Proteinase K (PRK)

Proteinase K is a broad-specificity serine protease that digests proteins under both native and denaturing conditions, including in the presence of SDS and urea. It is widely used to degrade proteins and inactivate nucleases during DNA and RNA extraction and molecular diagnostic sample preparation.

Proteinase K Specifications at a Glance

Parameter	Lyophilized powder	Liquid
CAS number	39450-01-6	39450-01-6
EC number	3.4.21.64	3.4.21.64
Catalog numbers	HH4500-01 (100 mg), HH4500-02 (1 g), HH4500-03 (10 g), HH4500-04 (100 g), HH4500-99 (customized size)	HH4502-01, HH4502-02, HH4502-03, HH4502-04, HH4502-99 (customized size)
Appearance	White to off-white amorphous powder, lyophilized	Colorless to light-brown clear liquid
Activity	≥30 U/mg	≥800 U/ml (protein concentration ≥20 mg/ml)
DNase / RNase / nickase	None detected	None detected
Molecular weight	29 kDa (SDS-PAGE)	29 kDa (SDS-PAGE)
Optimum pH / temperature	pH 7.0–12.0 / 65°C	pH 7.0–12.0 / 65°C
Activators	SDS, urea	SDS, urea
Storage	Dry powder at ≤8°C, valid for 36 months; over 90% activity after 12 months at 25°C	2–8°C (valid for 36 months); ≤25°C (valid for 18 months)

Product Overview

Proteinase K is a stable serine protease with broad substrate specificity widely used in molecular diagnostic and nucleic acid preparation workflows. It efficiently degrades native proteins even in the presence of detergents, making it highly suitable for complex biological sample processing.

Structural studies show that Proteinase K belongs to the subtilisin family and contains a catalytic triad (Asp39–His69–Ser224). Its primary cleavage preference is peptide bonds adjacent to aliphatic and aromatic amino acids with blocked alpha amino groups.

Due to its strong proteolytic activity and broad compatibility, Proteinase K is commonly used in DNA/RNA extraction and sample pretreatment processes in molecular diagnostics.

Specification

Parameter	Specification
Appearance	White to off-white amorphous powder, lyophilized
Activity	≥30 U/mg
DNase	None detected
RNase	None detected
Nickase	None detected

Properties

Parameter	Specification	Figure
EC number	3.4.21.64 (Recombinant from Tritirachium album)
Molecular weight	29 kDa (SDS-PAGE)
Isoelectric point	7.81
Optimum pH	7.0–12.0	Fig. 1
Optimum temperature	65°C	Fig. 2
pH stability	pH 4.5–12.5 (25°C, 16h)	Fig. 3
Thermal stability	Below 50°C (pH 8.0, 30min)	Fig. 4
Storage stability	Over 90% activity stored at 25°C for 12 months	Fig. 5
Activators	SDS, urea
Inhibitors	Diisopropylfluorophosphate; phenylmethylsulfonylfluoride
Storage condition	Dry powder condition ≤8°C, valid for 36 months

Key Features

High Enzyme Activity

Engineered through direct enzyme evolution to deliver enhanced specific activity for efficient protein degradation.

High Salt Tolerance

Maintains activity in chaotropic environments such as guanidine hydrochloride and guanidine isothiocyanate.

Residue-Free Purity

Free from DNase, RNase, and Nickase contamination, ensuring high integrity of nucleic acid preparation.

Low Background Performance

Available mNGS-grade version is bioburden-free, supporting high-sensitivity molecular diagnostic workflows.

Applications

DNA & RNA Extraction

Efficiently digests proteins and nucleases during nucleic acid purification, improving DNA and RNA yield and purity.

Molecular Diagnostic Reagents

Suitable for PCR, qPCR, RT-PCR, and other nucleic acid-based diagnostic workflows requiring high-quality template preparation.

Genetic Diagnostic Kits

Used in sample pretreatment and extraction processes in genetic testing workflows.

Biopharmaceutical Processing

Helps remove protein impurities during preparation and purification of nucleic acid-based therapeutics and biological products.

Tissue & Cell Sample Preparation

Supports degradation of proteins in biological samples to enable extraction of non-protein components.

Performance Data

3-Year Room Temperature Stability

Both lyophilized powder and solution formulations retain stable activity when stored at room temperature for up to 36 months.

Excellent Guanidine Salt Tolerance

Demonstrates strong stability and activity in chaotropic salts such as guanidine hydrochloride and guanidine isothiocyanate, supporting harsh lysis conditions.

High Purity (DNase/RNase/Nickase Free)

No detectable DNase, RNase, or Nickase contamination, ensuring high-quality nucleic acid extraction performance.

FAQ

What is Proteinase K (PRK)?

Proteinase K is a stable serine protease with broad substrate specificity, commonly used to degrade proteins into short peptides during nucleic acid sample preparation.

What are the main product versions of PRK?

It is available in regular, NGS, and mNGS versions, and in both liquid and lyophilized powder formulations.

What are the key performance features of PRK?

It is DNase-free, tolerates high salt conditions, and is suitable for protein digestion in molecular biology workflows.