Neutral Protease, Protease, Neutral Proteinase, Peptidase, Endoprotease, 9040-76-0

Neutral Protease, Protease, Neutral Proteinase, Peptidase, Endoprotease, 9040-76-0

NEUTRAL PROTEASE

Neutral Protease / Protease (Neutral) / Neutral Proteinase / Peptidase / Endoprotease

• CAS Number: 9040-76-0

• EC Number: 232-752-2

• Enzyme Class: EC 3.4.24.27 / EC 3.4.21.14

SECTION 1: PRODUCT DEFINITION AND CHEMICAL IDENTITY

Description:
Neutral protease is an endopeptidase that hydrolyzes peptide bonds within protein molecules, breaking down proteins into smaller peptides and amino acids. Unlike acidic or alkaline proteases, neutral protease exhibits optimal activity at near-neutral pH (6.0-7.5). It is a metalloproteinase that requires zinc and calcium ions for catalytic activity and structural stability. Widely used in the food industry, particularly in meat processing (tenderization), cheese production (proteolysis during ripening), and production of protein hydrolysates. It is also extensively used in the pharmaceutical industry for digestive aid formulations and in the leather industry for bating processes.

SECTION 2: SYNONYMS AND OTHER NAMES

SECTION 3: ENZYMATIC STRUCTURE

3.1. Molecular Structure
Neutral protease is a metalloproteinase with a globular structure composed of a single polypeptide chain. The enzyme contains one zinc ion (Zn²⁺) in its active site, which is essential for catalytic activity, and several calcium ions (Ca²⁺) that contribute to structural stability. The active site is characterized by a characteristic HEXXH zinc-binding motif (Histidine-Glutamic acid-X-X-Histidine) where X represents any amino acid. The enzyme's three-dimensional structure includes α-helices, β-sheets, and random coil regions that create a cleft-shaped active site for substrate binding.

3.2. Catalytic Mechanism
Neutral protease catalyzes the hydrolysis of peptide bonds through a metal-dependent mechanism. The zinc ion in the active site polarizes the carbonyl group of the peptide bond, making it susceptible to nucleophilic attack by a water molecule. A glutamic acid residue acts as a general base, activating the water molecule for nucleophilic attack on the carbonyl carbon. The reaction proceeds through a tetrahedral intermediate, followed by collapse of the intermediate and release of the cleavage products. The enzyme's specificity is primarily determined by the amino acid residues surrounding the cleavage site.

3.3. Molecular Weight
25,000 - 50,000 Da (bacterial sources: ~35,000 Da; fungal sources: ~40,000 Da; animal sources: ~25,000 Da)

3.4. Basic Structural Properties

SECTION 4: PHYSICAL AND CHEMICAL PROPERTIES

SECTION 5: ENZYMATIC ACTIVITY AND REACTION

SECTION 6: REACTION MECHANISM

Neutral protease hydrolyzes peptide bonds through a metal-dependent catalytic mechanism involving the following steps:

6.1. Substrate Binding
The enzyme binds to the protein substrate through specific interactions between the active site and the amino acid residues surrounding the cleavage site. The binding is primarily driven by hydrophobic interactions and hydrogen bonding.

6.2. Catalytic Attack
The zinc ion (Zn²⁺) in the active site coordinates with the carbonyl oxygen of the peptide bond, polarizing the carbonyl group. A water molecule, activated by a glutamic acid residue acting as a general base, performs nucleophilic attack on the carbonyl carbon, forming a tetrahedral intermediate.

6.3. Bond Cleavage
The tetrahedral intermediate collapses, cleaving the peptide bond and releasing the two peptide products. The amino group of the peptide is protonated by the general acid (another glutamic acid residue), completing the hydrolysis reaction.

6.4. Product Release
The cleaved peptide fragments are released from the active site, and the enzyme returns to its resting state, ready for another catalytic cycle.

6.5. Factors Affecting Activity

• pH: Optimum activity at pH 6.0-7.5; activity drops significantly below pH 5.5 and above pH 8.0

• Temperature: Optimum at 45-55°C; activity drops at higher temperatures due to denaturation

• Metal Ions: Zinc and calcium ions are essential; chelators (EDTA) completely inhibit activity

• Substrate Concentration: Activity follows Michaelis-Menten kinetics

• Enzyme Concentration: Linear relationship between enzyme concentration and initial reaction rate

SECTION 8: REACTION EQUATIONS

8.1. Protein Hydrolysis (General Reaction)
Protein + n H₂O → Peptides + Amino Acids

8.2. Casein Hydrolysis
Casein + H₂O → Casein Peptides + Free Amino Acids

8.3. Gelatin Hydrolysis
Gelatin + H₂O → Gelatin Peptides + Free Amino Acids

8.4. Enzyme Inactivation (Thermal)
Neutral Protease (active) → Neutral Protease (inactive) (≥65°C, 15-30 minutes)

8.5. Enzyme Inhibition (Chelation)
Neutral Protease + EDTA → Enzyme-Metal Chelate Complex (inactive)

SECTION 9: PRODUCTION METHOD

Neutral protease is primarily produced through microbial fermentation.

Alternative Production Method (Recombinant): High-yield neutral protease production is possible using genetically modified Bacillus or Aspergillus species. Recombinant neutral proteases provide higher purity, specific activity, and controlled metal ion content.

SECTION 10: APPLICATIONS AND INDUSTRIAL USES

10.1. Meat Industry (Tenderization and Protein Modification)

Example Recipe – Meat Tenderization:

• Meat (beef, pork, poultry): 100 kg

• Neutral Protease: 10-50 g (depending on activity)

• Water (for spray application): 1-2 L

• Application temperature: 45-55°C

• Treatment time: 30-120 minutes

Dissolve neutral protease in water. Spray evenly over meat surface or inject into meat. Maintain temperature at 45-55°C. Allow enzyme to act for specified time. Cook or refrigerate as desired.

10.2. Cheese Production and Dairy Industry

Example Recipe – Accelerated Cheese Ripening:

• Cheese curd (freshly made): 100 kg

• Neutral Protease: 1-5 g (depending on activity)

• Application method: Surface spraying or mixing during curd processing

Dissolve neutral protease in sterile water. Apply to cheese surface or mix with curd. Incubate at 10-15°C during ripening. Regular sampling for texture and flavor evaluation.

10.3. Protein Hydrolysates and Functional Ingredients

10.4. Baking and Cereal Industry

10.5. Pharmaceutical and Nutraceutical Industry

10.6. Other Industrial Applications

SECTION 11: ALTERNATIVES AND COMPARISON

11.1. Acid Protease (EC 3.4.23) - Pepsin, Aspergillus acid protease

11.2. Alkaline Protease (EC 3.4.21.62) - Subtilisin, Bacillus protease

11.3. Papain (EC 3.4.22.2) - Plant Cysteine Protease

11.4. Bromelain (EC 3.4.22.32) - Plant Cysteine Protease

11.5. Ficin (EC 3.4.22.3) - Plant Cysteine Protease

SECTION 12: TOXICOLOGY AND SAFETY

12.1. Acute Toxicity

12.2. Regulatory Status

SECTION 13: GHS CLASSIFICATION (Powder Form)

Signal Word: Danger

Hazard Pictograms: GHS07 (Exclamation mark), GHS08 (Health Hazard)

Hazard Statements (H-Codes):

• H334: May cause allergy or asthma symptoms if inhaled

• H319: Causes serious eye irritation

• H335: May cause respiratory irritation

Safety Statements (Historical):

SECTION 14: PRECAUTIONARY STATEMENTS (P-CODES)

SECTION 15: FIRST AID MEASURES

SECTION 16: FIREFIGHTING MEASURES

SECTION 17: ACCIDENTAL RELEASE MEASURES

SECTION 18: STORAGE AND SHELF LIFE

SECTION 19: PACKAGING OPTIONS

SECTION 20: TRANSPORT INFORMATION

SECTION 21: ENVIRONMENTAL INFORMATION

SECTION 22: REGULATORY STATUS

SECTION 23: FREQUENTLY ASKED QUESTIONS (FAQ)

Q1: Is neutral protease safe for food applications?
A1: Yes. Neutral protease is classified as GRAS (Generally Recognized As Safe) by the FDA and approved as a food enzyme by EFSA. It is widely used in meat processing, cheese production, and protein hydrolysate manufacturing. However, the powder form may cause allergic reactions when inhaled, so appropriate personal protective equipment should be used.

Q2: What is the difference between neutral protease and acid or alkaline protease?
A2: Neutral protease has optimal activity at near-neutral pH (6.0-7.5). Acid proteases work best at pH 2.0-4.0, while alkaline proteases work at pH 8.0-11.0. Neutral protease is preferred for food applications where extreme pH conditions would damage the product, such as in meat tenderization and cheese ripening.

Q3: What is the role of metal ions in neutral protease activity?
A3: Neutral protease is a metalloproteinase that requires zinc (Zn²⁺) for catalytic activity and calcium (Ca²⁺) for structural stability. The zinc ion in the active site polarizes the peptide bond for hydrolysis, while calcium ions maintain the enzyme's three-dimensional structure. Chelating agents like EDTA completely inhibit the enzyme by removing these metal ions.

Q4: Is neutral protease suitable for vegan and halal products?
A4: Microbial (bacterial or fungal) sourced neutral proteases are suitable for vegan and halal certification. Since the product is produced from microorganisms such as Bacillus subtilis, it contains no animal ingredients. Animal-derived neutral proteases (pancreatic) are not suitable. Relevant certificates can be obtained from manufacturers.

Q5: What is the shelf life of neutral protease?
A5: In unopened original packaging, stored in a cool (4-25°C) and dry place away from direct sunlight, a shelf life of 12-24 months is recommended. For long-term storage, storing at 4°C minimizes activity loss. Calcium ions added to formulations improve stability.

Q6: How should neutral protease be stored?
A6: Store in a cool (preferably 4-25°C), dry, well-ventilated area in tightly closed containers. Moisture, high temperature (>40°C), and direct sunlight cause activity loss. Contact with metal chelators (EDTA) and heavy metals (copper, mercury) should be avoided.

Q7: What are the optimum working conditions for neutral protease?
A7: The optimum pH of neutral protease is between 6.0-7.5, and the optimum temperature is between 45-55°C. The enzyme is stable up to 55°C and rapidly inactivated above 65°C. It requires zinc and calcium ions for optimal activity. EDTA and other metal chelators completely inhibit the enzyme.

Q8: Why is neutral protease used in meat tenderization?
A8: Neutral protease hydrolyzes muscle proteins (myosin, actin, collagen, elastin) at near-neutral pH, which breaks down tough meat fibers and improves tenderness. Unlike acidic or alkaline proteases, neutral protease works under mild conditions that do not damage the meat's natural flavor and color. The enzyme is typically applied by injection or surface treatment before cooking.

Q9: How is neutral protease used in cheese production?
A9: In cheese production, neutral protease is added during cheese making or aging to accelerate proteolysis. This promotes flavor development, improves texture, and reduces ripening time. The enzyme breaks down casein proteins into smaller peptides and amino acids that contribute to cheese flavor. It is commonly used in enzyme-modified cheese production for creating concentrated cheese flavors.

Q10: What are the effects of inhaling neutral protease powder?
A10: Neutral protease powder, when inhaled, can cause allergic reactions, asthma-like symptoms, and respiratory tract irritation. Occupational asthma can develop upon repeated exposure to enzyme dust in food processing industries. Therefore, a dust mask (P2/P3) must always be used when handling the powder form, and local exhaust ventilation should be provided. Liquid formulations are safer alternatives.

SECTION 24: QUICK REFERENCE TABLE

SECTION 25: CRITICAL WARNINGS AND BEST PRACTICES

CRITICAL WARNINGS:

1. Dust Control and Respiratory Sensitization: Neutral protease powder can cause occupational asthma upon repeated exposure. Use local exhaust ventilation to prevent dust dispersion and always wear a dust mask (P2/P3). Liquid formulations are safer than powder forms.

2. Metal Ion Requirement: Neutral protease requires zinc (Zn²⁺) and calcium (Ca²⁺) for activity. Exposure to metal chelators (EDTA, EGTA) or agents that remove metal ions will completely inactivate the enzyme. Ensure processing water and ingredients do not contain chelating agents.

3. Activity Loss - Temperature: Neutral protease is rapidly and irreversibly inactivated above 65°C. Strictly maintain application temperatures within the optimum range (45-55°C). Temperature control is critical in meat processing and cheese production.

4. Activity Loss - pH: Neutral protease loses stability below pH 5.5 or above pH 8.5. Maintain application pH within the optimum range (6.0-7.5). Excessively acidic or basic conditions cause permanent enzyme inactivation.

5. Activity Loss - Heavy Metals: Mercury (Hg²⁺), copper (Cu²⁺), and other heavy metals inhibit neutral protease. Avoid these metals in equipment that comes into contact with the enzyme. Stainless steel, HDPE, or glass materials are preferred.

6. Food Grade: Only FDA/EFSA-approved food-grade neutral protease meeting specifications should be used in food applications. Industrial grade enzymes may contain impurities and are not suitable for human consumption.

7. Over-Hydrolysis Risk: Excessive enzyme dosage or prolonged treatment time may lead to over-hydrolysis, resulting in bitter peptides and undesirable texture. Carefully control enzyme dosage and reaction time based on specific application requirements.

8. Source Origin: Bacterial and fungal sources are suitable for vegan and halal products. Animal-derived neutral proteases (pancreatic) are not suitable for vegan applications and require additional certification for halal. Always verify source with the manufacturer.

BEST PRACTICE RECOMMENDATIONS:

• Storage: Store in a cool (4-25°C), dry, well-ventilated area in tightly closed containers. For long-term storage, +4°C (refrigeration) is recommended. Use within a short period after opening. Calcium-containing formulations have better stability.

• Handling: Use protective gloves, dust mask (P2/P3), and protective goggles. To prevent dust dispersion, preferably use liquid formulations. Prepare working solutions fresh for each application.

• Dosage: Calculate the correct dosage according to enzyme activity. Check enzyme activity for each batch. Start with low dosage and adjust based on results. Typical dosage ranges are 0.01-0.1% for meat tenderization and 0.001-0.01% for cheese applications.

• Enzyme Inactivation: Inactivate the enzyme by heat treatment (≥65°C, 15-30 minutes) at the end of the process to prevent over-hydrolysis. For meat products, cooking at higher temperatures will inactivate residual enzyme activity.

• Calcium Addition: Consider adding calcium ions (CaCl₂) to the application solution to improve enzyme stability and activity, particularly in purified water or systems with low mineral content.

• Quality Control: Perform activity testing for each batch. Maintain production and handling hygiene to prevent microbiological contamination. Monitor degree of hydrolysis during processing for consistent product quality.

• Atık Yönetimi: Dispose of enzyme and contaminated materials in accordance with local regulations. Do not discharge into sewers. Inactivate enzyme by heat treatment before disposal if released into wastewater.

LEGAL DISCLAIMER:

This Technical Data Sheet (TDS) is for informational purposes only and is prepared based on available technical data. The user is responsible for determining the suitability of the product for their specific application and for complying with all local, national, and international regulations. For complete safety, storage, handling, transport, waste, and regulatory compliance information, refer to the official Safety Data Sheet (SDS/MSDS) provided by the manufacturer/supplier. Neutral protease powder may cause sensitization when inhaled; appropriate protective equipment should be used. This document does not replace professional or medical advice.