X‑α‑L‑Ara

X‑α‑L‑Ara (CAS 1887197‑40‑1) is a synthetic α‑L‑arabinosidase‑specific chromogenic substrate in which a 5‑bromo‑4‑chloro‑3‑indolyl aglycone is linked via an α‑glycosidic bond to α‑L‑arabinopyranose. When hydrolyzed by α‑L‑arabinosidases (e.g., α‑L‑arabinofuranosidases and related GH‑51/GH‑62‑type enzymes), the glycosidic bond is cleaved to release the indole derivative and α‑L‑arabinose; the indole then undergoes air oxidation to form a strongly colored magenta‑ or blue‑colored precipitate or dye at the site of enzyme activity. This reaction makes X‑α‑L‑Ara especially useful for histochemical staining of α‑L‑arabinosidase activity in cells, tissues, and microbial colonies, as well as for high‑throughput screening of enzyme‑expressing clones or recombinant α‑L‑arabinosidases. The compound is typically supplied as a high‑purity, lyophilized or crystalline solid, compatible with standard aqueous or buffer‑based incubation systems. X‑α‑L‑Ara is widely used in glycobiology, plant‑biology, and microbiology to visualize α‑L‑arabinosidase‑dependent cleavage of arabinoxylans, arabinans, and other arabinosylated glycoconjugates, including studies of fungal and bacterial α‑L‑arabinosidases involved in hemicellulose and plant‑cell‑wall deconstruction.

Appearance

• Off‑white to pale yellow crystalline or lyophilized powder.
• Forms a pale yellow to colorless solution in aqueous buffer; develops a magenta‑ or blue‑colored precipitate only after enzymatic hydrolysis and oxidation of the indole‑type chromophore.

Source / synthesis

• Synthetically prepared by glycosylation of 5‑bromo‑4‑chloro‑3‑indole with α‑L‑arabinopyranose or a protected α‑L‑arabinoside, followed by deprotection and crystallization from aqueous or mixed‑solvent systems.
• Commercially supplied by glycobiology‑and‑enzyme‑substrate manufacturers (e.g., Hepattack, Shenzhen‑based vendors such as GeneSeqTools, ChemicalBook‑linked suppliers) as a high‑purity, research‑grade α‑L‑arabinosidase substrate.

Molecular weight and structure

• Molecular formula: C13H13BrClNO5
• Molecular weight: 378.60 g/mol.
• Structure: 5‑bromo‑4‑chloro‑3‑indolyl‑α‑L‑arabinopyranoside, with an α‑glycosidic linkage between the indole‑type aglycone and the anomeric carbon of α‑L‑arabinopyranose.

Sugar specificity

• Specifically hydrolyzed by α‑L‑arabinosidases and α‑L‑arabinoside‑cleaving glycosidases, including α‑L‑arabinofuranosidases that remove arabinose side‑chains from arabinoxylans and other plant polysaccharides.
• Frequently used in chromogenic panels and histochemical assays to distinguish α‑L‑arabinosidase activity from other glycosidases in microbial, plant, and fungal systems.

Biological activity

• Serves as a chromogenic reporter whose rate of indole‑derivative release under defined pH and temperature conditions reflects α‑L‑arabinosidase activity.
• Enables localization and relative quantification of α‑L‑arabinosidase activity in tissue sections, cell cultures, and microbial colonies, supporting studies on hemicellulose‑degrading and plant‑cell‑wall‑remodeling enzymes.

Purity and microbial contamination

• Typically described as a “high‑purity raw material” suitable for scientific research, with purity often ≥95% by HPLC‑type methods as indicated by supplier data sheets.
• Described as a non‑sterile, research‑grade solid, intended for use under standard clean‑laboratory or sterile‑handling conditions depending on the assay (e.g., histochemistry vs. colony‑screening).

Identity and quality control

• Identity based on CAS 1887197‑40‑1, molecular formula C13H13BrClNO5C13H13BrClNO5, and molecular weight 378.60 g/mol, with the systematic name 5‑bromo‑4‑chloro‑3‑indolyl‑α‑L‑arabinopyranoside.
• Quality‑control includes checks for appearance, solubility, spectral properties, and performance in a defined α‑L‑arabinosidase assay (e.g., chromogenic colony‑screen or histochemical staining of arabinosidase‑expressing cultures).

Shelf life and storage

• Shelf life is typically 12–24 months when stored at −20 °C in a tightly sealed, light‑protected container, as the indole‑type chromophore is sensitive to light and oxidation.
• Aqueous working solutions are best prepared fresh or used immediately, as prolonged storage or air‑exposure can cause premature color development or background staining.

Application

• Histochemical and chromogenic staining of α‑L‑arabinosidase activity in tissue sections, cell cultures, and microbial colonies.
• Screening of α‑L‑arabinosidase‑expressing clones in recombinant enzyme‑expression or mutagenesis studies.
• Use in plant‑biology, hemicellulose‑and‑biofuel‑research, and glycobiology to visualize α‑L‑arabinosidase‑dependent processing of arabinoxylans, arabinans, and other arabinosylated glycoconjugates.

Key characteristics

• Chromogenic readout: release of an indole derivative that oxidizes to a magenta‑ or blue‑colored precipitate, enabling easy visual detection of α‑L‑arabinosidase activity.
• Defined α‑L‑arabinopyranoside linkage providing selectivity for α‑L‑arabinosidases over many other glycosidases.
• High‑purity, lyophilized solid with a known molecular formula and weight, suitable for histochemical, colony‑, and microplate‑based assays.

Citations

• Hepattack – X‑α‑L‑Ara product page (CAS 1887197‑40‑1, MF C₁₃H₁₃BrClNO₅, MW 378.60, high‑purity raw material): https://www.hepattack.com/en/product03_cid_212_pid_500.html
• GeneSeqTools News – X‑α‑L‑Ara “in‑situ chromogenic tool” overview (CAS 1887197‑40‑1, 5‑bromo‑4‑chloro‑3‑indolyl‑α‑L‑arabinopyranoside): http://www.geneseqtools.cn/en/news‑detail_cid_29_id_147.html
• ChemicalBook (Chinese supplier listing) – 5‑bromo‑4‑chloro‑3‑indolyl‑α‑L‑arabinopyranoside (X‑α‑L‑Ara, CAS 1887197‑40‑1): https://www.chemicalbook.com/SupplyInfo_2757935.htm
• Biosynth – 5‑Bromo‑4‑chloro‑3‑indoxyl‑α‑L‑arabinopyranoside (fluorogenic‑/chromogenic substrate description, closely related to X‑α‑L‑Ara): https://www.biosynth.com/p/B-7046/5‑bromo‑4‑chloro‑3‑indoxyl‑alpha‑l‑arabinopyr
• α‑L‑arabinofuranosidase‑expression paper (e.g., GH62 α‑L‑arabinofuranosidases from Talaromyces amestolkiae): https://pmc.ncbi.nlm.nih.gov/articles/PMC10418624/
• Substrate‑specificity study of α‑L‑arabinofuranosidases (Aspergillus niger enzymes, context for arabinosidase‑substrate design): https://pubmed.ncbi.nlm.nih.gov/9614699/
• α‑L‑arabinofuranosidase product‑page (Megazyme, biological context for α‑L‑arabinosidase assays): https://www.megazyme.com/alpha‑l‑arabinofuranosidase‑aspergillus‑nidulans
• Megazyme α‑L‑arabinofuranosidase overview (enzyme‑assay context and natural substrates): https://www.megazyme.com/alpha‑l‑arabinofuranosidase‑aspergillus‑niger
• General glycosidase‑substrate catalog (X‑α‑L‑Ara and related indolyl‑arabinoside reagents overview): https://www.chemicalbook.com/ (search for “1887197‑40‑1”).
• Xylosidase/arabinosidase‑related structural review or method‑paper (e.g., on α‑L‑arabinosidase‑substrate specificity and assay design): https://pmc.ncbi.nlm.nih.gov/ (search “α‑L‑arabinosidase substrate X‑α‑L‑Ara”).