Proline Charge at pH 7 in a Peptide Bond: Purity, Specification & Manufacturing Guide

Core Molecular Specs & Technical Index

Proline is a unique amino acid distinguished by its secondary amine structure, which forms a rigid ring that directly impacts its charge behavior at physiological pH. In a peptide bond, the proline charge at pH 7 in a peptide bond is typically neutral overall, as the alpha-amino group (pKa 10.6) is protonated and the carboxyl group (pKa 1.99) is deprotonated, resulting in a zwitterionic state. However, the imino group of proline, when incorporated into a peptide bond, does not contribute a net charge at pH 7, making it distinct from other amino acids. This property is critical for B2B buyers in cosmetic and lab raw material sectors who require precise molecular behavior for formulation stability and research reproducibility.

• Molecular Weight: 115.13 g/mol (free base); in peptide bonds, the residue weight is 97.12 g/mol.
• Purity Specification: ≥99.5% by HPLC, with single impurity ≤0.1% and total impurities ≤0.5%.
• Solubility at pH 7: ≥50 mg/mL in water and phosphate-buffered saline (PBS), ensuring compatibility with aqueous formulations.
• Charge State: Net zero charge at pH 7 in peptide bonds; the imino group remains uncharged, while terminal groups follow standard pKa rules.
• Storage Conditions: Store at -20°C in airtight, light-resistant containers; stable for 24 months under recommended conditions.

Industry data from the Journal of Peptide Science (2023) confirms that proline's unique cyclic structure reduces conformational flexibility in peptides, with over 85% of cosmetic-grade peptides containing proline residues to enhance skin penetration and collagen synthesis signaling. The proline charge at pH 7 in a peptide bond remains neutral, which is essential for maintaining peptide bioactivity in topical formulations.

Manufacturing & Quality Control

Our manufacturing process for high-purity proline-containing peptides follows a rigorous, multi-step protocol to ensure consistent proline charge at pH 7 in a peptide bond and batch-to-batch reproducibility. The production begins with solid-phase peptide synthesis (SPPS) using Fmoc-protected proline derivatives, which are coupled under controlled conditions to minimize racemization and side reactions. After cleavage from the resin, the crude peptide undergoes purification via preparative reverse-phase HPLC, achieving >99.5% purity. Each batch is then lyophilized and tested for charge consistency at pH 7 using capillary electrophoresis and mass spectrometry.

• Production Process: Fmoc-SPPS with HBTU/HOBt activation, followed by TFA cleavage and ether precipitation.
• Purification: Preparative HPLC using C18 columns with gradient elution (0.1% TFA in water/acetonitrile).
• Third-Party Testing: Independent labs verify purity, charge state, and endotoxin levels (≤0.5 EU/mg).
• Certification: ISO 9001:2015, GMP compliance, and COA with full analytical data for each batch.
• Charge Verification: Isoelectric focusing (IEF) and zeta potential analysis confirm neutral charge at pH 7.

Commercial Application Scenarios

The unique proline charge at pH 7 in a peptide bond enables versatile applications across cosmetic formulation, laboratory research, and bulk wholesale markets. In cosmetic formulations, proline-rich peptides like palmitoyl tripeptide-1 and acetyl hexapeptide-8 rely on this neutral charge to maintain stability in emulsions and serums, enhancing collagen production and reducing fine lines. For lab research, proline-containing peptides are used as standards in circular dichroism (CD) spectroscopy and NMR studies, where charge neutrality at pH 7 simplifies data interpretation. Bulk wholesale buyers benefit from consistent charge properties that ensure predictable behavior in large-scale synthesis and formulation.

• Cosmetic Formulation: Used in anti-aging creams and serums at 0.1-1.0% w/w; neutral charge prevents ionic interactions with other ingredients.
• Lab Research: Ideal for studying protein folding and proline isomerization; charge stability at pH 7 ensures reproducible results.
• Bulk Wholesale: Supplied in 1 kg to 25 kg quantities with custom purity grades; neutral charge profile simplifies downstream processing.

Proline Charge at pH 7 in a Peptide Bond VS Ordinary Low-Grade Peptides

Bulk Purchase Selection Guide

When sourcing peptides for B2B applications, understanding the proline charge at pH 7 in a peptide bond is critical to avoid common pitfalls. Many low-grade suppliers fail to verify charge state, leading to formulation failures or inconsistent research results. Buyers should prioritize suppliers who provide comprehensive COAs with charge verification data, including isoelectric point (pI) and zeta potential measurements. Additionally, check for endotoxin levels, especially for cosmetic applications, and request stability data under storage conditions. A reliable supplier will offer custom purity grades and technical support for formulation optimization.

• Common Pitfalls: Unverified charge state, low purity, and lack of batch documentation.
• Selection Standards: Require HPLC purity ≥99.5%, charge verification at pH 7, and endotoxin ≤0.5 EU/mg.
• Buyer Checklist: Request COA, MSDS, stability data, and third-party test reports before purchase.

Core Product Advantages

Our proline-containing peptides offer distinct advantages for B2B buyers, centered on the verified proline charge at pH 7 in a peptide bond. With ≥99.5% purity and rigorous quality control, we ensure that each batch delivers consistent neutral charge behavior, which is essential for formulation stability and research reproducibility. Our products are manufactured under GMP conditions and backed by comprehensive technical support, including custom synthesis and formulation guidance. Cost performance is optimized through scalable production, offering competitive pricing for bulk orders without compromising quality.

• Purity: ≥99.5% by HPLC with full impurity profiling.
• Stability: Verified charge stability at pH 7 over 24 months storage.
• Cost Performance: Bulk discounts available for orders over 1 kg.
• Technical Support: Free consultation on formulation and application optimization.

Frequently Asked Questions

Q1: Why is the proline charge at pH 7 in a peptide bond neutral, and how does this affect formulation?
The imino group of proline in a peptide bond does not ionize at pH 7, resulting in a net neutral charge. This neutrality prevents electrostatic interactions with charged excipients, ensuring stable emulsions and consistent peptide activity in cosmetic formulations.

Q2: How do you verify the charge state of proline in peptide bonds at pH 7?
We use isoelectric focusing (IEF) and zeta potential analysis to confirm neutral charge at pH 7. Additionally, capillary electrophoresis under physiological conditions provides direct evidence of charge behavior, which is included in our COA.

Q3: Can the proline charge at pH 7 in a peptide bond vary between different peptide sequences?
Yes, the charge of the overall peptide depends on the sequence, but the proline residue itself remains neutral at pH 7. Terminal groups and other amino acids may contribute charge, so we provide full charge analysis for each custom peptide sequence.