Nitrocefin is a cephalosporin with chromogenic properties and is routinely used to detect beta-lactamase enzymes produced by beta-lactam resistant bacteria. Nitrocefin is soluble in DMSO and is commonly used at a 1.0 mg/mL concentration.
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Essentially all beta-lactamase enzymes hydrolyze the amide bond between the carbonyl carbon and the nitrogen in the beta-lactam ring of nitrocefin. Macroscopic detection of this process is made possible because a ultraviolet absorption shift from intact versus hydrolyzed nitrocefin occurs within the visible light spectrum (~380 nm to ~500 nm, or yellow to red).
For in vitro research use only. Not suitable for human or animal consumption.
|Appearance||Orange powder/lyophilized film (depends on quantity).|
|Purity Level||(HPLC): ≥95.0%|
|Solubility||DMSO: Freely Soluble|
Methanol: Slightly Soluble
Water: 55.1 μg/mL
|Absorbance||Water: (0.5 mg/mL) 570nm ≤ 0.2
(0.5 mg/mL) 386nm ≥ 4.5 in Water|
|Melting Point||103-113 °C (dec); 167-169 °C (dec) (Lee)|
|Optical Rotation||[a]D20 -224° (c = 1.0 in dioxane)|
|Storage Conditions||Protect from light. Store with inert gas. 2-8°C|
Example of nitrocefin color change before and after exposure to beta-lactamase.
(A) Concentrated nitrocefin (10.0 mg/mL) in DMSO before dilution with PBS buffer. (B) Nitrocefin diluted with PBS buffer to working concentration (1.0 mg/mL). The yellow color is indicative of intact, undegraded nitrocefin. (C) 25 units of beta-lactamase dropped on top of nitrocefin (1.0 mg/mL in PBS). The red color is the result of beta-lactamase mediated cleavage of the nitrocefin. (D) Vortexed mixutre of contents shown in picture (C).
O'Callaghan, Cynthia H. et. al. "Novel Method for Detection of B-Lactamases by Using a Chromogenic Cephalosporin Substrate." Antimicrobial Agents and
Chemotherapy 1.4 (1972): 283-88. Ncbi.gov Web. 10 Oct. 2012.
Parr, T. R., Jr. "Simple Screening Method for Beta-lactamase-positive and -negative Ampicillin-resistant Haemophilus Influenzae Isolates." Journal of Clinical
Microbiology 20.1 (1984): 131-32. Ncbi.gov. Web. 10 Oct. 2012.