$151.00 - $151.00
Kemptide Negative Control is a phosphorylation-deficient analog of Kemptide designed for use as a paired control in protein kinase A (PKA) and phosphopeptide assays.
The sequence Leu-Arg-Arg-Ala-Ala-Leu-Gly (LRRAALG) replaces the Ser5 phosphorylation site of native Kemptide with alanine, removing the hydroxyl group required for phosphorylation at that position.
Product Information
| Property | Specification |
|---|---|
| Product Name | Kemptide Negative Control |
| Catalog No. | AS2698 |
| Sequence | Leu-Arg-Arg-Ala-Ala-Leu-Gly |
| One-Letter Sequence | LRRAALG |
| Peptide Length | 7 amino acids |
| Molecular Weight | Approximately 755.93 Da |
| Molecular Formula | C32H61N13O8 |
| Key Substitution | Ser5 → Ala |
| Research Role | Non-phosphorylatable Kemptide control |
Ser5-to-Ala Control Design
Native Kemptide has the sequence LRRASLG and is phosphorylated by PKA at Ser5. The negative control substitutes alanine at this position to produce LRRAALG.
Alanine preserves a small side-chain geometry while removing the serine hydroxyl group required for phosphate transfer. This makes the analog useful for distinguishing phosphorylation-dependent signals from effects caused by peptide binding, assay reagents or nonspecific detection.
We consider this paired design more informative than using an unrelated peptide as a negative control because most of the Kemptide sequence is retained.
Using Kemptide and Its Negative Control Together
The control can be run alongside Kemptide in enzyme assays, phosphopeptide detection workflows and method-development experiments.
A strong response with Kemptide and minimal response with LRRAALG provides evidence that the measured signal depends on the target phosphoacceptor residue rather than simply on the basic peptide sequence.
Experimental Considerations
The negative control does not compensate for every source of assay background. Appropriate no-enzyme, no-ATP or inhibitor controls may still be needed depending on the detection format.
We recommend matching the purity, concentration and preparation conditions of the positive and negative peptides when making quantitative comparisons.
Frequently Asked Questions
What is the difference between Kemptide and Kemptide Negative Control?
Kemptide contains Ser5 and has the sequence LRRASLG. The negative control replaces this serine with alanine to produce LRRAALG.
Why is alanine used instead of serine?
Alanine lacks the hydroxyl group required for serine phosphorylation while introducing a relatively small structural change to the peptide.
Can other phosphorylation-site controls be prepared?
Ser-to-Ala, Thr-to-Ala and additional sequence-control designs can be evaluated through Chemical Peptide Synthesis.