Kemptide [LRRASLG]

Product Name: Kemptide [LRRASLG]

Sequence One Letter Code: LRRASLG

Sequence Three Letter Code: H-Leu-Arg-Arg-Ala-Ser-Leu-Gly-OH

Cas No: 65189-71-1

Chemical Formula:C32H61N13O9

Molecular Weight: 772

Purity: 95%

Form: Lyophilized

Storage Conditions: - 20 °C

Research Area: Peptide Series

SMILES: C[C@@H](C(=O)N[C@@H](CO)C(=O)N[C@@H](CC(C)C)C(=O)NCC(=O)O)NC(=O)[C@H](CCCN=C(N)N)NC(=O)[C@H](CCCN=C(N)N)NC(=O)[C@H](CC(C)C)N

IUPAC: 2-[[(2S)-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-amino-4-methylpentanoyl]amino]-5-(diaminomethylideneamino)pentanoyl]amino]-5-(diaminomethylideneamino)pentanoyl]amino]propanoyl]amino]-3-hydroxypropanoyl]amino]-4-methylpentanoyl]amino]acetic acid

INCHIKEY: WIGDGIGALMYEBW-LLINQDLYSA-N

INCHI:

InChI=1S/C32H61N13O9/c1-16(2)12-19(33)26(50)42-21(9-7-11-39-32(36)37)29(53)43-20(8-6-10-38-31(34)35)28(52)41-18(5)25(49)45-23(15-46)30(54)44-22(13-17(3)4)27(51)40-14-24(47)48/h16-23,46H,6-15,33H2,1-5H3,(H,40,51)(H,41,52)(H,42,50)(H,43,53)(H,44,54)(H,45,49)(H,47,48)(H4,34,35,38)(H4,36,37,39)/t18-,19-,20-,21-,22-,23-/m0/s1

Source / Species: porcine

Conjugation: Unconjugated

Code Nacres: NA.26

Application: Kemptide is a synthetic heptapeptide widely used as a standard substrate for protein kinase A (PKA). It contains a consensus phosphorylation motif that is efficiently recognized by PKA, with a Km of approximately 16 µM. Due to its high specificity and simplicity, Kemptide is extensively used in kinase activity assays, enzyme kinetics studies, and signal transduction research involving cAMP-dependent pathways. It provides a reliable model substrate for evaluating kinase function and inhibitor activity. Modified versions, including fluorescently labeled and biotinylated derivatives, further expand its applications in detection and high-throughput assays. Kemptide remains a benchmark tool for studying phosphorylation mechanisms and PKA-mediated cellular signaling.

Current Research: Kemptide is a synthetic heptapeptide (typically with the sequence Leu-Arg-Arg-Ala-Ser-Leu-Gly) that serves as a canonical substrate for protein kinase A (PKA). Designed to incorporate the optimal consensus phosphorylation motif recognized by PKA, Kemptide has become one of the most widely used tools in studies of protein phosphorylation, kinase activity, and cAMP-dependent signaling pathways. Its well-defined structure, high specificity, and reproducible kinetics make it a standard reference substrate in biochemical and cellular assays. PKA and cAMP-Dependent Signaling Protein kinase A (PKA) is a central mediator of cAMP-dependent signal transduction, regulating a wide range of cellular processes including metabolism, gene expression, and cell proliferation. Upon activation by cyclic AMP, PKA phosphorylates target proteins at specific serine or threonine residues within defined consensus sequences. Kemptide was specifically designed to mimic this consensus motif, enabling efficient phosphorylation by PKA in vitro. As a result, it provides a simplified and controlled system for studying PKA enzymatic activity and substrate recognition. Structural Features and Phosphorylation Motif The sequence of Kemptide contains a basic residue-rich motif (Arg-Arg-X-Ser) that is critical for recognition by PKA. The serine residue serves as the phosphorylation site, while the surrounding amino acids enhance binding affinity and catalytic efficiency. Key characteristics include: High specificity for PKA, minimizing off-target phosphorylation Efficient catalytic turnover, enabling sensitive activity measurements Defined phosphorylation site, simplifying analysis of reaction products The reported Km value of approximately 16 µM reflects its strong affinity for PKA, making it suitable for quantitative enzyme kinetics studies. Applications in Kinase Assays and Enzyme Kinetics Kemptide is extensively used as a model substrate in PKA activity assays. Its simplicity allows researchers to measure kinase activity with high precision and reproducibility. Common applications include: Enzyme kinetics studies, including Km and Vmax determination Quantification of PKA activity in biochemical assays Screening of kinase inhibitors targeting PKA Comparative studies of kinase specificity and efficiency Because the peptide is small and well-characterized, it enables straightforward detection of phosphorylation using radiolabeling, fluorescence, or other analytical methods. Role in Signal Transduction Research Beyond in vitro assays, Kemptide is widely used to investigate cAMP-mediated signaling pathways. By serving as a surrogate substrate, it allows researchers to monitor PKA activation under different experimental conditions. This is particularly useful for studying: Intracellular signaling cascades regulated by cAMP Hormone and receptor-mediated activation of PKA Cross-talk between signaling pathways involving phosphorylation events Kemptide-based assays provide a reliable readout of PKA activity in both purified systems and cellular extracts. Modified Kemptide Derivatives To expand its utility, Kemptide has been adapted into various modified forms, including: Fluorescently labeled derivatives for real-time detection Biotinylated versions for affinity capture and assay integration Tagged variants for high-throughput screening platforms These modifications enable the peptide to be used in advanced applications such as: Fluorescence-based kinase assays High-throughput drug screening Protein–peptide interaction studies Such derivatives enhance sensitivity and allow integration into automated and multiplexed experimental systems. A Standard Tool for Phosphorylation Studies Kemptide remains a gold-standard substrate in kinase research due to its reliability, specificity, and ease of use. Its ability to provide consistent and quantifiable results makes it indispensable for studying PKA function, phosphorylation mechanisms, and enzyme inhibition. By offering a simplified model of kinase–substrate interaction, Kemptide continues to support advances in understanding signal transduction, enzymology, and therapeutic targeting of kinase pathways.