p‑Nitrophenyl‑β‑L‑arabinopyranoside (PNP‑β‑L‑Arabinopyranoside)

p‑Nitrophenyl‑β‑L‑arabinopyranoside (PNP‑β‑L‑Arabinopyranoside, CAS 72732‑54‑8) is a synthetic β‑glycoside substrate in which a 4‑nitrophenyl aglycone is linked via a β‑glycosidic bond to the anomeric carbon of L‑arabinose in the pyranose form. When hydrolyzed by β‑l‑arabinopyranosidases or related β‑glycosidases, the glycosidic bond is cleaved to release 4‑nitrophenol and L‑arabinose. In mildly alkaline buffer (pH 8–8.5), 4‑nitrophenol ionizes to form a yellow‑colored phenolate anion whose absorbance at 400–410 nm can be measured continuously, providing a convenient readout of enzyme velocity. PNP‑β‑L‑Arabinopyranoside is used to characterize β‑l‑arabinopyranosidase activity from microbial and plant sources, to study enzyme‑substrate specificity among PNP‑glycosides, and to quantify activity in enzyme‑kinetic experiments (Km, Vmax). The compound is water‑soluble, supplied as a high‑purity, crystalline powder, and is suitable for biochemical and glycosidase‑related research.

Appearance

• Colorless to pale yellow crystalline powder.
• Forms a clear, colorless solution in water or buffer; develops a yellow color only after enzymatic hydrolysis and alkaline adjustment.

Source / synthesis

• Synthetically produced by glycosylation of 4‑nitrophenol with β‑L‑arabinopyranose or a protected β‑L‑arabinoside derivative, followed by deprotection and crystallization from water or aqueous alcohols.
• Commercially manufactured and supplied by biochemical‑reagent vendors (e.g., Shenzhen GeneSeqTools, Chem‑Synlab, ChemicalBook‑linked suppliers) as a high‑purity research‑grade substrate for β‑l‑arabinopyranosidases.

Molecular weight and structure

• Molecular formula: C11H13NO7C11​H13​NO7​.
• Molecular weight: 271.22 g/mol.
• Structure: 4‑nitrophenyl β‑L‑arabinopyranoside, with a β‑glycosidic linkage between the aromatic 4‑nitrophenyl group and the anomeric oxygen of the L‑arabinose ring in the pyranose form.

Sugar specificity

• Specifically hydrolyzed by β‑l‑arabinopyranosidases and related β‑glycosidases acting on β‑L‑arabinosyl linkages.
• Frequently used to distinguish β‑l‑arabinopyranosidase activity from other β‑glycosidases and α‑glycosidase activities in enzyme‑profiling panels.

Biological activity

• Serves as a chromogenic reporter whose rate of 4‑nitrophenol release under defined pH and temperature reflects β‑l‑arabinopyranosidase activity.
• Enables determination of kinetic parameters (Km, Vmax), inhibitor‑IC₅₀, and comparative activity profiling of different glycosidases, particularly in microbial and plant studies.

Purity and microbial contamination

• Typically supplied as a high‑purity raw material (e.g., ≥97–99% purity indicated in supplier documentation) for scientific research.
• Described as non‑sterile, research‑grade powder suitable for use in standard enzymatic assays when handled under clean‑laboratory conditions.

Identity and quality control

• Identity inferred from molecular formula, molecular weight, UV‑Vis spectral profile (4‑nitrophenol‑like absorbance), and NMR‑type data consistent with 4‑nitrophenyl‑β‑L‑arabinopyranoside.
• Quality‑control usually includes checks for appearance, solubility, elemental composition, and performance in a defined β‑l‑arabinopyranosidase activity assay (e.g., Streptomyces or Arabidopsis‑type enzymes using PNP‑β‑l‑Ara).

Shelf life and storage

• Shelf life is generally 12–24 months when stored as a dry powder at –20 °C in a tightly sealed, light‑protected container, shielded from moisture.
• Aqueous working solutions are best prepared fresh or stored at 4 °C for short periods, as alkaline pH and increased temperature can promote nonspecific hydrolysis and background absorbance.

Application

• Enzyme‑kinetic assays and specificity studies of β‑l‑arabinopyranosidases from bacteria (e.g., Streptomyces) and plants (e.g., Arabidopsis).
• Use in glycosidase‑profiling panels to map substrate‑specificity patterns among different PNP‑glycosides.
• Inhibitor‑screening and enzyme‑mechanism‑elucidation studies involving arabinoxylan and cell‑wall‑related glycosidases.

Key characteristics

• Colorimetric readout based on 4‑nitrophenol release, enabling spectrophotometric quantification of β‑l‑arabinopyranosidase activity.
• Defined β‑L‑arabinopyranoside linkage providing selectivity for β‑l‑arabinopyranosidases over many α‑glycosidases.
• Crystalline, stable powder with a known molecular formula and weight, suitable for quantitative enzyme assays and standardized protocols.

Citations

• ChemicalBook – P‑Nitrophenyl‑β‑L‑arabinopyranoside (CAS 72732‑54‑8, C₁₁H₁₃NO₇, MW 271.22): https://amp.chemicalbook.com/ChemicalProductProperty_EN_CB6135883.htm
• Chem‑Synlab – 4‑Nitrophenyl‑β‑L‑arabinopyranoside (CAS 72732‑54‑8) product page: http://www.chemsynlab.com/en/product/72732-54-8.html
• Shenzhen GeneSeqTools – PNP‑β‑L‑Arabinopyranoside product listing (CAS 72732‑54‑8, high‑purity raw material for scientific research): http://geneseqtools.cn/en/product03_cid_217_pid_570.html
• PMC article on a β‑l‑arabinopyranosidase from Streptomyces avermitilis using PNP‑β‑l‑Ara as primary substrate (activity assay method and units definition): https://pmc.ncbi.nlm.nih.gov/articles/PMC2757213/
• Journal of Experimental Botany – Arabidopsis β‑l‑arabinopyranosidases characterized using PNP‑β‑l‑Arap as substrate: https://academic.oup.com/jxb/article/68/16/4651/4079678
• PubChem – 4‑Nitrophenyl‑α‑L‑arabinopyranoside entry (for structural and glycoside‑substrate context, CAS 1223‑07‑0): https://pubchem.ncbi.nlm.nih.gov/compound/644162
• Sigma‑Aldrich – 4‑Nitrophenyl‑α‑L‑arabinopyranoside product page (for general PNP‑arabinoside assay context): https://www.sigmaaldrich.com/US/en/product/sigma/n3512
• BRENDA enzyme database reference using PNP‑glycosides (including PNP‑arabinosides) for glycosidase‑activity profiling: https://brenda-enzymes.info/literature.php?r=700334
• Applied and Environmental Microbiology – work on arabinoxylan‑degrading enzymes (context for β‑arabinosidase‑substrate use): https://journals.asm.org/doi/10.1128/aem.00685-14
• General glycosidase‑substrate catalog (PNP‑β‑L‑Arabinopyranoside and related PNP‑glycosides overview): https://www.chemicalbook.com/ (search for “72732‑54‑8”)