Question

HELP! WILL GIVE OUT MEDAL TO THE BEST ANSWER. The term 'specific' as applied to enzymes means that each enzyme is specific for a particular reaction. What structural feature of enzymes gives rise to this specificity?

Answer 1

Specificity refers to how the enzyme is going to catalyze a particular reaction; many enzymes are substrate specific and can only catalyze particular reactions whereas others can catalyze a multitude of reactions.

Absolute specificity - the enzyme will catalyze only one reaction.
Group specificity - the enzyme will act only on molecules that have specific functional groups, such as amino, phosphate and methyl groups.
Linkage specificity - the enzyme will act on a particular type of chemical bond regardless of the rest of the molecular structure.
Stereochemical specificity - the enzyme will act on a particular steric or optical isomer.

Answer 2

Specificity refers to shape of active site
lock -and- key complex
how the enzyme will catalyze a reaction only if substrate fits its active site
active site is due to Tertiary or Quaternary 3D structures of enzymes
this structure has different types of bonds in it and it has polypeptide coiled up in different shapes making it compact
so structural feature of specificity is Active site of an enzyme which allows reaction to occur on it as long as reactant/substrate fits the active site of the enzyme

Answer 3

The following has been excerpted from a very popular Worthington publication which was originally published in 1972 as the Manual of Clinical Enzyme Measurements. While some of the presentation may seem somewhat dated, the basic concepts are still helpful for researchers who must use enzymes but who have little background in enzymology.

Specificity of Enzymes
One of the properties of enzymes that makes them so important as diagnostic and research tools is the specificity they exhibit relative to the reactions they catalyze. A few enzymes exhibit absolute specificity; that is, they will catalyze only one particular reaction. Other enzymes will be specific for a particular type of chemical bond or functional group. In general, there are four distinct types of specificity:

Absolute specificity - the enzyme will catalyze only one reaction.
Group specificity - the enzyme will act only on molecules that have specific functional groups, such as amino, phosphate and methyl groups.
Linkage specificity - the enzyme will act on a particular type of chemical bond regardless of the rest of the molecular structure.
Stereochemical specificity - the enzyme will act on a particular steric or optical isomer.
Though enzymes exhibit great degrees of specificity, cofactors may serve many apoenzymes. For example, nicotinamide adenine dinucleotide (NAD) is a coenzyme for a great number of dehydrogenase reactions in which it acts as a hydrogen acceptor. Among them are the alcohol dehydrogenase, malate dehydrogenase and lactate dehydrogenase reactions.