Describe the general structure and shape of an enzyme. In particular, the role of the amino acid R groups in stabilising the shape should be covered. (P4)
Enzymes are important catalysts for biochemical reactions. Enzymes can speed up the biochemical reactions by providing another reaction pathway of lower activation energy.
Enzymes are generally globular proteins. The protein molecules such as tertiary structure have given the molecule a mostly rounded, ball shape like structure. The globular structure of proteins can be active catalysts. Enzymes are very important and very specific about what they can catalyse. The small changes in the reactant molecule during the reaction can stop the enzyme activity from catalysing the process of reaction.
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The active site is the part of molecules in which the impartial of a right shape and the impartial of right arrangement of the functional groups can fit into these active sites. Some molecules have not right groups to bind to the surface of the active site or they are not fitted. The Reactant in an enzyme during the reaction is known as substrate. A substrate can fits into its enzyme accurately and shape of the substrate can easily form the bond with the enzyme.
Enzymes are protein molecules contain long chains of amino acid remains. Those chains are containing the side groups (R-groups) of the amino acids. In Active sites the "R" groups are present which are lining from about 3 to 12. These R- groups have the variety of features which are responsible for the tertiary structure in proteins. They can contain ionic groups such as -NH3+ or -COO-, or -OH groups which can contain hydrogen bond or hydrocarbon chains which can subsidise to van der Waals forces.
The substrate of molecule can attach to the active site if substrate molecule has a planning of groups in the right places to interact with the enzyme. When a set interactions occur in an active site between two ionic bonds and a hydrogen
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Some non-protein fragments are needed to make them able to do work. These are well known as cofactors. The Cofactors of enzymes may be:
Contain Organic groups which are forever bound with the enzyme e.g. prosthetic group. Other contain cations which have positively charged metal ions or activators which are slightly bind the shape of an active site of the enzyme and giving a strong positive charge to the enzyme.
The organic molecules commonly made from vitamins or coenzymes which are temporarily bound with the enzyme molecule it can also combine temporarily with the enzyme-substrate complex.
If the right cofactor of an enzyme is absence the enzyme is not able to do work which mean that it is inactive protein molecule is well-known as an apoenzyme. When the cofactor of an enzyme is in place which means it develops an active protein molecule it’s known as holoenzyme.
Lock and key hypothesis: this model is show in very simple way that how an enzyme works. When the substrates are fits into the active site of an enzyme it forms a reaction