Α helix The peptide bond with proline presents unique characteristics that significantly influence protein structure and function. Unlike other amino acids, proline's cyclic side chain affects peptide bond formation, conformation, and subsequent biological processes. Understanding these peculiarities is crucial for comprehending protein folding, stability, and the activity of proline-rich peptides作者：G Vanhoof·1995·被引用次数：624—When present inside an a-helix,prolinealso sterically prevents the amide nitrogen of its C-terminal neighbor from making a hydrogenbondwith a carbonyl in..
Proline is an amino acid that stands apart due to its cyclic structure, where the amino group is incorporated into the side chain, forming a secondary amine. This structural feature has profound implications for the peptide bond it forms. When proline is part of a peptide chain, the bond formed at its C-terminus (the bond between the carboxyl group of proline and the amino group of the next amino acid) is unique. This secondary amine means proline lacks a hydrogen atom on its alpha-amino group, which prevents it from acting as a hydrogen bond donor in stabilizing secondary structures like alpha-helices or beta-sheets作者：D Asakawa·2024·被引用次数：1—Theprolineeffect can be explained bypeptidecation radical formation and subsequent proton migration from the δ-carbon in the Pro residue..
Furthermore, the peptide bond involving proline exhibits a higher propensity to exist in the *cis* conformation compared to peptide bonds involving other amino acids, which predominantly favor the *trans* conformation. This *cis/trans* isomerization around the peptide bond is a slow process, especially when proline is involved, acting as a kinetic bottleneck in protein folding.作者：G Vanhoof·1995·被引用次数：624—When present inside an a-helix,prolinealso sterically prevents the amide nitrogen of its C-terminal neighbor from making a hydrogenbondwith a carbonyl in. This isomerization capability allows proline to introduce kinks and turns in peptide chains, conferring unique conformational constraints.作者：E Masoumzadeh·2024·被引用次数：6—Prolineisomerization is widely recognized as a kinetic bottleneck in protein folding, amplified for proteins rich in Pro residues.
The presence of proline significantly impacts the rate of peptide bond formation during protein synthesis. Research indicates that proline incorporates into newly forming polypeptide chains at a considerably slower rate than many other amino acids. This slower incorporation can lead to ribosome stalling, a phenomenon that can be amplified in proteins rich in proline residues. This kinetic impediment is largely attributed to the unique chemical nature of the proline peptide bond and its associated isomerization.
The *cis/trans* isomerization of the proline peptide bond is a critical step in the folding pathways of many proteins.作者：G Vanhoof·1995·被引用次数：624—When present inside an a-helix,prolinealso sterically prevents the amide nitrogen of its C-terminal neighbor from making a hydrogenbondwith a carbonyl in. While other peptide bonds rapidly adopt their preferred *trans* conformation, the proline peptide bond's ability to exist in both states and its slow isomerization rate can delay the attainment of the native protein structure.Proline - Amino Acids This characteristic is particularly pronounced in proline-rich signaling peptides and can influence the biological processing and activity of these molecules.Proline Derivatives and Analogs
The *cis* and *trans* conformations of the proline peptide bond are not merely theoretical possibilities; they have tangible effects on peptide and protein structure. While the *trans* conformation is generally more stable for most amino acid peptide bonds, proline's cyclic structure allows it to readily adopt and stabilize the *cis* conformation. This ability to exist in both states contributes to proline's role as a "structure breaker" or, more accurately, a "conformation inducer," often causing kinks or bends in the polypeptide backbone.Slow peptide bond formation by proline and other N- ...
These conformational preferences are not uniform across all proline-containing peptides. The specific amino acid sequence adjacent to the proline residue can influence the *cis/trans* ratio of the proline peptide bond. This sequence-dependent behavior means that the structural impact of proline can be fine-tuned by its surrounding amino acids, allowing for diverse roles in protein architectureWhat is the structure of proline peptide bond?.
The proline peptide bond also exhibits distinct chemical reactivity. For instance, aspartyl-proline peptide bonds have been observed to be particularly susceptible to hydrolysis under acidic conditions, a phenomenon where other aspartyl bonds remain stableAnomalous cleavage of aspartyl-proline peptide bonds .... This anomalous cleavage highlights the unique lability of proline-containing peptide bonds under certain chemical environments.
Furthermore, specific chemical cleavage methods have been developed to target and break peptide bonds adjacent to proline residues. This targeted cleavage can be a useful tool in biochemical research for analyzing peptide sequences and understanding the structural roles of proline.Peptide bond formation is also slow between an incoming tRNA and a chain ending in proline; with the creation of proline-proline bonds slowest of all.
Proline's unusual properties make it a vital component in many biologically important peptides and proteins. Its ability to induce specific turns and kinks is crucial for the proper three-dimensional folding of proteins, influencing their interactions with other molecules and their overall function. Proline-rich motifs are found in various signaling peptides and structural proteins, where their conformational constraints play essential rolesPeptide bond formation is also slow between an incoming tRNA and a chain ending in proline; with the creation of proline-proline bonds slowest of all.. The *cis/trans* isomerization of proline peptide bonds is also implicated in various biological processes, including enzyme catalysis and signal transduction, where it can act as a regulatory switchProline Peptide Bond Isomerization in Ubiquitin Under ....
In summary, the peptide bond with proline is a subject of significant interest due to its unique structural, kinetic, and chemical properties. Its influence on peptide bond formation rate, conformational flexibility, and susceptibility to cleavage makes it a critical determinant of protein structure and function.
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