structure of proteins Watch

shenayamaria
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explain how the primary structure of an enzyme determines its 3d structure and properties
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macpatgh-Sheldon
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Hi btw there was a singer before your time (Shanaya Twain) - actually before my time too! Your mum/dad will know (sorry, I know this is not a Q about music!)

Ok let us take it step by step:
You know that proteins are made of of chains of amino acids, and amino acids have a -COOH (acidic) and an -NH2 (basic) groups - some amino acids have more than one of these e.g. aspartic acid has an extra -COOH (acidic a.a.) and histidine has an extra -NH2 (basic a.a.). With me so far?

PRIMARY STRUCTURE = which a.a.-s ,make up the enzyme and in what order - yes? So the 3D structure will depend on the hydrogen bonding between -H and either -O or -N etc. (the no and location of these will depend on the above [in bold]) Also suphur containing amino acids (cystine and methionine) will form disulphide bridges between peptide chains [or parts of one chain] - and other things - check print in italics below - these factors will determine the 3-D folding of the protein and hence the shape of the active site of the enzyme - yeah?

Read up a bit more online on secondary and tertiary protein structure.........................and..... ................................ ................................ ....you are done and dusted!

Now you can sing "Yesterday" - ask dad/mum again! also ask her to give you a good dinner to fuel your "midnight oil" when you sit to study again!

Good luck!

M
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thedecorator33
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Well, the primary structure of a protein is just the sequence of amino acids in the polypeptide chain(s).

The tertiary structure of a protein is the overall 3D shape of the protein - This 3D shape forms due to hydrogen bonds, disulfide bonds, ionic bonds etc.

So depending on what amino acids you have in the primary structure of the protein, this will affect the tertiary structure.

For instance, if you have lots of amino acids which contain Sulfur atoms (e.g. cysteine amino acids) then lots of disulphide bonds will form between the atoms containing the sulfur atoms. These disulphide bonds affect the way in which the protein folds to form the final 3D shape.

The 3D shape of the enzyme will affect its properties because the 3D shape affects the shape of the active site, meaning that only substrates with complementary shapes to the active site will be able to fit into it.
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bonie1020
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(Original post by shenayamaria)
explain how the primary structure of an enzyme determines its 3d structure and properties
The primary structure of a protein is the specific number and sequence of amino acids in a polypeptide chain. This will form one of two secondary structures held together by hydrogen bonds; they either fold to form a Beta Pleated Sheet or an Alpha helix.

The next stage of folding determines its 3D structure. An amino acid has an R group which is specific to each amino acid, as a result, it interacts with other R groups forming different types of bonds eg disulphide, ionic, covalent. Therefore, the Alpha helix or beta pleated sheet will fold and their R groups form these bonds which hold them in their precise 3D structure which is different for each primary structure.

As for its properties, its tertiary structure will be a compact globular protein with a specifically shaped active site which can form the enzyme-substrate complex with the complementary substrate. Its primary structure is crucial to the shape of the active site as different R groups produce different bonds which change the overall shape and therefore the shape of the active site.

I hope this helps.
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