1. Cytoskeleton Neuronal Signaling Autophagy
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  3. MLCK inhibitor peptide 18

MLCK inhibitor peptide 18 

Cat. No.: HY-P1029 Purity: 99.87%
COA 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.

Custom Peptide Synthesis

MLCK inhibitor peptide 18 Chemical Structure

MLCK inhibitor peptide 18 Chemical Structure

CAS No. : 224579-74-2

Size Price Stock Quantity
1 mg USD 66 In-stock
5 mg USD 231 In-stock
10 mg USD 422 In-stock
25 mg USD 950 In-stock
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This product is a controlled substance and not for sale in your territory.

Customer Review

Based on 2 publication(s) in Google Scholar

Top Publications Citing Use of Products
  • Biological Activity

  • Protocol

  • Purity & Documentation

  • References

  • Customer Review


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



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].

MedChemExpress (MCE) has not independently confirmed the accuracy of these methods. They are for reference only.

Molecular Weight







White to off-white



Sequence Shortening



Room temperature in continental US; may vary elsewhere.


Sealed storage, away from moisture

Powder -80°C 2 years
-20°C 1 year

*In solvent : -80°C, 6 months; -20°C, 1 month (sealed storage, away from moisture)

Solvent & Solubility
In Vitro: 

H2O : 100 mg/mL (75.49 mM; Need ultrasonic)

Stock Solutions
Concentration Solvent 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.
In Vivo:
  • 1.

    Add each solvent one by one:  PBS

    Solubility: 100 mg/mL (75.49 mM); Clear solution; Need ultrasonic

*All of the co-solvents are available by MedChemExpress (MCE).
Purity & Documentation
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.

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MLCK inhibitor peptide 18 Related Classifications

Help & FAQs
  • Do most proteins show cross-species activity?

    Species cross-reactivity must be investigated individually for each product. Many human cytokines will produce a nice response in mouse cell lines, and many mouse proteins will show activity on human cells. Other proteins may have a lower specific activity when used in the opposite species.

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