamic nature of the mother-milk-infant triad by investigating maternal genomic factors regulating human milk oligosaccharides (HMOs), and their associations with respiratory health among human milk-fed infants. Nineteen HMOs are quantified from 980 mothers of the CHILD Cohort Study. Genome-wide association studies identify HMO-associated loci on chromosome 19p13.3 and 19q13.33 (lowest P = 2.4e-118), spanning several fucosyltransferase (FUT) genes. We identify novel associations on chromosome 3q27.3 for 6'-sialyllactose (P = 2.2e-9) in the sialyltransferase (ST6GAL1) gene. These, plus additional associations on chromosomes 7q21.32, 7q31.32 and 13q33.3, are replicated in the independent INSPIRE Cohort. Moreover, gene-environment interaction analyses suggest that fucosylated HMOs may modulate overall risk of recurrent wheeze among preschoolers with variable genetic risk scores (P < 0.01). Thus, we report novel genetic factors associated with HMOs, some of which may protect the respiratory health of children.

Chemiosmotic nutrient transport in synthetic cells powered by electrogenic antiport coupled to decarboxylation.

Cellular homeostasis depends on the supply of metabolic energy in the form of ATP and electrochemical ion gradients. The construction of synthetic cells requires a constant supply of energy to drive membrane transport and metabolism. Here, we provide synthetic cells with long-lasting metabolic energy in the form of an electrochemical proton gradient. Leveraging the L-malate decarboxylation pathway we generate a stable proton gradient and electrical potential in lipid vesicles by electrogenic L-malate/L-lactate exchange coupled to L-malate decarboxylation. By co-reconstitution with the transporters GltP and LacY, the synthetic cells maintain accumulation of L-glutamate and lactose over periods of hours, mimicking nutrient feeding in living cells. We couple the accumulation of lactose to a metabolic network for the generation of intermediates of the glycolytic and pentose phosphate pathways. This study underscores the potential of harnessing a proton motive force via a simple metabolic network, paving the way for the development of more complex synthetic systems.

6'-Sialyllactose Alleviates Muscle Fatigue through Reduced Blood Lactate Level after Treadmill Exercise in Mice.

6'-Sialyllactose (6'-SL), found in human breast milk, exhibits anti-inflammatory, immune function-enhancing, brain development-promoting, and gut health-improving effects. However, its effects on muscle fatigue remain unknown. Here, we aimed to investigate the effects of 6'-SL on blood lactate level, muscle fiber type, and oxidative phosphorylation protein complexes (OXPHOS) in muscle after exercise using C57BL/6J male mice. C57BL/6J mice were randomly assigned to control or 100 mg/kg 6'-SL. After 12 weeks of 6'-SL administration, the mice were made to perform treadmill exercise; their blood lactate and glucose levels were measured at the basal level (rest) and 0, 5, and 10 min after treadmill exercise. Results showed that 6'-SL treatment in C57BL/6J mice significantly reduced blood lactate level and improved blood glucose level. Moreover, 6'-SL increased the expression of slow-myosin heavy chain (MHC) and OXPHOS in gastrocnemius muscle. In addition, 6'-SL treatment for 12 weeks did not affect food intake, serum biomarkers of tissue injury, and lipid profiles compared with those of the controls. These findings indicate that non-toxic 6'-SL suppressed muscle fatigue during exercise by promoting protein expression of muscle fibers, especially slow-twitch muscle fibers characterized by abundant OXPHOS complexes and decreased blood lactate level. This study suggests that 6'-SL holds promise as a nutritional supplement in exercise and clinical settings, subject to further validation.

Bovine Highly Pathogenic Avian Influenza Virus Stability and Inactivation in the Milk Byproduct Lactose.

The recent incursion of highly pathogenic influenza viruses into dairy cattle opens new insights for influenza virus ecology and its interspecies transmission and may have a significant impact on public health and agriculture. The aim of this study was to determine the stability of a bovine highly pathogenic avian influenza H5N1 virus isolate in the milk byproduct lactose and to evaluate two inactivation methods using industrial procedures. The bovine isolate of the highly pathogenic avian influenza H5N1 virus was stable for 14 days in a concentrated lactose solution under refrigerated conditions. Heat or citric acid treatments successfully inactivated the virus in lactose. This study highlights the persistence of HPAIV in lactose and its efficient inactivation under industrial standards.

Optimizing particle size segregation in vacuum drum-based capsule filling machines: A stirrer design approach.

This study investigates particle size segregation within the powder chamber of a vacuum drum-based capsule filling machine using various stirrer types and proposing novel designs to mitigate segregation. The stirrer is essential to the process, ensuring uniform density during volume-based filling. Three lactose grades, comprising 10% fine, 80% medium, and 10% coarse particles, were used, with tracer particles replacing fine or coarse particles, respectively. Dosages were collected over time for a line-array of five bores, and tracer concentrations were analysed using UV-Vis spectrophotometry. By visual assessments and stagnant zone observations particle segregation was evaluated and quantified by normalised tracer concentrations. Both standard and modified stirrers were examined under the same conditions. Stirrer type significantly influenced particle segregation, with the "spike" standard stirrer yielding the highest segregation, while the modified "3-wirem" and "coreless 3-wirem" stirrers exhibited superior performance, minimizing differences between fine and coarse particle concentrations and eliminating stagnant zones. These findings highlight promising prospects for further analysing the "3-wirem" and "coreless 3-wirem" stirrers. In that respect additional variables such as stirrer speed, rotation direction, and level of vacuum, need to be considered. Stirrer design significantly impacts vacuum drum-based capsule filling machine performance, ensuring reliable pharmaceutical capsule filling. This study offers insights into optimizing the industrial process.

Computer-aided mining of a psychrophilic cellobiose 2-epimerase from the Qinghai-Tibet Plateau gene catalogue.

Cellobiose 2-epimerase (CE) catalyzes the conversion of the lactose into its high-value derivatives, epilactose and lactulose, which has great prospects in food applications. In this study, CE sequences from the Qinghai-Tibet Plateau gene catalogue, we screened these for structural flexibility through molecular dynamics simulation to identify potential psychrophilic CE candidates. One such psychrophilic CE we termed psyCE demonstrated exceptional epimerization activity, achieving an optimum activity of 122.2 ± 1.6 U/mg. Its kinetic parameters (Kcat and Km) for epimerization activity were 219.9 ± 5.6 s-1 and 261.9 ± 18.1 mM, respectively, representing the highest Kcat recorded among known cold-active CEs. Notably, this is the first report of a psychrophilic CE. The psyCE can effectively produce epilactose at 8 °C, converting 20.3 % of 200 mM lactose into epilactose within four hours. These findings suggest that psyCE is highly suitable for cryogenic food processing, and glaciers may serve as a valuable repository of psychrophilic enzymes.

Enhancement of ß-galactosidase catalytic activity and stability through covalent immobilization onto alginate/tea waste beads and evaluating its impact on the quality of some dairy products.

The current study aimed to evaluate the hydrolysis of whole fat milk (WFM) and sweet whey (SW) using ß-galactosidase (ß-gal) after covalent immobilization onto activated alginate/tea waste (Alg/TW) beads as a novel carrier. The optimum temperature for free and Alg/TW/ß-gal was 40 °C and the ideal pH was 7.0. However, Alg/TW/ß-gal displayed better stabilities at high temperatures and a wide pH range. Additionally, the value of Km and Vmax for Alg/TW/ß-gal was higher than the free enzyme. The Alg/TW/ß-gal showed better residual activity (78.6 %) after 90 storage days at 4 °C. The reusability of Alg/TW/ß-gal was very good as it conserved its full activity after 15 consecutive cycles and conserved 93 % of its initial activity after 10 cycles with ONPG (O-nitrophenyl-ß-D-galactopyranoside) and lactose as a substrate, respectively. The impact of Alg/TW/ß-gal on WFM and SW using HPLC analysis revealed a remarkable decrease in lactose concentration and increase of glucose and galactose concentrations. The SW exhibited higher degree of lactose hydrolysis (97.3 %) compared to WFM (62.4 %). Besides, SW had a prominent increase in total phenolic content (96.8 mg/L) compared to WFM (54.3 mg/L). The antioxidant activity had increased after enzyme treatment in both WFM and SW. The GC-MS analysis for volatile compounds identified twenty-five flavour constituents. Finally, Alg/TW/ß-gal has a potential application for obtaining healthy, acceptable, and commercial dairy products of low lactose.

Coactivator-independent vitamin D receptor signaling causes severe rickets in mice, that is not prevented by a diet high in calcium, phosphate, and lactose.

The vitamin D receptor (VDR) plays a critical role in the regulation of mineral and bone homeostasis. Upon binding of 1α,25-dihydroxyvitamin D3 to the VDR, the activation function 2 (AF2) domain repositions and recruits coactivators for the assembly of the transcriptional machinery required for gene transcription. In contrast to coactivator-induced transcriptional activation, the functional effects of coactivator-independent VDR signaling remain unclear. In humans, mutations in the AF2 domain are associated with hereditary vitamin D-resistant rickets, a genetic disorder characterized by impaired bone mineralization and growth. In the present study, we used mice with a systemic or conditional deletion of the VDR-AF2 domain (VdrΔAF2) to study coactivator-independent VDR signaling. We confirm that ligand-induced transcriptional activation was disabled because the mutant VDRΔAF2 protein was unable to interact with coactivators. Systemic VdrΔAF2 mice developed short, undermineralized bones with dysmorphic growth plates, a bone phenotype that was more pronounced than that of systemic Vdr knockout (Vdr-/-) mice. Interestingly, a rescue diet that is high in calcium, phosphate, and lactose, normalized this phenotype in Vdr-/-, but not in VdrΔAF2 mice. However, osteoblast- and osteoclast-specific VdrΔAF2 mice did not recapitulate this bone phenotype indicating coactivator-independent VDR effects are more important in other organs. In addition, RNA-sequencing analysis of duodenum and kidney revealed a decreased expression of VDR target genes in systemic VdrΔAF2 mice, which was not observed in Vdr-/- mice. These genes could provide new insights in the compensatory (re)absorption of minerals that are crucial for bone homeostasis. In summary, coactivator-independent VDR effects contribute to mineral and bone homeostasis.

The efficacy of low/lactose-free milk powder in the treatment of lactose intolerance in infants: A protocol for systematic review and meta analysis.

BACKGROUND: The aim of this study was to evaluate the efficacy and safety of formula milk powder in the treatment of lactose intolerance in children, and to provide an evidence-based medicine basis for the rational use of drugs in children with lactose intolerance caused by various reasons by meta-analysis. METHODS: Use computers to search major databases, including Web of Science, PubMed, CNKI, Wanfang Data Knowledge Service Platform, and other databases, the retrieval time is from the establishment of the database to April 2023. The collected literatures were screened, data extracted and processed, and then meta-analysis was performed by Review-Manager 5.4 statistical software. RESULTS: A total of 10 randomized controlled trials were included, with 1112 patients, including 562 patients in the treatment group and 550 patients in the control group. The control group was treated with conventional therapy, and the treatment group was treated with lactose-free/low-lactose milk powder on the basis of conventional therapy. The results of the meta-analysis showed that the clinical efficacy of the treatment group was significantly better than that of the control group [odds ratio=6.01, 95% confidence interval (CI): 3.94-9.18, P<0.00001], the course of disease in the treatment group was shorter than that in the control group (mean difference=-1.45, 95% CI: -1.76 to -1.13, P<0.0001). The antidiarrhea time of the treatment group was shorter than that of the control group, and the difference between the 2 groups was statistically significant (mean difference=-1.41, 95% CI: -1.67 to -1.15, P<0.0001). CONCLUSION: Low/lactose-free milk powder can improve clinical efficacy and shorten the course of treatment in infants with lactose intolerance, which can be demonstrated by further large-scale clinical studies.

New theory to explain the effect of lactose fines on the performance of adhesive mixtures for inhalation.

A new theory for the dispersibility enhancing effect of excipient fines for adhesive mixtures for inhalation is presented in this paper, while at the same time the shortcomings of current hypotheses are discussed. The proposed mechanism, denoted the 'viscoelastic damping effect', states that the presence of fines particles acts to dampen the collisions between carrier particles during mixing. As a consequence, fewer fine particles are 'irreversibly' pressed into the carriers, which in turn entails a higher fine particle fraction. The mechanism was demonstrated experimentally at different levels of added lactose fines by studying the influence of processing on fine particle fraction. This approach furthermore enabled quantification of the effect. All fine particles present in the blend (APIs and excipient fines) act together to exert the damping effect. The proposed mechanism is able to explain the main body of published data, including the effect of added excipient fines, the effect of an increased drug load, and the effect of removal of carrier fines. The viscoelastic damping mechanism is general in nature and conveys a broader and more general understanding of the behavior of adhesive mixtures for inhalation.

6'-Sialyllactose Enhances Exercise Performance via Increased Muscle Mass and Strength.

Sialyllactose (SL) is a functional human milk oligosaccharide essential for immune support, brain development, intestinal maturation, and antiviral defense. However, despite its established health benefits, the effect of SL on exercise performance and muscle mass in mice remains unknown. Here, we aimed to investigate, for the first time, the effects of 6'-SL on muscle functions. Seven-week-old male C57BL/6J mice were administered 100 mg/kg 6'-SL for 12 weeks, after which exhaustive treadmill performance was conducted. Moreover, muscle strength was examined by grip strength, and muscle phenotype characteristics such as muscle mass, muscle fiber size, and muscle protein expression were also examined. The administration of 6'-SL significantly improved exhaustive treadmill performance metrics, including distance and exhaustion time. Grip strength was also increased by 6'-SL administration. Additionally, 6'-SL increased muscle mass in both the gastrocnemius (GAS) and soleus. 6'-SL administration led to an increase in the minimum Feret's diameter and the protein expression of total myosin heavy chain in the GAS muscle. In conclusion, 6'-SL administration in vivo led to increased running distance and time by increasing muscle mass and strength. These findings collectively indicate that 6'-SL is a potential agent for improving muscle health and exercise performance.

Optimizing dsRNA engineering strategies and production in E. coli HT115 (DE3).

Producing double-stranded RNA (dsRNA) represents a bottleneck for the adoption of RNA interference technology in agriculture, and the main hurdles are related to increases in dsRNA yield, production efficiency, and purity. Therefore, this study aimed to optimize dsRNA production in E. coli HT115 (DE3) using an in vivo system. To this end, we designed a new vector, pCloneVR_2, which resulted in the efficient production of dsRNA in E. coli HT115 (DE3). We performed optimizations in the culture medium and expression inducer in the fermentation of E. coli HT115 (DE3) for the production of dsRNA. Notably, the variable that had the greatest effect on dsRNA yield was cultivation in TB medium, which resulted in a 118% increase in yield. Furthermore, lactose induction (6 g/L) yielded 10 times more than IPTG. Additionally, our optimized up-scaled protocol of the TRIzol™ extraction method was efficient for obtaining high-quality and pure dsRNA. Finally, our optimized protocol achieved an average yield of 53.3 µg/mL after the production and purification of different dsRNAs, reducing production costs by 72%.

Biopharmaceutical studies of a novel sedative sublingual lozenge based on glycine and tryptophan: A rationale for mucoadhesive agent selection.

Effective sedative drugs are in great demand due to increasing incidence of nervous disorders. The present work was aimed to develop a novel sublingual sedative drug based on glycine and L-tryptophan amino acids. Carbopol and different hydroxypropyl methylcellulose species were alternatively tested as mucoadhesive agents intended to prolong tryptophan sublingual release time. A model lipid medium of fully hydrated L-α-dimyristoylphosphatidylcholine was used for optimal mucoadhesive agents selection. Simultaneous processes of drug release and diffusion in lipid medium were first investigated involving both experimental and theoretical approaches. Individual substances, their selected combinations as well as different drug formulations were consecutively examined. Application of kinetic differential scanning calorimetry method allowed us to reveal a number of specific drug-excipient effects. Lactose was found to essentially facilitate tryptophan release and provide its ability to get into the bloodstream simultaneously with glycine, which is necessary to achieve glycine-tryptophan synergism. Introduction of a mucoadhesive agent into the formulation was shown to change kinetics of drug-membrane interactions variously depending on viscosity grade. Among the mucoadhesive agents, hydroxypropyl methylcellulose species K4M and E4M were shown to further accelerate drug release, therefore they were selected as optimal. Thus, effectiveness of the novel sedative drug was provided by including some excipients, such as lactose and the selected mucoadhesive agent species. A dynamic mathematical model was developed properly describing release and diffusion in lipid medium of various drug substances. Our study clearly showed applicability of a lipid medium to meet challenges such as drug-excipient interactions and optimization of drug formulations.

An interaction-based mixing model for predicting porosity and tensile strength of directly compressed ternary blends of pharmaceutical powders.

Predicting the mechanical properties of powder mixtures without extensive experimentation is important for model driven design in solid dosage form manufacture. Here, a new binary interaction-based model is proposed for predicting the compressibility and compactability of directly compressed pharmaceutical powder mixtures based on the mixture composition. The model is validated using blends of MCC, lactose and paracetamol or ibuprofen. Both compressibility and compactability profiles are predicted well for a variety of blend compositions of ternary mixtures for the two formulations. The model performs well over a wide range of compositions for both blends and better than either an ideal mixing model or a ternary interaction model. A design of experiments which reduces the amount of API required for fitting the model parameters for a new formulation is proposed to reduce amount of API required. The design requires only three blends containing API. The model gives similar performance to the well-known Reynolds et al. model (2017) when trained using the same data sets. The binary interaction model approach is generalizable to other powder mixture properties. The model presented in this work is limited to curve-fitting of empirical compaction models for mixtures of common pharmaceutical powders and is not intended to provide guidance on the practical operating space (or design space) limits.

Synergistic effect of magnesium stearate and fine lactose in improving aerosolization performance of fluticasone propionate in dry powder formulation.

Magnesium stearate (MgSt) and lactose fines are often used as ternary components in carrier-based dry powder inhalers (DPIs) to improve fine particle fraction (FPF), but whether they act synergistically to improve aerosolization performance of DPI formulations is currently less studied. In addition, the applicability of utilizing powder rheological parameters to predict the FPF needs to be further verified. Thus, in this study, using fluticasone propionate (FP) as a model drug, effect of lactose fines addition in 0.5% MgSt containing DPI formulations on their powder and aerodynamic properties was explored. Influence of MgSt and fines mixing order on the DPIs performance was also investigated. The results showed that addition of lactose fines (1-10%) in 0.5% MgSt containing formulations could further improve flowability and enhance adhesion of the mixtures, and they could act synergistically to improve FPF. Moreover, the presence of 0.5% MgSt can greatly reduce the amount of lactose fines required to achieve the comparable FPF. The mixing order can affect distribution of MgSt on the carrier surface, with higher FPF noted when MgSt was mixed with carrier first, followed by lactose fines. A good linear relationship between powder rheological parameters such as basic flowability energy (BFE), Permeability and FPF was disclosed. In conclusion, in FP based DPIs, MgSt and lactose fines act synergistically to enhance FPF by tuning powder characteristics. Good flowability (27.39%) and strong adhesion (72.61%) contributed to the enhanced drug deposition in the lung.

LacdiNAc to LacNAc: remodelling of bovine α-lactalbumin N-glycosylation during the transition from colostrum to mature milk.

α -Lactalbumin, an abundant protein present in the milk of most mammals, is associated with biological, nutritional and technological functionality. Its sequence presents N-glycosylation motifs, the occupancy of which is species-specific, ranging from no to full occupancy. Here, we investigated the N-glycosylation of bovine α-lactalbumin in colostrum and milk sampled from four individual cows, each at 9 time points starting from the day of calving up to 28.0 d post-partum. Using a glycopeptide-centric mass spectrometry-based glycoproteomics approach, we identified N-glycosylation at both Asn residues found in the canonical Asn-Xxx-Ser/Thr motif, i.e. Asn45 and Asn74 of the secreted protein. We found similar glycan profiles in all four cows, with partial site occupancies, averaging at 35% and 4% for Asn45 and Asn74, respectively. No substantial changes in occupancy occurred over lactation at either site. Fucosylation, sialylation, primarily with N-acetylneuraminic acid (Neu5Ac), and a high ratio of N,N'-diacetyllactosamine (LacdiNAc)/N-acetyllactosamine (LacNAc) motifs were characteristic features of the identified N-glycans. While no substantial changes occurred in site occupancy at either site during lactation, the glycoproteoform (i.e. glycosylated form of the protein) profile revealed dynamic changes; the maturation of the α-lactalbumin glycoproteoform repertoire from colostrum to mature milk was marked by substantial increases in neutral glycans and the number of LacNAc motifs per glycan, at the expense of LacdiNAc motifs. While the implications of α-lactalbumin N-glycosylation on functionality are still unclear, we speculate that N-glycosylation at Asn74 results in a structurally and functionally different protein, due to competition with the formation of its two intra-molecular disulphide bridges.