Peptide Biochemistry
Jul 31, 2024
7 min read
Written by Johnathon Anderson, Ph.D., a research scientist specializing in regenerative medicine and serving as an Associate Professor at the University of California Davis School of Medicine
What Is The Structure Of A Peptide?
Peptides’ structure consists of short chains of amino acids, generally composed of 2 to 50 amino acids, formed by a condensation reaction that links them through covalent bonds. These chains serve as the primary building blocks for proteins, with each amino acid joined sequentially by peptide bonds to form an extended peptide chain.
In peptide formation, each amino acid is called a "residue," signifying what remains after water is lost in the condensation reaction. Structurally, amino acids feature an amino group and a carboxyl-terminal group, which are fundamental for protein formation.
What Are The General Steps In Peptide Synthesis?
The 3 general steps in peptide synthesis are:
Deprotection Step: This preparatory phase readies an amino acid for chain elongation.
Activation: The amino acid undergoes activation, often through reagents targeting the carboxylic acid, facilitating the coupling reaction.
Coupling Reaction: This final stage links amino acids into a peptide chain with functional potential.
These steps repeat, allowing researchers to extend the peptide chain as needed to achieve the desired sequence and length. The peptide bonds created are robust, resisting conditions such as high temperatures and urea concentrations, which typically denature proteins.
How Does A Peptide Biochemistry Determine Its Rigidity?
Peptide biochemistry determines how rigid it is based on how many double bonds it contains. Peptide bonds, formed in the ribosomal active site, exhibit partial double-bond characteristics, imparting them with rigidity and planarity. This rigidity arises from the shorter, stronger nature of double bonds, which also limits the rotation around the peptide bond. However, bonds between other carbon atoms in the chain are free to rotate, allowing peptides to adopt various configurations and structural isomers.
What Do Peptides Do In The Body?
Peptides have many functions in the body and can regulate blood pressure, exhibit antimicrobial activity, and possess anti-inflammatory and antioxidant properties. Such peptides are of significant interest in the pharmaceutical sector for their therapeutic potential in mimicking endogenous compounds to modulate cellular functions and biochemical processes.
What Are The Steps In Peptide Translation?
Initiation: mRNA binds to a small ribosomal subunit, guided by specific nucleotide sequences (e.g., Kozak sequences).
Elongation: The ribosome's large subunit accommodates amino acids in three sites (A, P, and E), with tRNA and aminoacyl-tRNA synthetase facilitating bond formation.
Termination: The peptide chain is completed and undergoes modifications.
Once synthesized, peptides may undergo post-translational modifications (e.g., methylation, phosphorylation) to refine their function and bioactivity. After initial formation, peptides are packaged and cleaved as they transition into their final active forms, with some destined to serve as preprohormones or prohormones before being transported to their functional sites.
How Are Peptide Therapies Manufactured?
Peptide therapies are manufactured using a process known as Solid-Phase Peptide Synthesis (SPPS). This method allows for rapid assembly of peptide chains, enabling precision control over amino acid sequences and extensive customization for therapeutic research applications.
What Are The Key Peptide Hormone Families In The Body?
The key peptide hormone families include:
Pro-opiomelanocortin (POMC) Derivatives: A precursor for various active peptides, including MSH and ACTH, influencing pigmentation and adrenal function.
Oxytocin and ADH: Nonapeptides crucial for social bonding and water retention, packaged with neurophysins for transport.
Insulin and IGF-1: Peptides managing glucose homeostasis and cellular growth, featuring multiple disulfide bonds.
Glucagon and Secretin: Essential in metabolic regulation, stimulating responses to maintain energy balance and neutralize gastric acid, respectively.
How Do Peptides Help The Body?
Peptides help the body in the following ways:
A] Peptides in Infection Control
Antimicrobial peptides (AMPs) form a critical aspect of the innate immune system, produced by various tissues, including the skin, neutrophils, and mast cells. AMPs such as defensins and cathelicidins are cationic and target microbial cell membranes, providing a defense against infection. Additionally, some bacteria can develop resistance mechanisms, proteolytically cleaving peptides to survive within host tissues.
B] Therapeutic Applications and Imaging
Synthetic peptides are advancing as imaging probes due to their selective receptor-binding capabilities. Designed to mimic endogenous peptides, these molecules allow precise tumor identification and have applications in PET, MRI, and other imaging modalities, offering targeted diagnostics and potential therapeutic interventions.
C] Wound Healing and Skin Inflammation
Peptides such as syndecan promote wound healing by activating growth factors and aiding tissue repair. In chronic skin conditions, disrupted peptide expression may either suppress or exacerbate inflammatory responses, influencing diseases like atopic dermatitis and rosacea.
D] Natriuretic Peptides
Cardiac-produced natriuretic peptides, such as ANP and BNP, play roles in cardiovascular homeostasis, exhibiting protective effects like vasodilation and modulation of blood pressure. These peptides have inspired therapeutic developments for cardiovascular conditions.
Summary
Peptides are vital components in biochemical and physiological processes, from cellular communication to immune defense and therapeutic potential. As biochemical sciences evolve, synthetic and bioactive peptides continue to play an increasingly prominent role in medicine and research, highlighting the complexity and utility of these molecular building blocks.
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What to Look for in Premium Peptides
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Jul 31, 2024
7 min read
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