Description

Technical Parameters

Introduction

peptides

product-1400-1400

Products Description

#### **1. Overview**

Botox (botulinum toxin) is a neurotoxin secreted by Clostridium botulinum (*Clostridium botulinum*), which achieves muscle relaxation by blocking the release of acetylcholine at the neuromuscular junction. Among them, "191aa" refers to a polypeptide fragment composed of 191 amino acids, which is usually an engineered modified toxin core functional region (such as the active fragment of the light chain or heavy chain), with high specificity and low immunogenicity. Botox 191aa polypeptides are widely used in the fields of medicine, beauty and scientific research, and their classification and characteristics vary depending on the structure, function and formulation process.

#### **2. Main classification of Botox 191aa polypeptides**

Based on molecular structure, modification method and use, Botox 191aa polypeptides can be divided into the following categories:

##### **1. Natural Botox 191aa polypeptides**

- **Source**: Unmodified natural botulinum toxin hydrolyzed fragments.

- **Advantages**: retains original biological activity, rapid action (onset time 24-72 hours), clear efficacy.

- **Physical and chemical properties**:

- **Molecular weight**: about 19-21 kDa (depending on the specific sequence).

- **Stability**: sensitive to heat (needs to be stored below -20°C), easily degraded by proteases.

- **Solubility**: soluble in neutral buffer (such as PBS), isoelectric point (pI) is about 5.5-6.0.

- **Color**: lyophilized powder is white loose solid, and colorless transparent liquid after reconstitution.

##### **2. Polyethylene glycol (PEG) modified type**

- **Structure**: PEG molecules are connected by covalent bonds to increase hydrophilicity and molecular weight.

- **Advantages**:

- **Extended half-life**: PEGylation reduces renal clearance and the duration of action is extended to 4-6 months.

- **Reduced immunogenicity**: shielding antigen epitopes and reducing antibody production.

- **Physical and chemical properties**:

- **Molecular weight**: 30-50 kDa (depending on the length of the PEG chain).

- **Stability**: Improved heat resistance (can be stored at 4°C for a short period of time), enhanced resistance to enzymatic hydrolysis.

- **Color**: Lyophilized powder is slightly yellow (PEG oxidation may cause the color to deepen).

##### **3. Lyophilized preparations and prefilled liquid preparations**

- **Lyophilized preparations**:

- **Advantages**: Good long-term stability (shelf life 2-3 years), easy to transport.

- **Physical and chemical properties**: Need to be reconstituted for use, pH 6.8-7.2 after reconstitution.

- **Color**: White crystalline powder.

- **Prefilled liquid**:

- **Advantages**: Ready to use, avoid reconstitution errors.

- **Physical and chemical properties**: Contains stabilizers (such as human albumin, sodium chloride), pH 7.0±0.3.

- **Color**: Colorless or light yellow clear liquid.

##### **4. Composite peptides (targeted modified type)**

- **Structure**: Introducing targeted peptides through genetic engineering (such as targeting neuron surface receptors).

- **Advantages**:

- **Precise delivery**: Reduce nonspecific diffusion and reduce side effects (such as facial stiffness).

- **Enhanced penetration**: Improved efficiency of penetrating the stratum corneum or blood-brain barrier.

- **Physical and chemical properties**: The molecular weight may increase to more than 25 kDa, and the solubility depends on the modified group.

- **Color**: Depending on the modified component, it may appear as a milky white suspension.

#### **3. In-depth analysis of physical and chemical properties**

1. **Thermal stability**:

- The natural type has an active half-life of only a few hours at 25°C, and the PEG-modified type can be extended to several days.

- The freeze-dried preparation can be stored at -20°C for 3 years through vacuum dehydration, with an activity loss of <5%.

2. **pH sensitivity**:

- The optimum pH is 6.5-7.5. Acidic environment (pH < 5) causes conformational changes and loss of activity.

3. **Solubility and excipients**:

- The commonly used solvent is water for injection containing 0.9% NaCl. Adding gelatin or albumin can reduce adsorption losses.

#### **4. Scientific significance of color change**

- **White lyophilized powder**: a sign of high purity (protein aggregation is amorphous structure).

- **Yellow liquid**: may indicate oxidation (such as oxidation of methionine residues) or degradation, and quality inspection is required to confirm activity.

- **Milky suspension**: liposome encapsulation or complex aggregation exists, and it needs to be shaken before use.

#### **5. Comparison of core advantages**

| **Category** | **Advantages** | **Limitations** |

|----------------|--------------------------|-------------------------|

| Natural type | High activity, low cost | Poor stability, need to be stored at low temperature |

| PEG modified type | Long-acting, low immunogenicity | Large molecular weight, slow diffusion |

| Targeted modified type | Precision treatment, few side effects | Complex production process, high price |

#### **6. Expansion of application areas**

1. **Medical field**:

- Chronic migraine (FDA approved), spasmodic torticollis, hyperhidrosis.

2. **Beauty field**:

- Dynamic wrinkles (brow wrinkles, crow's feet), face slimming (masseter muscle reduction).

3. **Scientific research field**:

- Research on neurotransmitter release mechanism, development of drug delivery system.

#### **7. Quality control and safety**

- **Quality control indicators**: HPLC purity > 98%, endotoxin < 5 EU/mg.

- **Safety**: Dose-dependent side effects (local edema, headache), severe allergic reactions are rare (<0.1%).

#### **8. Future development direction**

- **Oral preparation development**: Intestinal absorption through nanocarriers.

- **Intelligent modification**: Light-controlled or temperature-controlled release of peptides to achieve precise start-stop effects.

#### **Conclusion**

Botox 191aa peptide continues to expand its application boundaries through structural optimization and dosage form innovation. In the future, with the advancement of gene editing and delivery technology, its accuracy and safety will be further improved, becoming a model of innovation in multidisciplinary cross-border.