Biological Activity of Allolactose

Allolactose is a reducing disaccharide formed by combining D-galactose and D-glucose through β1-6 glycosidic bonds, which is an isomer of lactose. Lactose is converted into allolactose under the action of β-galactosidase, and allolactose is the inducer of the lactose operon, which plays a vital role in the metabolic process of cells. It binds to the repressor protein produced by the regulatory gene, making it lose its repression effect, so RNA polymerase binds to the promoter gene, activates the structural gene, and completes the transcription and translation process.

Allolactose isn’t decomposed and absorbed by enzymes in humans, so it enters the colon through the digestive tract, is fermented by intestinal bacteria, and produces beneficial short-chain fatty acids to provide energy for cells. Moreover, it helps to regulate the balance of intestinal flora and reduce the production of harmful substances for example ammonia and sulfide.

Fig.1 The structure of allolactose. (Wikipedia)

Allolactose Analysis Service at CD BioGlyco

• High-performance anion-exchange chromatography-pulse current detection (HPAEC-PAD)
  Sugar compounds exist in the form of anions in strong alkaline solutions due to weakly acidic and hydrophilic, which are charged and separated by a strong alkaline mobile phase, while the reductive nature of carbohydrates provides the possibility for direct amperometric detection. The method has been mostly applied in the determination of allolactose in recent years.
• Liquid chromatography-tandem mass spectrometry (LC-MS/MS)
  Combining the high-efficiency separation capability of HPLC with the specific detection capability of MS, the content of allolactose in the sample is analyzed more quickly, which has good specificity, high detection sensitivity, and is not interfered with by the matrix in the sample.
• Enzyme method
  Allolactose is hydrolyzed to galactose and glucose using the specific enzyme (β-galactosidase). Allolactose levels are determined indirectly using colorimetry or other quantitative methods to measure the amount of galactose or glucose produced.
• Biosensor method
  Allolactose in samples is typically measured using an electrode with a proprietary enzyme.

Fig.2. Allolactose analysis service. (CD BioGlyco)

Published Data

Paper Title: Determination of lactose in low-lactose and lactose-free dairy products using LC-MS

Technology: LC-MS

Journal: Journal of Food Composition and Analysis

IF: 4.52

Published: 2021

Results: The authors developed an LC-MS method to separate lactose, allolactose, and other sugars using an amide column under isocratic elution conditions. ¹³C labeled lactose was used as an internal standard, and the lactose chloride-35 adduct ion [M + ³⁵Cl] ^- (m/z 377) for quantification, and the detection was performed by single quadrupole MS in the negative ion mode of the electrospray ion source (ESI^-). The results showed that both allolactose and related sugars could be baseline-separated on LC-MS, which has high sensitivity and strong selectivity and is suitable for the determination of low-concentration sugars in various samples.

Fig.3 MS SIR chromatograms of allolactose and relevant sugars. (Yang, et al., 2021)

Applications

• Nutritional supplement: Since allolactose is not digested and absorbed by humans, it is used to develop dietary fiber supplements.
• Hydrolysis reagent: Allolactose is also treated as a hydrolysis reagent in the laboratory. Due to its special structure with glucose and galactose, which is applied to detect and analyze enzyme activity, carbohydrate metabolism pathways, and substrate specificity of related enzymes.

Advantages

• CD BioGlyco has developed standardized experimental procedures to ensure the consistency and reproducibility of allolactose analysis.
• Our scientists are familiar with various sample pretreatment methods and perform appropriate treatments for different samples to ensure accurate allolactose analysis results.
• CD BioGlyco provides customized allolactose analysis solutions and services according to the special needs of customers.

CD BioGlyco provides specialized high-level allolactose analysis services. Please feel free to contact us in time if you are curious about our analysis services and want to know more, and we will be happy to serve you.

References:

1. Lin, Y.K.; et al. Determination of galacto-oligosaccharide content in infant formula by semi-preparative high-performance liquid chromatography-ion chromatography. Food Safety Quality Inspection Journal. 2021, 12(13): 5145-5152.
2. Yang, J.; et al. Determination of lactose in low-lactose and lactose-free dairy products using LC-MS. Journal of Food Composition and Analysis. 2021, 100: 103824.