ArtsAutosBooksBusinessEducationEntertainmentFamilyFashionFoodGamesGenderHealthHolidaysHomeHubPagesPersonal FinancePetsPoliticsReligionSportsTechnologyTravel

Biology - Protein Structure

Updated on February 9, 2013

Protein Structure

To make proteins lots of amino acids bond together in a specific sequence that is determined by the DNA.

The amino acid chains get longer and longer as more amino acids bond to it.

Parts of the amino acid chain will start to coil and pleat, the amount of coiling/pleating depends on the types of amino acids in the chain - the primary structure.

The coils and pleats are held together by numerous hydrogen bonds give the chain stability.

Once the whole chain is complete and a polypeptide is formed the coils and pleats will come together and give the molecule a 3D structure which is again determined by the primary structure of the protein and is held together by a number of different bonds.

There are 4 different levels of protein structure:

  • Primary
  • Secondary
  • Tertiary
  • Quaternary

Primary and Secondary Structure

  • The primary structure of a protein is the specific sequence of the amino acids that form it.
  • The secondary structure is when the chain of amino acids either forms an 'alpha helix' or a 'beta pleated sheet'. The secondary structure is defined by the patterns of hydrogen bonds between backbone amino and carboxyl groups. Hydrogen bonds, despite the fact that they're weak, hold the coils in place because there are so many of them overall it gives great stability.

Tertiary Structure

  • When the coils and pleats themselves coil or fold, it creates a 3D shape.
  • This shape is held together by many different bonds.
  • The tertiary structure is vital to it's function - for instance a hormone must be a specific shape to fit with the hormone receptor on the target cell.
  • Structural proteins such as collagen has proteins chains that are wound around each other, this provides strength.

Bonds Within Tertiary Structure

Disulfide Bonds:

  • The amino acid cysteine contains sulfur.
  • When two of cysteine molecules are close together disulfide bonds can form.

Ionic Bonds:

  • R-groups on the amino acids can sometimes carry a charge.
  • When oppositely charged amino acids are found close to each other, ionic bonds can form.

Hydrogen Bonds:

  • When positively charged groups are found next to negatively charged groups, hydrogen bonds form.

Different Protein Structures

The three-dimensional shape of a protein will either be in the 'globular' category or the 'fibrous' category.

Globular proteins tend to roll up into a compact ball like structures where any hydrophobic R-groups will turn inwards whilst the hydrophillic ones with turn outwards.

This makes it easier for the water molecules to cluster around them, thus making them water soluble molecules.

Globular proteins usually have metabolic roles and are found in plazma proteins, antibodies and in the blood of mammals (haemoglobin).

Fibrous proteins form fibres most of which have repetitive sequences of amino acids.

Fibrous proteins are insoluble in water and usually have structural roles and are found in things like collagen, bone and cartilage.

Proteins and Heat

When a protein is heated it is given kinetic energy and vibrates.

This causes some of the bonds within the tertiary structure of the molecule to break.

The bonds within the structure are not covalent and are therefore very weak and not much heat is needed to break them.

If enough heat is applied to the protein, the whole tertiary structure will unravel and uncoil and it will no longer be able to function - this is called denaturation.

If it is cooled the protein will not be able to reassemble itself.


    0 of 8192 characters used
    Post Comment

    No comments yet.


    This website uses cookies

    As a user in the EEA, your approval is needed on a few things. To provide a better website experience, uses cookies (and other similar technologies) and may collect, process, and share personal data. Please choose which areas of our service you consent to our doing so.

    For more information on managing or withdrawing consents and how we handle data, visit our Privacy Policy at:

    Show Details
    HubPages Device IDThis is used to identify particular browsers or devices when the access the service, and is used for security reasons.
    LoginThis is necessary to sign in to the HubPages Service.
    Google RecaptchaThis is used to prevent bots and spam. (Privacy Policy)
    AkismetThis is used to detect comment spam. (Privacy Policy)
    HubPages Google AnalyticsThis is used to provide data on traffic to our website, all personally identifyable data is anonymized. (Privacy Policy)
    HubPages Traffic PixelThis is used to collect data on traffic to articles and other pages on our site. Unless you are signed in to a HubPages account, all personally identifiable information is anonymized.
    Amazon Web ServicesThis is a cloud services platform that we used to host our service. (Privacy Policy)
    CloudflareThis is a cloud CDN service that we use to efficiently deliver files required for our service to operate such as javascript, cascading style sheets, images, and videos. (Privacy Policy)
    Google Hosted LibrariesJavascript software libraries such as jQuery are loaded at endpoints on the or domains, for performance and efficiency reasons. (Privacy Policy)
    Google Custom SearchThis is feature allows you to search the site. (Privacy Policy)
    Google MapsSome articles have Google Maps embedded in them. (Privacy Policy)
    Google ChartsThis is used to display charts and graphs on articles and the author center. (Privacy Policy)
    Google AdSense Host APIThis service allows you to sign up for or associate a Google AdSense account with HubPages, so that you can earn money from ads on your articles. No data is shared unless you engage with this feature. (Privacy Policy)
    Google YouTubeSome articles have YouTube videos embedded in them. (Privacy Policy)
    VimeoSome articles have Vimeo videos embedded in them. (Privacy Policy)
    PaypalThis is used for a registered author who enrolls in the HubPages Earnings program and requests to be paid via PayPal. No data is shared with Paypal unless you engage with this feature. (Privacy Policy)
    Facebook LoginYou can use this to streamline signing up for, or signing in to your Hubpages account. No data is shared with Facebook unless you engage with this feature. (Privacy Policy)
    MavenThis supports the Maven widget and search functionality. (Privacy Policy)
    Google AdSenseThis is an ad network. (Privacy Policy)
    Google DoubleClickGoogle provides ad serving technology and runs an ad network. (Privacy Policy)
    Index ExchangeThis is an ad network. (Privacy Policy)
    SovrnThis is an ad network. (Privacy Policy)
    Facebook AdsThis is an ad network. (Privacy Policy)
    Amazon Unified Ad MarketplaceThis is an ad network. (Privacy Policy)
    AppNexusThis is an ad network. (Privacy Policy)
    OpenxThis is an ad network. (Privacy Policy)
    Rubicon ProjectThis is an ad network. (Privacy Policy)
    TripleLiftThis is an ad network. (Privacy Policy)
    Say MediaWe partner with Say Media to deliver ad campaigns on our sites. (Privacy Policy)
    Remarketing PixelsWe may use remarketing pixels from advertising networks such as Google AdWords, Bing Ads, and Facebook in order to advertise the HubPages Service to people that have visited our sites.
    Conversion Tracking PixelsWe may use conversion tracking pixels from advertising networks such as Google AdWords, Bing Ads, and Facebook in order to identify when an advertisement has successfully resulted in the desired action, such as signing up for the HubPages Service or publishing an article on the HubPages Service.
    Author Google AnalyticsThis is used to provide traffic data and reports to the authors of articles on the HubPages Service. (Privacy Policy)
    ComscoreComScore is a media measurement and analytics company providing marketing data and analytics to enterprises, media and advertising agencies, and publishers. Non-consent will result in ComScore only processing obfuscated personal data. (Privacy Policy)
    Amazon Tracking PixelSome articles display amazon products as part of the Amazon Affiliate program, this pixel provides traffic statistics for those products (Privacy Policy)