Common properties of enzymes

There are 5 differences or general properties of enzymes:

a) A complicity structure of enzymes

b) The enzymes are compounds which have a high proper of action, or high activity

c) The enzymes have specificity

d) The enzymes act in physiologic conditions, for example in temperature about 37 and neutral pH

e) The enzymes are compounds with regulated activity and different factors act on they activity, t, pH, effectors, concentration of substrates and enzymes.

The complicity of structure of enzymes.

There are one- component enzymes and two – component enzymes

One- component enzymes or simpleare simple proteins, but they differ from simple proteins by the presence of active centre. Active centre is a functional group of amino acids occurred in space. Active centre has got next sites:

- Substrate site – “the hand of enzymes” or contactive site, or anchors place. This site stipulates substrates specificity of enzymes;

- Catalytic site which responsible for chemical reaction.

This site stipulates a specificity of action of enzymes. Some of enzymes have a quaternary structure a do the allosteric centers. The allosteric centre takes part in regulation of activity of enzymes. Almost all of enzymes of gastrointestinal tract are one- component.

Two- componentsenzymes are built as conjugated proteins. They consist of proteins part, or apoenzyme and non- proteins part, or coenzyme. Apoenzymes stipulate a substrates specifyty; coenzyme promotes specificity of action. The composition of coenzyme may be vitamins or metals. Some of two- components enzymes have a durable bond between apo-and coenzyme.

Some two- component enzymes have got an isoforms “isoenzyme”. Isoenzyme act the substrate catalyzed some reactions. Isoenzyme has the some coenzymes, but differs from each other by the structure of apoenzyme. Isoenzyme occurs in a certain tissues.

This property of isoenzyme is named “organo specificity” and pays very important role in diagnosis test.

For example, enzyme lactate dehydrogenase has got 5 (5 isoforms) isoenzyme.

LDG-1- heart

LDG-2- kidneys

LDG-3- lung

LDG-4- liver

LDG-5- liver

In the damage of some organs the LDG exist into the blood and its concentration in blood is increase. In physiologic conditions the level of LDG equal 5 units and relationships between isoenzymes is next LDG_-1,3 : LDG-_4,5 (4.0 : 6,0). In pathological conditions the level of LDG is increased . If the damage of heart or lung the level of LDG-1,3 is increase and the relationships between LDG isoforms is next: LDG_-1,3 : LDG-_4,5

50 : 50

or 60 : 40

If the damage of liver is observed the level of LDG_- is increased and the relation ship between LDG- isoenzymes is next: LDG_-1,3 : LDG-_4,5

30 : 70

20 : 80

The next property of enzymes is high activity. The activity of enzymes is measured in catal. Catal – is a quantity of molecular f substrate on which the molecule enzyme acts during 1 m/n. f.ex: enzymes catalase has got activity 1 m/in catal, if means that the 1 molecule of catalase acts on 1 m/n of its substrate during 1 min.

The next property of enzymes is specificity.There are 2 types of enzymatic specificity

Specificity

Substrate specificity Specificity of action