1. Cytoskeleton
    Neuronal Signaling
  2. Myosin

MLCK inhibitor peptide 18 (Synonyms: RKKYKYRRK)

Cat. No.: HY-P1029 Purity: 98.71%
Handling Instructions

MLCK inhibitor peptide 18 is a myosin light chain kinase (MLCK) inhibitor with an IC50 of 50 nM, and inhibits CaM kinase II only at 4000-fold higher concentrations.

For research use only. We do not sell to patients.
MLCK inhibitor peptide 18 Chemical Structure

MLCK inhibitor peptide 18 Chemical Structure

CAS No. : 224579-74-2

Size Price Stock Quantity
10 mM * 1 mL in DMSO USD 560 In-stock
1 mg USD 60 In-stock
5 mg USD 210 In-stock
10 mg USD 384 In-stock
25 mg USD 864 In-stock
50 mg   Get quote  
100 mg   Get quote  

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Customer Review

  • Biological Activity

  • Protocol

  • Technical Information

  • Purity & Documentation

  • References


MLCK inhibitor peptide 18 is a myosin light chain kinase (MLCK) inhibitor with an IC50 of 50 nM, and inhibits CaM kinase II only at 4000-fold higher concentrations.

IC50 & Target

IC50: 50 nM (MLCK)[1]

In Vitro

MLCK inhibitor peptide 18 has a selective effect on peptide substrate utilization by MLCK, does not interfere with kinase activation by CaM, does not have significant inhibitory activity with the closely related CaMPKII, and does not inhibit PKA[1].

Preparing Stock Solutions
Concentration Volume Mass 1 mg 5 mg 10 mg
1 mM 0.7549 mL 3.7747 mL 7.5493 mL
5 mM 0.1510 mL 0.7549 mL 1.5099 mL
10 mM 0.0755 mL 0.3775 mL 0.7549 mL
Please refer to the solubility information to select the appropriate solvent.
Kinase Assay

All assays are done in a final volume of 50 μL. Each point is tested in duplicate. The standard assay conditions are 50 mM HEPES, 0.2 mM [γ-32P]ATP (specific activity 200−300 cpm/pmol), 1 mM DTT, 1 mg/mL bovine serum albumin, 5 mM MgCl2, 150 mM KCl, 15 mM NaCl, pH 7.5, with or without inhibitors. Synthetic substrate concentrations, KKRPQRATSNVFAM-NH2 for MLCK, PLRRTLSVAA-NH2 for CaMPKII, and LRRASLG for PKA, are 20 μM. The reactions are initiated with the addition of 5 μL of enzyme (PKA) or enzyme:CaM complex (for MLCK and CaMPKII). Enzyme:CaM complexes are preformed by incubation of enzyme in ice for 1 min in the presence of 1 μM CaM and 5 μM CaCl2 (for MLCK) or 30 μM CaM and 2 mM CaCl2 (for CaMPKII). Assay conditions are 20 min, 25°C for MLCK; 8 min, 25°C for CaMPKII; 6 min, 25°C for PKA. Aliquots of each reaction tube are spotted into phosphocellulose filter paper. Filters are washed in 75 mM phosphoric acid solution, followed by 95% ethanol, dried, and placed into vials containing 10 mL of Ecoscint O. Radioactivity is determined by counting vials in a Beckman 6500 liquid scintillation counter. No quenching corrections are applied. Data are transformed as percent of the maximal enzyme activity, where enzyme activity in the absence of inhibitors is taken as 100%. ICsub>50 values are calculated by a linear regression data analysis on data points corresponding to 15%−85% of maximal activity. This analysis is done using InPlot version 4.0. MCE has not independently confirmed the accuracy of these methods. They are for reference only.

Molecular Weight







OC(C=C1)=CC=C1C[[email protected]@H](C(N[[email protected]@H](CCCNC(N)=N)C(N[[email protected]@H](CCCNC(N)=N)C(N[[email protected]](C(N)=O)CCCCN)=O)=O)=O)NC([[email protected]](CCCCN)NC([[email protected]@H](NC([[email protected]](CCCCN)NC([[email protected]](CCCCN)NC([[email protected]@H](N)CCCNC(N)=N)=O)=O)=O)CC2=CC=C(O)C=C2)=O)=O

Powder -80°C 2 years
  -20°C 1 year
In solvent -80°C 6 months
  -20°C 1 month

Room temperature in continental US; may vary elsewhere

Solvent & Solubility


* "<1 mg/mL" means slightly soluble or insoluble. "≥" means soluble, but saturation unknown.

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MLCK inhibitor peptide 18
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