Main Difference – Alpha Helix and Beta Pleated Sheet

Alpha helix and beta plates are two different second structures of protein. Alpha helix is a right handed-coiled or spiral condevelopment of polypeptide chains. In alpha helix, every backbone N-H team donates a hydrogen bond to the backbone C=O team, which is put in 4 residues prior. Here, hydrogen bonds show up within a polypeptide chain in order to develop a helical framework. Beta sheets consist of beta strands connected laterally by at least two or 3 backbone hydrogen bonds; they form a mostly twisted, pleated sheet. In comparison to the alpha helix, hydrogen bonds in beta sheets create in between N-H groups in the backbone of one strand and C=O teams in the backbone of the nearby strands. This is the main difference between Alpha Helix and also Beta Pleated Sheet.

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What is an Alpha Helix

Proteins are consisted of of polypeptide chains, and also they are separated into a number of categories such as main, secondary, tertiary, and also quaternary, relying on the form of a folding of the polypeptide chain. α-helices and beta-pleated sheets are the two many typically encountered additional structures of a polypeptide chain.

Alpha-helical framework of proteins forms because of hydrogen bonding between its backbone amide and also carbonyl groups. This is a best handed coil, which typically contain 4 to 40 amino acid residues in the polypeptide chain. The following figure illustrates the structure of alpha helix.


Hydrogen bonds develop between an N-H team of one amino residue via a C=O group of another amino acid, which is placed in 4 residues previously. These hydrogen bonds are crucial to producing the alpha helical structure, and eextremely finish revolve of the helix has actually 3.6 amino residues.

Amino acids whose R-groups are also huge (i.e. tryptophan, tyrosine) or also tiny (i.e. glycine) destabilize α-helices. Proline additionally destabilizes α-helices because of its irconsistent geometry; its R-group bonds back to the nitrogen of the amide group, and also reasons steric hindrance. In enhancement, the lack of a hydrogen on Proline’s nitrogen avoids it from participating in hydrogen bonding. Apart from that, the stability of alpha helix counts on the dipole minute of the entire helix, which is brought about as a result of individual dipoles of C=O groups connected in hydrogen bonding. Stable α-helices generally finish through a charged amino acid to neutralize the dipole minute.


A Hemoglobin molecule, which has actually four heme-binding subunits, each made mainly of α-helices.

What is Beta Pleated Sheet

Beta pleated sheets are an additional kind of protein secondary framework. Beta sheets consist of beta strands associated laterally by at least two or three backbone hydrogen bonds, creating a primarily twisted, pleated sheet. Generally, a beta strand also consists of 3 to 10 amino acid residues, and also these strands are arranged adjacent to various other beta strands while forming substantial hydrogen bond netoccupational. Here, N-H groups in the backbamong one strand create hydrogen bonds with the C=O teams in the backbamong the adjacent strands. Two ends of the peptide chain have the right to be assigned to the N- terminus and C- terminus in order to show the direction. N- terminus shows one end of the peptide chain, where free amine group is obtainable. Similarly, C- terminus reexisting the other terminal of peptide chain, wright here cost-free carboxylic team is available.

Adjacent β strands can form hydrogen bonds in antiparallel, parallel, or mixed arrangements. In the anti-parallel plan, N-terminus of one stand is surrounding to the C- terminus of following stand. In a parallel setup, N- terminus of adjacent strands are oriented in the exact same direction. The adhering to number illustrates the framework and hydrogen bonding pattern of parallel and also anti-parallel beta strands.


a) anti parallelb) parallel

Difference Between Alpha Helix and also Beta Pleated Sheet


Alpha Helix: Alpha Helix is a right-handed coiled rod-prefer structure.

Beta Pleated Sheet: Beta sheet is a sheet-like structure.


Alpha Helix: Hydrogen bonds develop within the polypeptide chain in order to produce a helical structure.

Beta Pleated Sheet: Beta sheets are created by linking 2 or even more beta strands by H bonds.


Alpha Helix: Alpha helix has actually n + 4 H-bonding plan. i.e. Hydrogen bonds create in between N-H group of one amino residue through C=O group of another amino acid, which is put in 4 residues previously.

Beta Pleated Sheet: Hydrogen bonds are developed in between the surrounding N-H and also C=O groups of surrounding peptide chains.

-R group

Alpha Helix: -R teams of the amino acids are oriented outside of the helix.

Beta Pleated Sheet: -R teams are directed to both inside and also external of the sheet. 


Alpha Helix: This can be a single chain.

Beta Pleated Sheet: This cannot exist as a solitary beta strand; there are should be two or more.


Alpha Helix: This has just one form.

Beta Pleated Sheet: This have the right to be parallel, anti-parallel or mixed.


Alpha Helix: 100o rotation, 3.6 residues per rotate and 1.5 Ao increase from one alpha carbon to the second 

Beta Pleated Sheet: 3.5 Ao rise between residues

Amino Acid

Alpha Helix: Alpha helix prefers the amino acid side chains, which deserve to cover and also protect the backbone H-bonds in the core of the helix.Beta Pleated Sheet: The extfinished framework leaves the maximum room free for the amino acid side chains. As such, amino acids through big bulky side chains like beta sheet structure.

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Alpha Helix: Alpha helix prefers Ala, Leu, Met, Phe, Glu, Gln, His, Lys, Arg amino acids. 

Beta Pleated Sheet: Beta sheet prefers Tyr, Trp, (Phe, Met), Ile, Val, Thr, Cys.


Image Courtesy:

“Alpha Helix Protein Structure” via Commons Wikimedia

“Hempglobin molecule” By Zephyris at the English language Wikipedia (CC BY-SA 3.0) through Commons Wikimedia 

“Parellel and also Antiparellel” by Fvasconcellos – Own work.Created by uploader upon research by Opabinia regalis., (Public Domain) by means of Commons Wikimedia